Solution Combustion Synthesis of Nanoscale Materials

Production of Cu0.5Zn0.5Fe2O4 Nanostructures as a Hyperthermia Agent for Cancer Healing

Cancer is a pervasive and devastating disease affecting various parts of the body, posing significant challenges to human societies. Recently, the development of novel magnetic and biocompatible nanoparticles has emerged as a promising approach for magnetic hyperthermia in cancer treatment, complementing existing therapeutic methods. In the present work, Cu0.5Zn0.5Fe2O4 mixed spinel nanoparticles were produced via a sol-gel combustion route. The produced magnetic nanopowders were studied via FTIR, SEM, XRD, and VSM techniques. XRD results confirmed the formation of the spinel structure of ferrites. Microstructural investigations showed that the synthesized nanoparticles have a particle size ranging from 20 to 200 nm. The VSM results displayed that the saturation magnetization and coercivity of Cu0.5Zn0.5Fe2O4 nanoparticles were 57 emu/g and 24 Oe, respectively. Saturation magnetization for the Cu0.5Zn0.5Fe2O4 specimens improved with increasing heat treatment temperature. In order to examine the samples' heating effectiveness for magnetic hyperthermia therapy, various magnetic fields were used. The temperature of the Cu0.5Zn0.5Fe2O4 powders increased from 37°C to 47°C in 10 min when exposed to a 400-Oe magnetic field and 200-kHz frequency. Results showed that the fabricated products have the potential to be used as hyperthermia agents for cancer therapy. The novelty of this study focuses on the use of Cu0.5Zn0.5Fe2O4 mixed spinel as a new hyperthermia agent with more biocompatible constituent elements.

One-Step Preparation of Trinary Co(III)/Co(II)/Co(0) Bifunctional Catalysts with Controllable Co Valence Distribution via Solution Combustion Synthesis and Its Application to Oxygen Reduction and Evolution in Zinc-Air Batteries

Regulating the electronic structure and chemical valence of the active site for electrocatalysis is highly crucial and challenging. In this work, a cost-effective and facile strategy for regulating the cobalt valence distribution through one-step solution combustion synthesis via cobalt nitrate (oxidizer) and glycine (fuel) was developed to prepare a bifunctional Co(III)/Co(II)/Co(0) catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in a zinc-air battery. Experimental findings show that when increasing the fuel/oxidizer ratio φ, the composition of the synthesized catalyst gradually changes from binary Co(III)/Co(II) to trinary Co(III)/Co(II)/Co(0), and the average Co valence keeps decreasing. As the content of Co(II)/Co(0) increases, the ORR performance of the sample gradually improves. The sample synthesized at φ = 1.2 shows the best bifunctional catalytic activity and was employed to assemble a rechargeable zinc-air battery. Overall, compared with the published data, the proposed catalyst has a comparable ORR/OER activity and catalyst stability, with an excellent battery life, efficiency, and stability (up to 160 h). This work provides a promising pathway for designing the valence state distribution of non-noble cobalt-based catalysts, which can be easily prepared on a large scale with low cost and used in various technologies involved in ORR and OER reactions.

Rapid synthesis of metastable materials for electrocatalysis

Metastable materials are considered promising electrocatalysts for clean energy conversions by virtue of their structural flexibility and tunable electronic properties. However, the exploration and synthesis of metastable electrocatalysts via traditional equilibrium methods face challenges because of the requirements of high energy and precise structural control. In this regard, the rapid synthesis method (RSM), with high energy efficiency and ultra-fast heating/cooling rates, enables the production of metastable materials under non-equilibrium conditions. However, the relationship between RSM and the properties of metastable electrocatalysts remains largely unexplored. In this review, we systematically examine the unique benefits of various RSM techniques and the mechanisms governing the formation of metastable materials. Based on these insights, we establish a framework, linking RSM with the electrocatalytic performance of metastable materials. Finally, we outline the future directions of this emerging field and highlight the importance of high-throughput approaches for the autonomous screening and synthesis of optimal electrocatalysts. This review aims to provide an in-depth understanding of metastable electrocatalysts, opening up new avenues for both fundamental research and practical applications in electrocatalysis.

Confined Growth by Self-Combustion of a Cu-Based Nanophase into Mesostructured Acid Supports for DME Production from CO2

This work deals with the design of nanocomposite hydrogenation-dehydration bifunctional catalysts for the one-pot conversion of CO2 to dimethyl ether (DME), focusing on obtaining a high and homogeneous dispersion of a Cu-based CO2 hydrogenation phase into the pores of mesostructured supports. Particularly, three aluminosilicate mesostructured acid catalysts with catalytic activity towards methanol dehydration and featuring different porous structures (Al-MCM-41, Al-SBA-15, Al-SBA-16) were synthesized and used as supports to host a CuO/ZnO/ZrO2 (CZZ) CO2 hydrogenation catalyst for methanol synthesis. The use of a mesostructured support allows to maximize the exposed surface of the CO2 reduction function by nanostructuring it through its confinement within the mesochannels, thus obtaining nanocomposite bifunctional catalysts with an ultra-small hydrogenation nanophase. The nanocomposites were obtained using an impregnation strategy combined with a self-combustion reaction, allowing to incorporate the CO2 reduction phase inside the mesopores. In all cases, the characterization shows that the hydrogenation phase species are highly and homogeneously dispersed into the supports as either small nanoparticles or as a nanolayer. The as-obtained nanocomposites were tested for their catalytic activity and the results discussed taking into account the structural, textural, and acidic properties of the supports and nanocomposites.

Exploration of the Reduction Diffusion Temperature for Different Phases of Samarium-Cobalt Magnetic Particles

We report a method for synthesizing different phases of samarium-cobalt particles through microwave-assisted combustion combined with high-temperature reduction and diffusion, and identify the optimal temperature for forming the 1:5 phase using this approach. Initially, the samarium-to-cobalt ratio in a nitrate solution was determined. Using urea as both a reductant and fuel, samarium-cobalt oxides were synthesized via microwave-assisted combustion. The main components of the oxides were confirmed to be SmCoO3 and Co3O4. Subsequently, samarium-cobalt particles were synthesized at various diffusion temperatures. The results indicate that at 700 °C, the oxides were reduced to elemental Sm and Co. As the reduction temperature increased, the alloying of samarium and cobalt occurred, and the particle size gradually increased. At 900 °C, a pure 1:5 phase was formed, with particle sizes of approximately 800 nm, a coercivity of 35 kOe, and a maximum energy product of 14 MGOe. Based on the microwave-assisted combustion method, this study clarifies the transition temperatures of samarium-cobalt phases during the reduction and diffusion process, and further establishes the synthesis temperature for the 1:5 phase, providing new insights into the preparation and development of samarium-cobalt materials and potentially other rare earth materials.

Structural control over single-crystalline oxides for heterogeneous catalysis

Oxides are integral to heterogeneous catalysis, serving critical roles such as catalyst supports, active materials and electrodes. A highly ordered subset, single-crystalline oxides, have traditionally been used as model catalyst supports in fundamental surface science studies. However, advancements in bulk synthesis have rendered their general use more feasible for real-world applications. In this review, we explore the efficiency of single-crystalline oxides as active metals and supports across a wide range of heterogeneous processes, often performing exceptionally well. Beginning with synthetic methods, we discuss the advantages of single-crystalline oxides in thermo-, electro- and photocatalysis. Previously held conventions about catalytic activity, deactivation and surface-adsorbate interactions are re-evaluated by understanding how these ordered materials behave during the respective reactions. Last, we assess advances in characterization techniques and their impact on designing the next generation of catalysts based on single-crystalline oxides.

Facile synthesis, characterisation and application of zinc ferrite in removal of uranium from water by adsorption

The present study features about the adsorption efficacy of Zinc ferrite (ZnFe₂O₄) in removing uranium from both synthetic and real groundwater samples. ZnFe₂O₄ was synthesized via the Solution Combustion Method and subsequently characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and spectroscopic techniques, including Fourier transform Infrared (FTIR) spectroscopy and Raman spectroscopy, to assess its structural properties. The textural characteristics of the synthesized material were examined through N₂ adsorption-desorption isotherm analysis. Furthermore, X-ray photoelectron spectroscopy (XPS) and Electron spin resonance (ESR) spectroscopy were used to check and investigate the electronic states and magnetic properties of ZnFe₂O₄, respectively. Parametric batch adsorption experiments were conducted at ambient conditions by varying the uranyl (U(VI)) concentration (10-50 ppm), contact time (0-90 min), adsorbent dosage (0.1-1 g), and solution pH (3-10). The ZnFe₂O₄ nanoparticles exhibited >90 % of U (VI) adsorption at a contact time of 60 min, at pH 6, and an adsorbent dosage of 0.3 g for a 10-ppm U(VI) solution. The adsorption process was best described by the Langmuir model, with a maximum adsorption capacity of 5 mgg-1. Additionally, kinetic studies revealed a pseudo-second-order kinetic model with an equilibrium adsorption capacity of 28.68 mgg-1. The application of 0.3 g of ZnFe₂O₄ was also found to facilitate approximately 90 % U(VI) removal from groundwater samples. The ZnFe₂O₄ nanoparticles demonstrated notable adsorption efficiency and regeneration capability, sustaining performance over five consecutive adsorption-desorption cycles. These findings suggest that ZnFe₂O₄ has potential for remediation of U(VI)-contaminated water under ambient conditions.

Recent Advances on the Gas-Sensing Properties and Mechanism of Perovskite Oxide Materials - A Review

Perovskite oxide-based materials (ABO3) have gained much attention as promising candidates for advanced gas-sensing applications due to their versatile structures, tunable properties, and excellent stability. This review discusses recent developments in the synthesis, structural optimization, and functionalization of perovskites to enhance their gas-sensing performance. Strategies such as doping, creating oxygen vacancies, tuning morphology, and forming heterojunctions have significantly improved their sensitivity, selectivity, response, and recovery times. Specific advances include the incorporation of nanostructures, porous morphologies, and catalytic elements, which have optimized the adsorption and desorption processes for various target gases, including volatile organic compounds, NO2, and CO2. Mechanistic insights into the role of oxygen vacancies, surface defects, and charge carrier dynamics are also addressed. These developments position perovskite materials as important components in next-generation gas sensors for environmental monitoring and industrial applications.

Exploring the electrical and magnetic characteristics of novel barium-doped bismuth ferrite (Bi0.9Ba0.1FeO3) nanocomposites and their applications for electrocatalytic degradation of Congo red dye

Bismuth perovskite Bi0.9Ba0.1FeO3 nanoparticles were synthesized by a solution-combustion technique at a fuel-to-oxidizer ratio equal to unity (∅ = (F/O) = 1), where the effect of fuel type on their structural, electric, magnetic, and photocatalytic properties was discussed. Using Rietveld refinement with FullProf software, the prepared materials were characterized by XRD and SEM to examine their composition and morphology. Results revealed that the perovskite's pure phase ranged from 74% to 100%. Meanwhile, Scherrer, Williamson-Hall, and SEM investigations were used to calculate the crystallite sizes of the samples, which ranged from 18.5-27.7 nm, 23-32 nm, 23.8-34.3 nm, and 53.8-292.8 nm, respectively. In addition, the increase in DC conductivity is explained by decreased grain boundary scattering, due to the reduction of crystallite size. The multiferroic nanoparticles' estimated activation energy ranged from 0.39 to 0.07 eV. The transition temperature was 368 K for urea and triethanolamine (TEA) samples, while the other samples were pushed to a lower temperature, where conduction followed non-adiabatic small polaron hopping (SPH). Meanwhile, TEA and fuel-free samples appear to have a high magnetization parameter. The coercivity Hc of the TEA sample is three times greater than the others. According to the tests conducted to assess the nanoparticles' electrocatalytic performances, every fuel utilized in nanoparticle production process significantly impacts the electrocatalytic degradation of Congo red (CR) dye. When the 4 minutes experiment was over, all dye content in the solution was eliminated. The synthesized Bi0.9Ba0.1FeO3 using various fuels considerably impacts the parameters under study. Therefore, appropriate magnetic, electrical, and electrocatalysis properties were achieved by modifying the fuel type.

Perovskite Type ABO3 Oxides in Photocatalysis, Electrocatalysis, and Solid Oxide Fuel Cells: State of the Art and Future Prospects

Since photocatalytic and electrocatalytic technologies are crucial for tackling the energy and environmental challenges, significant efforts have been put into exploring advanced catalysts. Among them, perovskite type ABO3 oxides show great promising catalytic activities because of their flexible physical and chemical properties. In this review, the fundamentals and recent progress in the synthesis of perovskite type ABO3 oxides are considered. We describe the mechanisms for electrocatalytic oxygen evolution reactions (OER), oxygen reduction reactions (ORR), hydrogen evolution reactions (HER), nitrogen reduction reactions (NRR), carbon dioxide reduction reactions (CO2RR), and metal-air batteries in details. Furthermore, the photocatalytic water splitting, CO2 conversion, pollutant degradation, and nitrogen fixation are reviewed as well. We also stress the applications of perovskite type ABO3 oxides in solid oxide fuel cells (SOFs). Finally, the optimization of perovskite type ABO3 oxides for applications in various fields and an outlook on the current and future challenges are depicted. The aim of this review is to present a broad overview of the recent advancements in the development of perovskite type ABO3 oxides-based catalysts and their applications in energy conversion and environmental remediation, as well as to present a roadmap for future development in these hot research areas.

Ni1-x Mn x Co2O4 Nanoparticles as High-Performance Electrochemical Sensor Materials for Acetaminophen Monitoring

Ternary metal oxides, known for their superior electrical and optical properties compared to binary or conventional oxides, hold significant promise for catalysis and energy storage applications. This study investigates the electrochemical performance of Ni1-x Mn x Co2O4 nanoparticles for detecting acetaminophen in aqueous phosphate buffer solution. The cobaltite nanoparticles were obtained through a simple gel-combustion synthesis, and the sensors were characterized using cyclic voltammetry, chronoamperometry, and differential pulse voltammetry. The anodic peak currents associated with acetaminophen oxidation were assessed by varying the scan rate of current-voltage cycles. Among the sensors tested, the one fabricated with Ni0.5Mn0.5Co2O4 nanoparticles as an active material exhibited the highest sensitivity of 38.2 μA cm-2 mM-1 and a detection limit of approximately 2 μM, demonstrating its potential for sensitive and efficient acetaminophen detection. Moreover, the sensors fabricated using these ternary oxide nanostructures demonstrate a rapid chronoamperometric response time of 35.4 s and a decay lifetime of 0.31 s, highlighting the fast detection capabilities of acetaminophen. The electrochemical oxidation mechanism of acetaminophen and the charge transfer characteristics at the electrode-electrolyte interface have been discussed.

High-Entropy Engineering for Multivalency-Induced Stability in SnSb-Based Anodes

Achieving high energy density and long cycle life in alloy-type anodes remains a significant challenge due to the large volume changes during cycling. Here, we introduce a high-entropy engineering approach using SnSb-based oxides codoped with Ti and Al (SSBTA-600), designed to promote the formation of efficient oxygen vacancies at a calcination temperature of 600 °C. This approach results in remarkable performance with a capacity of 1012 mAh g-1 at 0.5 A g-1 and 297 mAh g-1 at 5 A g-1 after 500 cycles, with superior capacity retention of 99% and 83.5%, respectively. A LiFePO4||SSBTA full cell achieves 134 mAh g-1 after 100 cycles with 89.4% retention, demonstrating its practical potential for lithium-ion batteries. The high concentration of oxygen vacancies in SSBTA-600, induced by the multivalency of Ti and Al, is validated by electron paramagnetic resonance (EPR) and X-ray absorption spectroscopy (XAS). This high-entropy engineering approach significantly improves the cyclic stability and high-rate performance and provides a promising strategy for enhancing the energy density and cycle life in alloy-type anodes.

CO Oxidation Catalyzed by Perovskites: The Role of Crystallographic Distortions Highlighted by Systematic Experiments and Artificial Intelligence

The identification of key materials' parameters correlated with the performance can accelerate the development of heterogeneous catalysts and unveil the relevant underlying physical processes. However, the analysis of correlations is often hindered by inconsistent data. Besides, nontrivial, yet unknown relationships may be important, and the intricacy of the various processes may be significant. Here, we tackle these challenges for the CO oxidation catalyzed by perovskites using a combination of rigorous experiments and artificial intelligence. A series of 13 ABO3 (A=La, Pr, Nd, Sm; B=Cr, Mn, Fe, Co) perovskites was synthesized, characterized, and tested in catalysis. To the resulting dataset, we applied the symbolic-regression SISSO approach. We identified an analytical expression correlated with the activity that contains the normalized unit-cell volume, the Pauling electronegativity of the elements A and B, and the ionization energy of the element B. Therefore, the activity is described by crystallographic distortions and by the chemical nature of A and B elements. The generalizability of the identified descriptor is confirmed by the good quality of the predictions for 3 additional ABO3 and 16 chemically more complex AMn(1-x)B'xO3 (A=La, Pr, Nd; B'=Fe, Co, Ni, Cu, Zn) perovskites.

Solvent Selection as a Key Factor in the Performance of Semitransparent Heterojunctions Composed of Hydrogenated Nanotubes and Bismuth Sulfides

Research on titanium nanotubes modified with metal sulfides, particularly bismuth sulfide (Bi2S3), aims to create heterostructures that efficiently absorb sunlight and then separate photogenerated charge carriers, thereby enhancing the energy conversion efficiency. This study shows a key role of solvent used for sulfide and bismuth salt solutions used during successive ionic layer adsorption and reaction (SILAR) onto the morphology, structure, and photoresponse of the heterojunction where one element is represented by semitransparent titania nanotubes (gTiNT) and the second is Bi2S3. Using 2-methoxyethanol and methanol during SILAR, results in remarkably photoactive 3D heterostructure and recorded photocurrents were 44 times higher compared to bare titania nanotubes. Additionally, methanol- and 2-methoxyethanol-based processing allowed uniform deposition of the sulfide, which was not reached for other solvents. XPS studies not only confirm formation of bismuth sulfides but also indicate that BixTiyOz compound can arise that can affect both stability and photoactivity of the electrode material.

A Review of Nanomaterials and Microwave Synthesized Metal Oxides Nanoparticles in Schistosomiasis Diagnosis

Point of Care (POC) diagnosis provides an effective approach for controlling and managing Neglected Tropical Diseases (NTDs). Electrochemical biosensors are well-suited for molecular diagnostics due to their high sensitivity, cost-effectiveness, and ease of integration into POC devices. Schistosomiasis is a prominent NTD highly prevalent in Africa, Asia, and Latin America, with significant socioeconomic implications such as discrimination, reduced work capacity, or mortality, perpetuating the cycle of poverty in affected regions worldwide. This review explores recent advancements in nanoparticle-based electrochemical biosensors for disease diagnosis, specifically focusing on the schistosome parasite. The synthesis processes and advantages of microwave-assisted preparation of metal oxide nanoparticles are highlighted, showcasing improved purity and energy efficiency compared to traditional combustion methods. In detection prototypes, Schistosome Egg Antigen (SEA) derived from Schistosome mansoni eggs obtained from primary and secondary hosts were evaluated using direct Enzyme-Linked Immunosorbent Assay (ELISA) to measure antibody concentrations in the primary and secondary hosts post-injection. Biosensor system was then developed by modifying developed electrodes with Gold Nanopartcicles (AuNP), Aluminium Gallium Nitride/Gallium Nitride (AlGaN/GaN), Mercaptopropyltrimethoxysilane/Gold Nanoparticles (MPTS/AuNPs) or metal oxide nanoparticles in conjugation with schistosome antibodies, registering current response on interactions with SEA, via cyclic voltammetry (CV), differential pulse voltammetry (DPV), Electrochemical Impedance Spectroscopy (EIS), Amperometry (A) and other electrochemical techniques. This review provides a summary of various constructions of electrochemical biosensors for detecting schistosomiasis.

Platelet Ceria Catalysts from Solution Combustion and Effect of Iron Doping for Synthesis of Dimethyl Carbonate from CO2

Solution combustion (SC) remains among the most promising synthetic strategies for the production of crystalline nanopowders from an aqueous medium, due to its easiness, time and cost-effectiveness, scalability and eco-friendliness. In this work, this method was selected to obtain anisometric ceria-based nanoparticles applied as catalysts for the direct synthesis of dimethyl carbonate. The catalytic performances were studied for the ceria and Fe-doped ceria from SC (CeO2-SC, Ce0.9Fe0.1O2-SC) in comparison with the ceria nanorods (CeO2-HT, Ce0.9Fe0.1O2-HT) obtained by hydrothermal (HT) method, one of the most studied systems in the literature. Indeed, the ceria nanoparticles obtained by SC were found to be highly crystalline, platelet-shaped, arranged in a mosaic-like assembly and with smaller crystallite size (≈6 nm vs. ≈17 nm) and higher surface area (80 m2 g-1 vs. 26 m2 g-1) for the undoped sample with respect to the Fe-doped counterpart. Although all samples exhibit an anisometric morphology that should favor the exposition of specific crystalline planes, HT-samples showed better performances due to higher oxygen vacancies concentration and lower amount of strong basic and acid sites.

Dynamically Reconstructed Fe-CoOOH Semi-Crystalline Electrocatalyst for Efficient Oxygen Evolution Reaction

The development of robust and efficient electrocatalysts for the oxygen evolution reaction (OER) has been the main focus of water electrolysis but remains a great challenge. Here, the synthesis of a highly active and ultra-stable Fe-CoOOH electrocatalyst is reported by steering raw cobalt foam via an in situ solution combustion method assisted by a galvanic replacement reaction and subsequent electrochemical reconstruction of the CoFeOx pre-catalyst. In/ex situ electrochemical analysis and physicochemical characterizations show that the CoFeOx undergoes quick chemical and slow morphological reconstruction to Fe-CoOOH nanosheets. The Fe-CoOOH possesses a semi-crystalline nature with distinct short-range ordering and outstanding OER activity with overpotentials as low as 271 and 291 mV at current densities of 500 and 1,000 mA cm-2, respectively. The remarkable stability under 1,000 mA cm-2 for at least 700 h is achieved. Theoretical calculations confirm the crucial role of Fe doping in facilitating surface reconstruction, enhancing OER activity, and improving the stability of the Fe-CoOOH. Comparative analysis with other transition metals doping reveals the unique ability of Fe to adsorb onto the CoOOH surface, thereby modulating the electronic density and facilitating faster adsorption of reaction intermediates. This work represents valuable insights into the surface reconstruction and doping processes.

Role of Nanoformulations in the Treatment of Lung Cancer

Lung cancer is the second deadliest disease in the world. A major portion of deaths related to cancer are due to lung cancer in both males and females. Interestingly, unbelievable advances have occurred in recent years through the use of nanotechnology and development in both the diagnosis and treatment of lung cancer. Due to their in vivo stability, the nanotechnology-based pharmacological system gained huge attractiveness, solubility, absorption from the intestine, pharmacological effectiveness, etc. of various anticancer agents. However, this field needs to be utilized more to get maximum results in the treatment of lung cancer, along with wider context medicines. In the present review, authors have tried to concentrate their attention on lung cancer`s difficulties along with the current pharmacological and diagnostic situation, and current advancements in approaches based on nanotechnology for the treatment and diagnosis of lung cancer. While nanotechnology offers these promising avenues for lung cancer diagnosis and treatment, it is important to acknowledge the need for careful evaluation of safety, efficacy, and regulatory approval. With continued research and development, nanotechnology holds tremendous potential to revolutionize the management of lung cancer and improve patient outcomes. The review also highlights the involvement of endocrine systems, especially estrogen in lung cancer proliferation. Some of the recent clinical trials and patents on nanoparticle-based formulations that have applications in the treatment and diagnosis of lung cancer are also discussed.

Bimetallic CuNi Nanoparticle Formation: Solution Combustion Synthesis and Molecular Dynamic Approaches

Nanomaterials are vital in catalysis, sensing, energy storage, and biomedicine and now incorporate multiprincipal element materials to meet evolving technological demands. However, achieving a uniform distribution of multiple elements in these nanomaterials poses significant challenges. In this study, various Cu-Ni compositions were used as a model system to investigate the formation of bimetallic nanoparticles by employing computer simulation molecular dynamics methods and comparing the results with observations from solution-combustion-synthesized materials of the same compositions. The findings reveal the successful synthesis of 12-18 nm bimetallic Cu-Ni nanoparticles with high phase homogeneity, alongside phase-segregated nanoparticles predicted by molecular dynamics simulations. Based on the comparison of the experimental and computational data, a possible scenario for phase segregation during the synthesis was proposed. It includes clustering of the atoms of the same type in an initial solution or the stage of gel formation and further developing segregation during the combustion/cooling stage. The research concludes that early synthesis stages, including particle preformation, significantly influence the phase homogeneity of multiprincipal element alloys. This study contributes to understanding nanomaterial formation, offering insights for improved alloy synthesis and enhanced functionalities in advanced applications.

The catalytic effect of chromium-doped ceria-praseodymium on soot oxidation activity and its kinetics

Soot generated from the partial combustion of diesel significantly contributes to air pollution, and catalytic oxidation is currently an effective method for removing diesel soot particles. The chromium-doped ceria-praseodymium (Cr-CP) catalyst system is synthesized via solution combustion synthesis and evaluated for soot oxidation activity, with a subsequent kinetics study conducted. The XRD analysis of the catalysts indicated a decrease in crystallite size and increased lattice strain and reactive facet ratios for all Cr-doped CP samples. Raman analysis verified the existence of oxygen vacancy peaks in all chromium-doped CP catalysts. X-ray photoelectron spectroscopy (XPS) revealed the presence of adsorbed H2O or molecular water peaks in the O1s spectra for the 5 Cr-CP catalyst, which also exhibited a high concentration of surface Cr3+ ions. Thermogravimetric analysis (TGA) of soot oxidation indicated that 5 Cr-CP exhibited a superior T50 of 393 ± 2 °C, mostly attributed to the presence of reducible surface Cr3+ ion species. Kinetic analysis was performed on all Cr-doped CP catalysts to assess the kinetic triplets: activation energy, pre-exponential factor, and reaction model. The activation energy was low (87 kJ mol-1, Ozawa method) for 15 Cr-CP, while the pre-exponential factor was higher for 5 Cr-CP (7.39 × 1010 min-1). The Cr-CP catalyst system adhered to a power law, indicating a phase boundary-controlled reaction characterized by nucleation and growth mechanisms. The consistency between experimental and calculated curves confirmed that the developed catalysts adhered to the Avrami-Erofeev equation (Am) or the nucleation and growth model.

Advances in Functional Organosulfur-Based Mediators for Regulating Performance of Lithium Metal Batteries

Rechargeable lithium metal batteries (LMBs) are promising next-generation energy storage systems due to their high theoretical energy density. However, their practical applications are hindered by lithium dendrite growth and various intricate issues associated with the cathodes. These challenges can be mitigated by using organosulfur-based mediators (OSMs), which offer the advantages of abundance, tailorable structures, and unique functional adaptability. These features enable the rational design of targeted functionalities, enhance the interfacial stability of the lithium anode and cathode, and accelerate the redox kinetics of electrodes via alternative reaction pathways, thereby effectively improving the performance of LMBs. Unlike the extensively explored field of organosulfur cathode materials, OSMs have garnered little attention. This review systematically summarizes recent advancements in OSMs for various LMB systems, including lithium-sulfur, lithium-selenium, lithium-oxygen, lithium-intercalation cathode batteries, and other LMB systems. It briefly elucidates the operating principles of these LMB systems, the regulatory mechanisms of the corresponding OSMs, and the fundamentals of OSMs activity. Ultimately, strategic optimizations are proposed for designing novel OSMs, advanced mechanism investigation, expanded applications, and the development of safe battery systems, thereby providing directions to narrow the gap between rational modulation of organosulfur compounds and their practical implementation in batteries.

Synthesis and catalytic application of nanostructured metal oxides and phosphates

The design and development of new high-performance catalysts is one of the most important and challenging issues to achieve sustainable chemical and energy production. This Feature Article describes the synthesis of nanostructured metal oxides and phosphates mainly based on earth-abundant metals and their thermocatalytic application to selective oxidation and acid-base reactions. A simple and versatile methodology for the control of nanostructures based on crystalline complex oxides and phosphates with diverse structures and compositions is proposed as another approach to catalyst design. Herein, two unique and verstile methods for the synthesis of metal oxide and phosphate nanostructures are introduced; an amino acid-aided method for metal oxides and phosphates and a precursor crystallization method for porous manganese oxides. Nanomaterials based on perovskite oxides, manganese oxides, and metal phosphates can function as effective heterogeneous catalysts for selective aerobic oxidation, biomass conversion, direct methane conversion, one-pot synthesis, acid-base reactions, and water electrolysis. Furthermore, the structure-activity relationship is clarified based on experimental and computational approaches, and the influence of oxygen vacancy formation, concerted activation of molecules, and the redox/acid-base properties of the outermost surface are discussed. The proposed methodology for nanostructure control would be useful not only for the design and understanding of the complexity of metal oxide catalysts, but also for the development of innovative catalysts.

Biophysical translational posterity of green carbon quantum dots: the unparalleled versatility

Carbon dots (CQDs), zero-dimensional carbon nanostructures, have attracted considerable interest among researchers due to their versatile applications. CQDs exhibit exceptional photoluminescent properties and high quantum yield, making them ideal candidates for bioimaging, drug delivery and environmental sensing. Their biocompatibility and tunable surface chemistry enable targeted therapeutic delivery and real-time imaging with minimal toxicity. Additionally, CQDs are emerging as promising materials in optoelectronics, offering sustainable alternatives in light-emitting diodes and solar cells. This review underscores the unparalleled adaptability of green CQDs in bridging the gap between laboratory research and practical applications, paving the way for innovative solutions in healthcare and environmental monitoring. Through comprehensive analysis, it advances the understanding of CQDs, positioning them at the forefront of next-generation nanomaterials with significant translational impact.

Ordered versus Non-Ordered Mesoporous CeO2-Based Systems for the Direct Synthesis of Dimethyl Carbonate from CO2

In this work, non-ordered and ordered CeO2-based catalysts are proposed for CO2 conversion to dimethyl carbonate (DMC). Particularly, non-ordered mesoporous CeO2, consisting of small nanoparticles of about 8 nm, is compared with two highly porous (635-722 m2/g) ordered CeO2@SBA-15 nanocomposites obtained by two different impregnation strategies (a two-solvent impregnation method (TS) and a self-combustion (SC) method), with a final CeO2 loading of 10 wt%. Rietveld analyses on XRD data combined with TEM imaging evidence the influence of the impregnation strategy on the dispersion of the active phase as follows: nanoparticles of 8 nm for the TS composite vs. 3 nm for the SC composite. The catalytic results show comparable activities for the mesoporous ceria and the CeO2@SBA-15_SC nanocomposite, while a lower DMC yield is found for the CeO2@SBA-15_TS nanocomposite. This finding can presumably be ascribed to a partial obstruction of the pores by the CeO2 nanoparticles in the case of the TS composite, leading to a reduced accessibility of the active phase. On the other hand, in the case of the SC composite, where the CeO2 particle size is much lower than the pore size, there is an improved accessibility of the active phase to the molecules of the reactants.

Exploring the diverse applications of sol-gel synthesized CaO:MgAl2O4 nanocomposite: morphological, photocatalytic, and electrochemical perspectives

A nanocomposite of CaO:MgAl2O4 was synthesized through a straightforward and cost-effective sol-gel method. The investigation of the novel CaO:MgAl2O4 nanocomposite encompassed an examination of its morphological and structural alterations, as well as an exploration of its photocatalytic activities and electrochemical characteristics. XRD analysis revealed a nanocomposite size of 24.15 nm. The band gap, determined through UV studies, was found to be 3.83 eV, and scanning electron microscopy (SEM) illustrated flake-like morphological changes in the CaO:MgAl2O4 samples. TEM, HRTEM, and SAED studies of a CaO:MgAl2O4 nanocomposite would reveal important details about its morphology, crystallography, and nanostructure. Photocatalytic activity was quantified by studying the degradation of Acid Red-88 (AR-88) dye in a deionized solution, achieving a 70% dye degradation under UV irradiation in 120 min. Plant growth examinations were carried out using dye degraded water to test its suitability for agriculture. The electrochemical energy storage and sensing applications of the prepared nanocomposite were examined using CaO:MgAl2O4 modified carbon paste electrode through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In conclusion, the synthesized CaO:MgAl2O4 nanocomposite demonstrated promising morphological and structural characteristics, efficient photocatalytic activity, and potential applications in electrochemical energy storage, highlighting its versatility for various technological and environmental applications.

Structural and Luminescent Properties of Dy(III) Doped Ca0.5Bi3P2O10 Nanophosphors for Solid-State Lighting & Latent Fingerprinting Applications

An efficient urea-assisted SC (solution-combustion) approach was used to synthesize a novel series of doped Ca0.5Bi3P2O10: xDy3+ nanophosphors (0.01-0.1 mol). The powdered materials were thoroughly investigated using structural and optical measures. 'Rietveld refinement' investigations found that the produced nanophosphor formed a triclinic system with the P -1 triclinic space group. An EDS (energy-dispersive spectral) study was conducted to determine the corresponding proportions of constituent elements of doped nanophosphors. The TEM (transmission electron microscopy) revealed aggregated particles with a standard size on the nanoscale. The PLE (Photoluminescence excitation) spectrum indicates that the indicated phosphors can be stimulated by NUV (near ultraviolet) illumination sources. The Dy3+-ions undergo transitions from (4F9/2 → 6H15/2 & 4F9/2 → 6H13/2) were recognized as (PL) spectra with an excitation of 353 nm revealed the presence of blue-yellow bands at 481, and 577 nm, correspondingly. Further, PL data was used to determine photometric metrics such as CCT (correlated color-temperature), CC (chromaticity-coordinates (x & y)), and CP (color-purity (%)), supporting their use in solid-state lighting and latent fingerprinting applications.

Unraveling the Role of Particle Size and Nanostructuring on the Oxygen Evolution Activity of Fe-Doped NiO

Nickel-based oxides and oxyhydroxide catalysts exhibit state-of-the-art activity for the sluggish oxygen evolution reaction (OER) under alkaline conditions. A widely employed strategy to increase the gravimetric activity of the catalyst is to increase the active surface area via nanostructuring or decrease the particle size. However, the fundamental understanding about how tuning these parameters influences the density of oxidized species and their reaction kinetics remains unclear. Here, we use solution combustion synthesis, a low-cost and scalable approach, to synthesize a series of Fe0.1Ni0.9O samples from different precursor salts. Based on the precursor salt, the nanoparticle size can be changed significantly from ∼2.5 to ∼37 nm. The OER activity at pH 13 trends inversely with the particle size. Using operando time-resolved optical spectroscopy, we quantify the density of oxidized species as a function of potential and demonstrate that the OER kinetics exhibits a second-order dependence on the density of these species, suggesting that the OER mechanism relies on O-O coupling between neighboring oxidized species. With the decreasing particle size, the density of species accumulated is found to increase, and their intrinsic reactivity for the OER is found to decrease, attributed to the stronger binding of *O species (i.e., a cathodic shift of species energetics). This signifies that the high apparent OER activity per geometric area of the smaller nanoparticles is driven by their ability to accumulate a larger density of oxidized species. This study not only experimentally disentangles the influence of the density of oxidized species and intrinsic kinetics on the overall rate of the OER but also highlights the importance of tuning these parameters independently to develop more active OER catalysts.

Catalytic reduction of toxic dyes over nickel oxide nanoparticles supported on CMK-3 catalyst

In the current paper, a NiO nanoparticles-loaded mesoporous carbon (CMK-3) catalyst, denoted as NiO/CMK-3, has been successfully synthesized using a facile strategy. The as-prepared material has been characterized through XRD, Raman spectroscopy, low-temperature N2 physisorption measurements, FTIR, FE-SEM, TEM, and XPS. The as-fabricated NiO/CMK-3 catalyst manifested a superior activity in the NaBH4-assisted reduction of methylene blue (MB) dye to its colorless leuco form. Remarkably, over 99% of 25 mg L-1 MB was reduced by 7.5 mM/L NaBH4 using 0.1 g L-1 NiO/CMK-3 within 3 min at room temperature. Furthermore, the kinetics study confirmed the appropriateness of the pseudo-first-order kinetic model for elucidating the kinetics of MB reduction by the catalyst. Importantly, the NiO/CMK-3 catalyst maintained almost constant catalytic activity even after 5 times of reuse in MB reduction, demonstrating its superior stability and reusable ability. So, NiO/CMK-5 appears as a promising heterogeneous catalyst for the effective remediation of dye-containing wastewater.

Carbon dots as versatile nanomaterials in sensing and imaging: Efficiency and beyond

Carbon dots (CDs) have emerged as a versatile and promising carbon-based nanomaterial with exceptional optical properties, including tunable emission wavelengths, high quantum yield, and photostability. CDs are appropriate for various applications with many benefits, such as biocompatibility, low toxicity, and simplicity of surface modification. Thanks to their tunable optical properties and great sensitivity, CDs have been used in sensing as fluorescent probes for detecting pH, heavy metal ions, and other analytes. In addition, CDs have demonstrated potential as luminescence converters for white organic light-emitting diodes and light emitters in optoelectronic devices due to their superior optical qualities and exciton-independent emission. CDs have been used for drug administration and bioimaging in the biomedical field due to their biocompatibility, low cytotoxicity, and ease of functionalization. Additionally, due to their stability, efficient charge separation, and low recombination rate, CDs have shown interesting uses in energy systems, such as photocatalysis and energy conversion. This article highlights the growing possibilities and potential of CDs as adaptable nanomaterials in a variety of interdisciplinary areas related to sensing and imaging, at the same time addressing the major challenges involved in the current research and proposing scientific solutions to apply CDs in the development of a super smart society.

Combustion Growth of NiFe Layered Double Hydroxide for Efficient and Durable Oxygen Evolution Reaction

NiFe layered double hydroxide (LDH) with abundant heterostructures represents a state-of-the-art electrocatalyst for the alkaline oxygen evolution reaction (OER). Herein, NiFe LDH/Fe2O3 nanosheet arrays have been fabricated by facile combustion of corrosion-engineered NiFe foam (NFF). The in situ grown, self-supported electrocatalyst exhibited a low overpotential of 248 mV for the OER at 50 mA cm-2, a small Tafel slope of 31 mV dec-1, and excellent durability over 100 h under the industrial benchmarking 500 mA cm-2 current density. A balanced Ni and Fe composition under optimal corrosion and combustion contributed to the desirable electrochemical properties. Comprehensive ex-situ analyses and operando characterizations including Fourier-transformed alternating current voltammetry (FTACV) and in situ Raman demonstrate the beneficial role of modulated interfacial electron transfer, dynamic atomic structural transformation to NiOOH, and the high-valence active metal sites. This study provides a low-cost and easy-to-expand way to synthesize efficient and durable electrocatalysts.

The impact of urban rain on the changes of bare and artificially patinated bronze during 9-year exposure

Atmospheric pollutants in the air form acid rain which interacts with bronze surfaces exposed in urban outdoor environment. In this study, different types of patinas on bronze were investigated during and after 9 years of exposure to urban environment in moderately polluted continental city. Natural bronze patina and artificial brown sulphide, green chloride, and green-blue nitrate patinas were investigated. Visual assessment was carried out at defined periods. After 9 years of exposure, an electrochemical study was performed to investigate the electrochemical activity of the patinas in artificial urban rain. Additionally, the patinas were characterised using a variety of techniques, including metallographic examination, scanning electron microscopy/energy dispersive X-ray spectroscopy, Raman spectroscopy, X-ray diffraction analysis, X-ray-photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry to analyse the surface morphology, chemical composition, and stratigraphic features of the patinas. Evolution of the patinas was shown to be a result of both, the composition of the acid rain and the hydrophobicity of the patinated surfaces.

Smallest unit of maximal entropy as novel experimental criterion for parametric characterization of middle- and high-entropy materials

Materials with multiple principal elements (middle- and high-entropy materials), are used in emerging applications in various fields due to their unique properties, driven by configuration entropy. Improved understanding and experimental investigations of the impact of the entropy of mixing on the properties of these materials are of large practical interest. Here we show a simplified limited area calculation approach for assessing the entropy of mixing using a CoCuFeNi model nanoalloy. Based on our calculations we propose a new parametric entropy-based criterion, which defines critical scale parameter transition from the maximal entropy state to the entropy-depleted state of the system. The criterion could be used for generalized mechanistic assessment of the effect of the entropy of mixing on the characteristics of the materials with multiple principal elements and for the development and characterization of existing and new middle- and high-entropy materials with both simple single-, and more complex, multiple-sublattice structures.

Synthesis of pure and doped nano-calcium phosphates using different conventional methods for biomedical applications: a review

The applications of calcium phosphates (hydroxyapatite, tetracalcium phosphate, tricalcium phosphate (alpha and beta), fluorapatite, di-calcium phosphate anhydrous, and amorphous calcium-phosphate) are increasing day by day. Calcium hydroxyapatite, commonly known as hydroxyapatite (HAp), represents a mineral form of calcium apatite. Owing to its close molecular resemblance to the mineral constituents of bones, teeth, and hard tissues, HAp is often employed in the biomedical domain. In addition, it is extensively employed in various sectors such as the remediation of water, air, and soil pollution. The key advantage of HAp lies in its potential to accommodate a wide variety of anionic and cationic substitutions. Nevertheless, HAp and tricalcium phosphate (TCP) syntheses typically involve the use of chemical precursors containing calcium and phosphorus sources and employ diverse techniques, such as solid-state, wet, and thermal methods or a combination of these processes. Researchers are increasingly favoring natural sources such as bio-waste (eggshells, oyster shells, animal bones, fish scales, etc.) as viable options for synthesizing HAp. Interestingly, the synthesis route significantly influences the morphology, size, and crystalline phase of calcium phosphates. In this review paper, we highlight both dry and wet methods, which include six commonly used synthesis methods (i.e. solid-state, mechano-chemical, wet-chemical precipitation, hydrolysis, sol-gel, and hydrothermal methods) coupled with the variation in source materials and their influence in modifying the structural morphology from a bulky state to nanoscale to explore the applications of multifunctional calcium phosphates in different formats.

Interband electronic transitions and optical phonon modes in size-dependent multiferroic BiFeO3 nanoparticles

Bismuth ferrite (BiFeO3) multiferroic nanoparticles are synthesized using a low-temperature sol-gel auto-combustion technique. The phase purity is confirmed from X-ray diffraction (XRD) measurements and microstructural, electronic, and optical studies are correlated with the particle size of the bismuth ferrite nanostructured material. We demonstrated bandgap tunability from 2.22 to 1.93 eV with an average crystallite size from 42 to 24.42 nm following the inverse quantum confinement effect dominated by the lattice strain. The degenerate d-d electronic transitions 6A1g → 4T1g and 6A1g → 4T2g from iron dominate in these nanoparticles. The decrease in the energy band gap and the corresponding red shift in the d-d charge transfer transition energies with reduced average crystallite size are attributed to the increased lattice strain and reduced unit cell volume.

Magnesium Oxide (MgO) Nanoparticles: Synthetic Strategies and Biomedical Applications

In recent times, there has been considerable interest among researchers in magnesium oxide (MgO) nanoparticles, due to their excellent biocompatibility, stability, and diverse biomedical uses, such as antimicrobial, antioxidant, anticancer, and antidiabetic properties, as well as tissue engineering, bioimaging, and drug delivery applications. Consequently, the escalating utilization of magnesium oxide nanoparticles in medical contexts necessitates the in-depth exploration of these nanoparticles. Notably, existing literature lacks a comprehensive review of magnesium oxide nanoparticles’ synthesis methods, detailed biomedical applications with mechanisms, and toxicity assessments. Thus, this review aims to bridge this gap by furnishing a comprehensive insight into various synthetic approaches for the development of MgO nanoparticles. Additionally, it elucidates their noteworthy biomedical applications as well as their potential mechanisms of action, alongside summarizing their toxicity profiles. This article also highlights challenges and future prospects for further exploring MgO nanoparticles in the biomedical field. Existing literature indicates that synthesized magnesium oxide nanoparticles demonstrate substantial biocompatibility and display significant antibacterial, antifungal, anticancer, and antioxidant properties. Consequently, this review intends to enhance readers’ comprehension regarding recent advancements in synthesizing MgO nanoparticles through diverse approaches and their promising applications in biomedicine.

Investigation of Interface Characteristics and Physisorption Mechanism in Quantum Dots/TiO2 Composite for Efficient and Sustainable Photoinduced Interfacial Electron Transfer

Owing to their superior stability compared to those of conventional molecular dyes, as well as their high UV-visible absorption capacity, which can be tuned to cover the majority of the solar spectrum through size adjustment, quantum dot (QD)/TiO2 composites are being actively investigated as photosensitizing components for diverse solar energy conversion systems. However, the conversion efficiencies and durabilities of QD/TiO2-based solar cells and photocatalytic systems are still inferior to those of conventional systems that employ organic/inorganic components as photosensitizers. This is because of the poor adsorption of QDs onto the TiO2 surface, resulting in insufficient interfacial interactions between the two. The mechanism underlying QD adsorption on the TiO2 surface and its relationship to the photosensitization process remain unclear. In this study, we established that the surface characteristics of the TiO2 semiconductor and the QDs (i.e., surface defects of the metal oxide and the surface structure of the QD core) directly affect the QD adsorption capacity by TiO2 and the interfacial interactions between the QDs and TiO2, which relates to the photosensitization process from the photoexcited QDs to TiO2 (QD* → TiO2). The interfacial interaction between the QDs and TiO2 is maximized when the shape/thickness-modulated triangular QDs are composited with defect-rich anatase TiO2. Comprehensive investigations through photodynamic analyses and surface evaluation using X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and photocatalysis experiments collectively validate that tuning the surface properties of QDs and modulating the TiO2 defect concentration can synergistically amplify the interfacial interaction between the QDs and TiO2. This augmentation markedly improved the efficiency of photoinduced electron transfer from the photoexcited QDs to TiO2, resulting in significantly increased photocatalytic activity of the QD/TiO2 composite. This study provides the first in-depth characterization of the physical adhesion of QDs dispersed on a heterogeneous metal-oxide surface. Furthermore, the prepared QD/TiO2 composite exhibits exceptional adsorption stability, resisting QD detachment from the TiO2 surface over a wide pH range (pH = 2-12) in aqueous media as well as in nonaqueous solvents during two months of immersion. These findings can aid the development of practical QD-sensitized solar energy conversion systems that require the long-term stability of the photosensitizing unit.

Mechanistic Approach on the Pulmonary Oxido-Inflammatory Stress Induced by Cobalt Ferrite Nanoparticles in Rats

Cobalt ferrite nanoparticles (CFN) are employed in data storage, imaging, medication administration, and catalysis due to their superparamagnetic characteristics. The widespread use of CFN led to significantly increased exposure to people and the environment to these nanoparticles. Until now, there is not any published paper describing the adverse effect of repeated oral intake of this nanoformulation on rats' lungs. So, the current research aims to elucidate the pulmonary toxicity prompted by different concentrations of CFN in rats as well as to explore the mechanistic way of such toxicity. We used 28 rats that were divided equally into 4 groups. The control group received normal saline, and the experimental groups received CFN at dosage levels 0.05, 0.5, and 5 mg/kg bwt. Our findings revealed that CFN enhanced dose-dependent oxidative stress manifested by raising in the MDA levels and declining in the GSH content. The histopathological examination revealed interstitial pulmonary inflammation along with bronchial and alveolar damage in both 0.5 and 5 mg CFN given groups. All these lesions were confirmed by the immunohistochemical staining that demonstrated strong iNOS and Cox-2 protein expression. There was also a significant upregulation of TNFα, Cox-2, and IL-1β genes with downregulation of IL-10 and TGF-β genes. Additionally, the group receiving 0.05 mg CFN did not exhibit any considerable toxicity in all measurable parameters. We concluded that the daily oral intake of either 0.5 or 5 mg CFN, but not 0.05 mg, could induce pulmonary toxicity via NPs and/or its leached components (cobalt and iron)-mediated oxido-inflammatory stress. Our findings may help to clarify the mechanisms of pulmonary toxicity generated by these nanoparticles through outlining the standards for risk assessment in rats as a human model.

Spectroscopic studies of metastable tetragonal ZrO2 nanocrystals

This study delves into an examination of the structural and luminescent properties of zirconium dioxide (ZrO2) synthesized via the solid-state combustion method. Nitrates are harnessed as the oxidizing agent, while glycine serves as the fuel. Two distinct compositions are explored: a stoichiometric 1:1 ratio and a fuel-enriched 1:2 ratio. The structural analysis, employing X-ray diffraction and Raman spectroscopy, predominantly manifests a tetragonal structural phase in both samples; however, a minor monoclinic phase has also been observed in the former sample. The band gap was found to be 4.50 eV and 4.28 eV for ZrO2 synthesized in stoichiometric ratio and a fuel-enriched ratio respectively. The samples also show defects assisted photoluminescence in both the samples. The thermoluminescence of samples were investigated after irradiating the samples with UV and gamma rays for different doses. The TL curves manifest a shift towards lower temperatures at higher doses. . Significantly, the sample prepared with a 1:1 nitrate-fuel ratio exhibits a more pronounced overall TL intensity. In conclusion, our findings imply that the formation of the tetragonal phase may be influenced by strain energy, rather than being solely ascribed to size effects and oxygen vacancies within the lattice.

Electro-Oxidation Reaction of Methanol over La2-xSrxNi1-y(Mn/Fe/Co)yO4+δ Ruddlesden-Popper Oxides

Solution combustion-synthesized Ruddlesden-Popper oxides La1.4Sr0.6Ni0.9(Mn/Fe/Co)0.1O4+δ were explored for the methanol electro-oxidation reaction. With optimal doping of Sr2+ in the A site and Co2+ in the B site, Ni3+ with t2g6 d x 2 - y 2 1 configuration in La1.4Sr0.6Ni0.9Co0.1O4+δ exhibited a tetragonal distortion with compression in axial bonds and elongation in equatorial bonds. This structural modification fostered an augmented overlap of d z 2 orbitals with axial O 2p orbitals, leading to a heightened density of states at the Fermi level. Consequently, this facilitated not only elevated electrical conductivity but also a noteworthy reduction in the charge transfer resistance. These effects collectively contributed to the exceptional methanol oxidation activity of La1.4Sr0.6Ni0.9Co0.1O4+δ, as evidenced by an impressive current density of 21.4 mA cm-2 and retention of 95% of initial current density even after 10 h of prolonged reaction. The presence of Ni3+ further played a pivotal role in the creation of NiOOH, a crucial intermediate species, facilitated by the presence of surface oxygen vacancies. These factors synergistically enabled efficient methanol oxidation. In summary, our present study not only yields substantial insights but also paves the way for a novel avenue to fine-tune the activity of Ruddlesden-Popper oxides for the successful electro-oxidation of methanol.

Heteroatom-modulated NiCo2O4 apparent energy activation of PMS for tetracycline removal: Mechanism and toxicity analysis

Heteroatom doping to reconfigure the electronic structure of heterogeneous catalysts is expected to lead to the development of advanced oxidation water purification materials with superior performance and greater stability. Herein, a series of catalysts with different elemental doping was developed by a simple and environmentally friendly one-step self-propagating combustion method to remove Tetracycline (TC). After S-doping, the normalized kinetic constant of TC was significantly increased from 30.49 to 159.41 min-1M-1 within 30 min, which is even higher than most recent heterogeneous catalysts. The prepared S-doped NiCo2O4 (NCO-S) exhibits an extremely promising catalytic performance for oxidation (92.8 %) and mineralization (65.9 %) of TC in a wide pH range (3-11). The resistance to interference is excellent for inorganic ions and even in real water samples. Quenching experiments, electron paramagnetic resonance (EPR), and electrochemical analyses demonstrated that the non-radical oxidation pathway, including electron transfer and 1O2, dominated the degradation process after S doping. It is speculated that possible intermediates and toxicological studies are discussed, finding that the overall degradation process is moving towards low toxicity to reveal prospects for large-scale applications. This work not only provides a way to remove TC, but may also inspire the design of more efficient and stable materials for water treatment and other applications.

Influence of Polycyclic Aromatic Compounds and Oxidation States of Soot Organics on the Metabolome of Human-Lung Cells (A549): Implications for Vehicle Fuel Selection

Decades of research have established the toxicity of soot particles resulting from incomplete combustion. However, the unique chemical compounds responsible for adverse health effects have remained uncertain. This study utilized mass spectrometry to analyze the chemical composition of extracted soot organics at three oxidation states, aiming to establish quantitative relationships between potentially toxic chemicals and their impact on human alveolar basal epithelial cells (A549) through metabolomics-based evaluations. Targeted analysis using MS/MS indicated that particles with a medium oxidation state contained the highest total abundance of compounds, particularly oxygen-containing polycyclic aromatic hydrocarbons (OPAHs) composed of fused benzene rings and unsaturated carbonyls, which may cause oxidative stress, characterized by the upregulation of three specific metabolites. Further investigation focused on three specific OPAH standards: 1,4-naphthoquinone, 9-fluorenone, and anthranone. Pathway analysis indicated that exposure to these compounds affected transcriptional functions, the tricarboxylic acid cycle, cell proliferation, and the oxidative stress response. Biodiesel combustion emissions had higher concentrations of PAHs, OPAHs, and nitrogen-containing PAHs (NPAHs) compared with other fuels. Quinones and 9,10-anthraquinone were identified as the dominant compounds within the OPAH category. This knowledge enhances our understanding of the compounds contributing to adverse health effects observed in epidemiological studies and highlights the role of aerosol composition in toxicity.

Controlling Metal-Oxide Reducibility for Efficient C-H Bond Activation in Hydrocarbons

Knowing the structure of catalytically active species/phases and providing methods for their purposeful generation are two prerequisites for the design of catalysts with desired performance. Herein, we introduce a simple method for precise preparation of supported/bulk catalysts. It utilizes the ability of metal oxides to dissolve and to simultaneously precipitate during their treatment in an aqueous ammonia solution. Applying this method for a conventional VOx -Al2 O3 catalyst, the concentration of coordinatively unsaturated Al sites was tuned simply by changing the pH value of the solution. These sites affect the strength of V-O-Al bonds of isolated VOx species and thus the reducibility of the latter. This method is also applicable for controlling the reducibility of bulk catalysts as demonstrated for a CeO2 -ZrO2 -Al2 O3 system. The application potential of the developed catalysts was confirmed in the oxidative dehydrogenation of ethylbenzene to styrene with CO2 and in the non-oxidative propane dehydrogenation to propene. Our approach is extendable to the preparation of any metal oxide catalysts dissolvable in an ammonia solution.

Persistent luminescent nanophosphors for applications in cancer theranostics, biomedical, imaging and security

The extraordinary and unique properties of persistent luminescent (PerLum) nanostructures like storage of charge carriers, extended afterglow, and some other fascinating characteristics like no need for in-situ excitation, and rechargeable luminescence make such materials a primary candidate in the fields of bio-imaging and therapeutics. Apart from this, due to their extraordinary properties they have also found their place in the fields of anti-counterfeiting, latent fingerprinting (LPF), luminescent markings, photocatalysis, solid-state lighting devices, glow-in-dark toys, etc. Over the past few years, persistent luminescent nanoparticles (PLNPs) have been extensively used for targeted drug delivery, bio-imaging guided photodynamic and photo-thermal therapy, biosensing for cancer detection and subsequent treatment, latent fingerprinting, and anti-counterfeiting owing to their enhanced charge storage ability, in-vitro excitation, increased duration of time between excitation and emission, low tissue absorption, high signal-to-noise ratio, etc. In this review, we have focused on most of the key aspects related to PLNPs, including the different mechanisms leading to such phenomena, key fabrication techniques, properties of hosts and different activators, emission, and excitation characteristics, and important properties of trap states. This review article focuses on recent advances in cancer theranostics with the help of PLNPs. Recent advances in using PLNPs for anti-counterfeiting and latent fingerprinting are also discussed in this review.

Cerium oxide nanoparticles: Synthesis methods and applications in wound healing

Wound care and treatment can be critical from a clinical standpoint. While different strategies for the management and treatment of skin wounds have been developed, the limitations inherent in the current approaches necessitate the development of more effective alternative strategies. Advances in tissue engineering have resulted in the development of novel promising approaches for accelerating wound healing. The use of various biomaterials capable of accelerating the regeneration of damaged tissue is critical in tissue engineering. In this regard, cerium oxide nanoparticles (CeO2 NPs) have recently received much attention because of their excellent biological properties, such as antibacterial, anti-inflammatory, antioxidant, and angiogenic features. The incorporation of CeO2 NPs into various polymer-based scaffolds developed for wound healing applications has led to accelerated wound healing due to the presence of CeO2 NPs. This paper discusses the structure and functions of the skin, the wound healing process, different methods for the synthesis of CeO2 NPs, the biological properties of CeO2 NPs, the role of CeO2 NPs in wound healing, the use of scaffolds containing CeO2 NPs for wound healing applications, and the potential toxicity of CeO2 NPs.

Solution Combustion Synthesis of Ni-Based Nanocatalyst Using Ethylenediaminetetraacetic Acid and Nickel-Carbon Nanotube Growth Behavior

We studied the influence of the ethylenediaminetetraacetic acid (EDTA) content used as combustion fuel when fabricating nickel oxide (NiO) nanocatalysts via solution combustion synthesis, as well as the growth behavior of carbon nanotubes (CNTs) using this catalyst. Nickel nitrate hexahydrate (Ni(NO3)2∙6H2O) was used as the metal precursor (an oxidizer), and the catalysts were synthesized by adjusting the molar ratio of fuel (EDTA) to oxidizer in the range of 1:0.25 to 2.0. The results of the crystal structure analysis showed that as the EDTA content increased beyond the chemical stoichiometric balance with Ni(NO3)2∙6H2O (F/O = 0.25), the proportion of Ni metal within the catalyst particles decreased, and only single-phase NiO was observed. Among the synthesized catalysts, the smallest crystallite size was observed with a 1:1 ratio of Ni ions to EDTA. However, an increase in the amount of EDTA resulted in excessive fuel supply, leading to an increase in crystallite size. Microstructure analysis revealed porous NiO agglomerates due to the use of EDTA, and differences in particle growth based on the fuel ratio were observed. We analyzed the growth behavior of CNTs grown using NiO nanocatalysts through catalytic chemical vapor deposition (CCVD). As the F/O ratio increased, it was observed that the catalyst particles grew excessively beyond hundreds of nanometers, preventing further CNT growth and leading to a rapid termination of CNT growth. Raman spectroscopy was used to analyze the structural characteristics of CNTs, and it was found that the ID/IG ratio indicated the highest CNT crystallinity near an F/O ratio of 1:1.

Solution Combustion Synthesis of High-Performance Nano-LiFePO4/C Cathode Material from Cost-Effective Mixed Fuels

Solution combustion synthesis (SCS) is considered as an efficient and energy-saving method for preparing LiFePO4/C composite material with the nanostructure (Nano-LiFePO4/C). In this study, Nano-LiFePO4/C cathode material was prepared using SCS using a cost-effective combination of urea and sorbitol as mixed fuels. The effect of mixed fuels on combustion behavior and microstructure as well as on electrochemical performance was studied using XRD, BET, SEM, TEM, and electrochemical characterization methods. Multiple characterization results indicated that the maximum temperature (Tm) and particle size were influenced by the usage of urea and sorbitol. The sample derived under optimum conditions exhibits a mesoporous nanostructure with a large surface specific area and attractive electrochemical performance with a discharge capacity of 153.5 mAh/g at 0.1 C, which shows strong potential for commercial applications in the future.

High-entropy oxides: an emerging anode material for lithium-ion batteries

High entropy oxides (HEOs) have gained significant attention in multiple research fields, particularly in reversible energy storage. HEOs with rock-salt and spinel structures have shown excellent reversible capacity and longer cycle spans compared to traditional conversion-type anodes. However, research on HEOs and their electrochemical performance remains at an early stage. In this highlight, we review recent progress on HEO materials in the field of lithium-ion batteries (LIBs). Firstly, we introduce the synthesis methods of HEOs and some factors that affect the morphology and electrochemical properties of the synthesized materials. We then elaborate on the structural evolution of HEOs with rock-salt and spinel structures in lithium energy storage and summarize the relationship between morphology, pseudocapacitance effect, oxygen vacancy, and electrochemical performance. In the end, we give the challenges of HEO anodes for LIBs and present our opinions on how to guide the further development of HEOs for advanced anodes.

Synthesis and feasibility studies of doping U at Ti site of Y2Ti2O7 as a radioactive waste immobilization matrix

In pursuit of clean and green nuclear energy one of the major challenges is to effectively immobilize the nuclear waste. In this context A2B2O7 type pyrochlore owing to its structural flexibility, ability to accommodate ions at both A/B-sites and high radiation tolerance has demonstrated excellent capability to store highly radioactive actinide ions. To fill the major gap area of actinide doping at the B site we have taken up the challenge of doping uranium ions at the Ti site of Y2Ti2O7 type pyrochlore. An yttria titanate (Y2Ti2-xUxO7; x = 0.05, 0.075, 0.1, 0.2, and 0.3) based matrix with uranium doped at the Ti site was synthesized using a simple gel combustion route under an air atmosphere. Rietveld refined X-ray diffraction (XRD) demonstrated that Y2Ti2O7 can accommodate U up to 5 mol% in the Ti site without any phase separation, which was further confirmed using Raman spectroscopy. Y2Ti2O7 based matrices are found to be radiation stable up to 1000 kGy and at the same time they are moderately thermally stable and on a par with the values reported for pyrochlores. Uranium in Y2Ti2O7 stabilizes in +6 oxidation state in the form of uranyl ion distributed near and far off from titanium vacancies with distinct excited state lifetime. This work could provide a smart and strategic way for selecting a suitable advanced ceramic matrix for immobilization of high level waste with additional and important information on solubility limit, actinide speciation, radiation/thermal stability, actinide concentration, etc.

Structural, morphological, and optical characteristics of Gd2 Si2 O7 :Dy3+ nanophosphors for WLEDs

Yellowish-white light-emitting Gd2-x Si2 O7 :xDy3+ (x = 1-5 mol%) nanophosphors were prepared using a solution combustion synthesis method. Fluorescence spectrophotometry and X-ray diffraction measurements were performed to scrutinize the optical performances and phase recognition of the designated nanophosphors. The outcomes specified that the prepared phosphors were crystallized into a triclinic phase with a P-1 space group. As the concentration of Dy3+ ions was increased, the unit-cell volume decrease proportionally due to the replacement of large-sized Gd3+ by small-sized Dy3+ ions. Under ultraviolet excitation at 349 nm, emission spectra consisted of two pronounced emission lines at ~482 nm (blue line), ~578 nm (yellow line), and a relatively weaker emission at ~670 nm (red line) due to 4 F9/2 →6 H15/2 , 4 F9/2 →6 H13/2 , and 4 F9/2 →6 H11/2 intraconfigurational transitions of Dy3+ ions, respectively. The evidence about the site symmetry around Dy3+ ions was examined by considering the ratio of yellow-to-blue emission intensity. The observed critical distance (Rc ) value was ~20.56 Å (≫5 Å), which signified that energy transfer primarily occurred due to multipolar interaction. The obtained coordinates were close to the white region of the Commission Internationale de l'Éclairage chromaticity diagram, which marked a significant milestone in the development of white light-emitting diodes.

Optically amended biosynthesized crystalline copper-doped ZnO for enhanced antibacterial activity

The emergence and re-emergence of antibiotic-resistant bacteria is a potential threat to treating infectious diseases. This study employed a nanometer-scale green synthesis using an extract of Solanum incanum leaves to obtain nanoparticles (NPs) and nanocomposites (NCs) possessing antibacterial properties. The FESEM-EDS elemental mapping analysis proved the novelty of the green synthesis approach in synthesizing a copper-doped ZnO NCs with good dopant distribution. The crystallinity and ZnO bandgap were adjusted by extrinsic copper doping in the ZnO lattice. The optical property adjustments from 3.04 to 2.97 eV for indirect Kubelka-Munk functions were confirmed from DRS-UV-vis analysis. The dopant inclusion in the host lattice was also confirmed by the angle shift on the XRD pattern analysis relative to single ZnO. In addition to doping, the XRD pattern analysis also showed the development of CuO crystals. The lattice fringe values from HRTEM analysis confirmed the existence of both CuO and ZnO crystals with local heterojunctions. Doping and heterojunctions have crucial values in charge transfer and visible light harvesting behaviour, as proved by the PL analysis. The synergistic effects of the doped NCs showed greater antibacterial activity against both Gram-positive and Gram-negative bacteria as a result of more ROS generation through the bacteria-cell-catalyst interaction and release of metal ions. The antioxidant potential of the doped NCs was found to be higher than that of single NPs, using the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging assay and is expected to impart protective effects to the host cells by scavenging destructive free radicals. Thus, the overall analysis leads to the conclusion that the potentiality of synthesized materials has a future outlook for biological applications, especially in the development of antimicrobials to combat antibiotic-resistant bacteria and microbes.