Scavenger-Supported Photocatalytic Evidence of an Extended Type I Electronic Structure of the TiO2@Fe2O3 Interface

Core-shell composite nanoarchitectonics of TiO2@NiCo2S4 via thermal decomposition approach for photodegradation of congo red

In the present work, TiO2@NiCo2S4 core-shell nanocomposites have been successfully synthesized using a thermal decomposition approach using nickel acetyl acetonate and cobalt acetyl acetonate as metal salts and thiourea as source of sulfur in the presence of TiO2 microspheres in diphenyl ether at about 200 °C in air aiming at their application in photodegradation of congo red (CR), a dye pollutant. The thickness of NiCo2S4 nanoparticles (shell) could be varied using different concentrations of reagents. Various analytical techniques were used to characterize the TiO2@NiCo2S4 core-shell nanocomposites including powder XRD, FE-SEM, XPS, TEM and EDX confirming their successful synthesis. The synthesized core-shell nanocomposites exhibit notable photocatalytic activity towards degradation of an aqueous solution of congo red under sunlight. The photocatalytic degradation efficiency of TiO2@NiCo2S4 nanocomposites is better than that of TiO2-based nanocomposites, metal sulfide nanoparticles and other nanocomposites reported in the literature.

Unveiling the Quassia indica derived synthesis of Co3O4/ZnO nanohybrids for efficient dye degradation and cytotoxicity assessment

While there are exciting possibilities in nanotechnology, creating environmentally safe nanoparticles with a variety of uses in photocatalysis and biomedicine continues to be a significant issue. This work addresses the gap by introducing Quassia indica leaf extract as a bio reductant and stabilizer in the green synthesis of cobalt oxide-zinc oxide nanoparticles (QI: Co3O4/ZnO NP). The synthesized nanoparticles were characterized using various techniques, including UV-visible spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (EDX). The existence of hexagonal zinc oxide and cubic cobalt oxide phases in the synthesized nanoparticles was verified by XRD analysis. The elemental composition was confirmed by EDX, which showed that oxygen, zinc, and cobalt were present. The average hydrodynamic diameter of 244.5 d. nm was found via DLS measurements, indicating well dispersed nanoparticles. Under UV light irradiation, photocatalytic activity of QI: Co3O4/ZnO NP was assessed for the degradation of textile dyes (Reactive Blue-222, Reactive Blue-220, Reactive Red-120, and Reactive Yellow-145). Phytotoxicity tests were conducted to examine the possible environmental impact of the deteriorated dye solution, revealing promising results in mitigating the detrimental impact of industrial dyes. QI: Co3O4/ZnO NP was also assessed for cytotoxicity studies in DLA and EAC cells which showed a concentration-dependent cytotoxic effect. The research outcomes emphasize the significant potential of these nanoparticles in diverse arena by offering a sustainable and efficacious resolution to the present-day problems.

Synergistic Removal of Diclofenac via Adsorption and Photocatalysis Using a Molecularly Imprinted Core-Shell Photocatalyst

In this work, a newly developed magnetic molecularly imprinted Fe3O4/SiO2/TiO2/MIP photocatalyst with diclofenac (DIC) as the template was prepared by microwave-assisted synthesis. The molecularly imprinted TiO2 layer has specific cavities designed for the DIC target molecule (imprint), resulting in a synergistic effect of extraction by adsorption and photocatalysis. For reference, non-imprinted magnetic nanoparticles (Fe3O4/SiO2/TiO2) were prepared using the same procedure. The obtained particles were characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), SEM-EDX, vibrating-sample magnetometry (VSM) and diffuse reflectance spectroscopy (DRS). Specific surface area, pore volume and pore size distribution were evaluated using Brunauer-Emmett-Teller (BET) adsorption-desorption isotherms. The synergistic effect of adsorption and photocatalysis as well as the kinetics and mechanism of DIC degradation using Fe3O4/SiO2/TiO2/MIP and Fe3O4/SiO2/TiO2 were determined and analysed. The adsorption efficiency of Fe3O4/SiO2/TiO2/MIP for DIC (10 mg dm-3) was around 86% after 60 min. The DIC (10 mg dm-3) removal efficiency of Fe3O4/SiO2/TiO2/MIP was around 80% after 30 min adsorption and 120 min of reaction under both UV-A- and solar-simulated light irradiation.

BiFe0.5Cr0.5O3 nanocatalysts for sustainable solar-light-driven purification of pharmaceutical wastewater

Pharmaceutical wastewater contamination, particularly from antibiotics, poses severe environmental and health risks due to antibiotic-resistant bacteria and the inefficacy of conventional treatments. In this study, BiFe0.5Cr0.5O3 (BFCO) nanoparticles were synthesized via the sol-gel method and investigated as a visible-light-driven photocatalyst for ciprofloxacin (CIP) and levofloxacin (LFX) degradation under solar irradiation. The structural analysis confirmed a single-phase perovskite structure with Cr3+ incorporation, enhancing charge separation and visible-light absorption. The presence of oxygen vacancies, identified through XPS and Raman spectroscopy, played a crucial role in charge transfer and reactive oxygen species (ROS) generation. Comprehensive electrochemical and photoelectrochemical analyses, including CV, LSV, and EIS, confirmed enhanced charge transport and reduced interfacial resistance under illumination. BFCO, with a bandgap of 1.87 eV, exhibited efficient solar energy utilization, achieving 70.35% CIP and 94% LFX degradation within 240 minutes, following pseudo-first-order kinetics. The activation energy decreased from 33.61 ± 5.88 to 19.69 ± 3.94 kJ mol-1 K-1, confirming enhanced catalytic efficiency. An apparent quantum yield (AQY) of 34.9% for LFX further underscored its superior activity. Scavenger studies identified electron (e-) and superoxide (˙O2 -) radicals as key ROS driving antibiotic degradation, while oxygen vacancies improved charge separation and ROS formation. Reusability tests confirmed BFCO's stability across multiple cycles, maintaining its structural, morphological, and optical integrity. The degradation mechanism involves solar-induced electron-hole pair generation, charge transfer to oxygen vacancies, and subsequent redox reactions that break down antibiotics into non-toxic byproducts. The synergistic effects of Cr substitution, oxygen vacancies, and mixed-valence states significantly enhanced photocatalytic efficiency, demonstrating BFCO's potential for large-scale environmental remediation.

Simulation and experimentation of iron-doped liquid metal-based gallium oxide photocatalysts for environmental applications harnessing solar energy

Gallium-based liquid metals (GLM) have emerged as promising materials for cutting-edge technologies. However, their increased use raises environmental concerns. Sustainable strategies, such as using them as nanophotocatalyst precursors, can help mitigate these impacts. In this work, gallium oxides doped with different atomic ratios of Ga:Fe (100:0, 80:20, 70:30, and 50:50) were synthesized from GLM, characterized, and evaluated in the degradation of an emergent pollutant (acetaminophen). The study considers theoretical modeling through the density functional theory. The photocatalysts were characterized by different techniques to investigate and corroborate the effect of iron on the structural, optical, and morphological properties. The results showed that Fe content influences the properties of gallium oxides. After Fe doping, the band gap of FeGOx decreases to 3.21-2.78 eV. All materials showed photocatalytic activity in the visible region (k 1 = 0.00324 - 0.00562 min- 1 under visible illumination), reaching 65-80% mineralization under visible light, with similar performances under UVA light, making them suitable for use under solar radiation. Among the synthesized materials, FeGO30 displayed the best structural, optical, and morphological properties. Theoretical and experimental results are consistent. Several experiments were conducted using electron, proton, superoxide, and hydroxyl radical scavengers, suggesting that the reaction mechanism of Ac degradation could occur via HO• radicals or oxidation through holes. Additionally, a band diagram is proposed for the FeGOx materials.

Amino acid-based, sustainable organic nanozyme and integrated sensing platform for histamine detection

Inorganic nanozymes hold promise for biomolecule sensing but face challenges like complex fabrication, toxicity, and low sustainability, limiting their use. To overcome these, a sustainable organic nanozyme (OA nanozyme) was created using amino acids and a biocompatible polymer for effective histamine detection. The OA nanozyme exhibits peroxidase-like activity and was fabricated through a single chelation/polymer entanglement method, enabling rapid production (within 3 h) with uniform morphology (≤100 nm diameter) and a negative surface charge at neutral pH. It shows decent kinetic performance (Km = 0.009 mM for H2O2) and biocompatibility, making it suitable for biological applications. The OA nanozyme achieved high sensitivity for histamine detection (LOD: 21.37 pgmL-1) with excellent selectivity and specificity against related molecules. The system's ability to detect histamine in real food samples (e.g., spinach) was also confirmed. These findings indicate that the OA nanozyme holds significant potential for broader applications in food safety and quality assurance.

Mechanistic Insights into the Photocatalytic Indigo Carmine Dye Decolorization by Co3O4/TiO2

TiO2 is widely studied as an efficient UV-light photocatalyst for organic compound degradation through reactive oxygen species (ROS) generation. TiO2 can be modified to show photocatalytic activity under visible light illumination by combining with visible-light absorbing metal oxides. Here, we investigated Co3O4/TiO2 composite materials as visible-light absorbing photocatalysts, with various weight loadings of Co3O4, for the decolorization of wastewater pollutant indigo carmine. Under green LED light, 1.4 wt% Co3O4/TiO2 showed the highest decolorization rate compared to other weight loadings and bare TiO2. While UV-Vis spectroscopy indicated that Co3O4/TiO2 composite materials and bare TiO2 cause similar dye decolorization behavior, NMR spectroscopy showed that after 24 h, reaction products were present in the reaction mixture for 1.4 wt% Co3O4/TiO2, while TiO2 showed no reaction products. The lack of photocatalytic activity of Co3O4/zeolite and other Co3O4/oxide composite materials suggests a synergistic effect between Co3O4 and TiO2, where a small amount of Co3O4 enables TiO2 to utilize visible light without compromising the surface area available for ROS creation. Lastly, we emphasize the need to be cautious when drawing conclusions regarding the dye degradation, since we showed that decolorization does not necessarily equate to full degradation, using a unique combination of UV-Vis and nuclear magnetic resonance spectroscopy.

Exploring a metal/base-free porphyrin involving a carboxyl-functionalized pyridine moiety for photocatalytic N-arylation of benzamide validated using RSM

A porphyrin comprising a carboxyl-functionalized pyridine moiety was synthesized and characterized using 1H NMR, 13C NMR, FT-IR, powder-XRD, BET, ICP-MS, SEM and EDAX. The proton level (H0 = 1.19) and energy band gap (1.39 eV) were determined via UV-Vis spectrophotometry. The UV-visible and fluorescence emission spectra indicated the absorption window of the porphyrin photocatalyst with a distinct Soret band at 424 nm and four Q-bands at 517, 558, 595, and 649 nm. The existence of four Q-bands, the powder XRD data and the ICP-MS analysis supported the absence of metal in the porphyrin photocatalyst. The best photocatalytic conditions generated using Box-Behnken design of RSM (0.2 mol% PcCFP, 5 W LED, 1 : 1.2 ArX : ArCONH2, 24 h) were confirmed through the model reaction of benzamide and 1-bromo-4-nitrobenzene. The N-arylation of benzamide was achieved in a custom-built photoreactor at ambient conditions under exposure to 5 W LED light. Different ArX compounds comprising electron-repelling and electron-attracting groups were assessed to test the potential of the photocatalyst. The porphyrin was found to exhibit significant catalytic activity for C-N bond formation, resulting in 21-73% yields of the substituted benzanilide products. The N-arylated benzamide formation was confirmed using 1H NMR, 13C NMR, HR-MS and SC-XRD. Additionally, heteroaryl halides such as 2-bromo-, 3-bromo-, and 4-bromo-pyridine, as well as 2-chloro-4-methylpyridine, were also found to be compatible and provided admirable yields (28-67%). The stability and heterogeneous nature of the porphyrin photocatalyst were confirmed using FT-IR. The stability of the photocatalyst after the sixth run was demonstrated by the slight decline in the yield of the product from 71 to 67%. The formation of an aryl radical was detected using the scavenger TEMPO, which led to the achievement of N-arylated benzamides containing intermediates of industrial drugs.

Indium-Iron Oxide Nanosized Solid Solutions as Photocatalysts for the Degradation of Pollutants under Visible Radiation

A series of solid solutions of indium and iron oxides with different In/Fe ratios (InxFeyO3, with x + y = 2) were synthesized in the form of nanoparticles (diameter of ca. 30-40 nm) with the purpose of generating enhanced photocatalysts with an intermediate band gap compared to those of the monometallic oxides, In2O3 and Fe2O3. The materials were prepared by co-precipitation from an aqueous solution of iron and indium nitrates and extensively characterized with a combination of techniques. XRD analysis proved the formation of the desired InxFeyO3 solid solutions for Fe content in the range 5-25 mol%. UV-Vis absorption analysis showed that the substitution of In with Fe in the crystalline structure led to the anticipated gradual decrease of the band gap values compared to In2O3. The obtained semiconductors were tested as photocatalysts for the degradation of model organic pollutants (phenol and methylene blue) in water. Among the InxFeyO3 solid solutions, In1.7Fe0.3O3 displayed the highest photocatalytic activity in the degradation of the selected probe molecules under UV and visible radiation. Remarkably, In1.7Fe0.3O3 showed a significantly enhanced activity under visible light compared to monometallic indium oxide and iron oxide, and to the benchmark TiO2 P25. This demonstrates that our strategy consisting in engineering the band gap by tuning the composition of InxFeyO3 solid solutions was successful in improving the photocatalytic performance under visible light. Additionally, In1.7Fe0.3O3 fully retained its photocatalytic activity upon reuse in four consecutive cycles.

Photocatalytic applications of covalent organic frameworks: synthesis, characterization, and utility

Photocatalysis has emerged as an energy efficient and safe method to perform organic transformations, and many semiconductors have been studied for use as photocatalysts. Covalent organic frameworks (COFs) are an established class of crystalline, porous materials constructed from organic units that are easily tunable. COFs importantly display semiconductor properties and respectable photoelectric behaviour, making them a strong prospect as photocatalysts. In this review, we summarize the design, synthetic methods, and characterization techniques for COFs. Strategies to boost photocatalytic performance are also discussed. Then the applications of COFs as photocatalysts in a variety of reactions are detailed. Finally, a summary, challenges, and future opportunities for the development of COFs as efficient photocatalysts are entailed.

TiO2-based photocatalysts from type-II to S-scheme heterojunction and their applications

Photocatalysis is a promising sustainable technology to remove organic pollution and convert solar energy into chemical energy. Titanium dioxide has drawn extensive attention in this field owing to its high activity under UV light, good chemical stability, large availability, low price and low toxicity. However, the poor quantum efficiency derived from fast electron/hole recombination, the limited utilization of sunlight, and a weak reducing ability still hinder its practical application. Among the modification strategies of TiO2 to enhance its performance, the construction of heterojunctions with other semiconductors is a powerful and versatile way to maximise the separation of photogenerated charge carriers and steer their transport toward enhanced efficiency and selectivity. Here, the research progress and current status of TiO2 modification are reviewed, focusing on heterojunctions. A rapid evolution of the understanding of the different charge transfer mechanisms is witnessed from traditional type II to the recently conceptualised S-scheme. Particular attention is paid to different synthetic approaches and interface engineering methods designed to improve and control the interfacial charge transfer, and several cases of TiO2 heterostructures with metal oxides, metal sulfides and carbon nitride are discussed. The application hotspots of TiO2-based photocatalysts are summarized, including hydrogen generation by water splitting, solar fuel production by CO2 conversion, and the degradation of organic water pollutants. Hints about less studied and emerging processes are also provided. Finally, the main issues and challenges related to the sustainability and scalability of photocatalytic technologies in view of their commercialization are highlighted, outlining future directions of development.

Additive manufacturing of hollow connected networks for solar photo-Fenton-like catalysis

A 3D-printing approach is used to fabricate green bodies/precursor microarchitectures that, upon annealing, allow the fabrication of hierarchical 3D hollow microarchitectures (3DHMs). The 3DHMs are composed mainly of TiO2 and inorganic stabilizers that enable the production of inorganic cellular units upon thermal annealing at 650 °C. Morphological inspection reveals that the 3D architecture beams comprise TiO2 nanoparticles (NPs). The inner and outer diameters of the hollow beams are ∼80 μm and ∼150 μm, retained throughout the 3D hollow network. A proof-of-concept photo-Fenton reaction is assessed. The 3DHMs are impregnated with α-Fe2O3 NPs to evaluate solar photo-Fenton degradation of organic compounds, such as MB used as control and acetaminophen, an organic pollutant. The optical, structural, and chemical environment characteristics, alongside scavenger analysis, generate insights into the proposed solar photo-Fenton degradation reaction over TiO2 3DHMs loaded with α-Fe2O3. Our work demonstrates newly hollow printed microarchitecture with interconnected networks, which can help direct catalytic reactions.

Investigation of Bi2MoO6/MXene nanostructured composites for photodegradation and advanced energy storage applications

This study presents nanostructured composite Bi2MoO6/MXene heterostructure by using hydrothermal method for photodegradation of the congo-red dye and also for energy storage devices. X-ray diffractometer (XRD), High Resolution Transmission Electron Microscopy (HRTEM), Field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) were performed to examine the structural properties along with surface area and porosity of the material. Due to addition of MXene the larger surface area and improved pore size help to quickly break down additional organic pollutants by adsorbing them. The band gap of Bi2MoO6/MXene nanostructured composite reduced to 2.4 eV suggesting transfer of electrons from VB to CB. Bi2MoO6/MXene exhibits a high (92.3%) photocatalytic degradation rate for a duration of 16 min which was verified using UV-visible spectroscopy, also scavenger test was conducted to ascertain the reactive agent along with the degradation pathway was confirmed by LCMS. Elemental content was also established by using inductively coupled plasma mass spectrometry (ICP-MS). For estimating energy storage capacity cyclic voltammetry (CV) was performed. It was observed Bi2MoO6/MXene nanostructured composite electrodes had specific capacitance of 642.91Fg- 1, power density of 1.24 kWkg- 1, and energy density of 22.32 Whkg- 1 at a current density of 5Ag- 1 also it exhibited 64.42% capacity retention having current density 20 Ag- 1 throughout 10,000 Galvanostatic charge discharge (GCD) cycles. High electrical conductivity of Bi2MoO6/MXene electrode was again examined by Electrochemical impedance spectroscopy (EIS). These findings demonstrate the potential of Bi2MoO6/MXene nanostructured composites in both photodegradation and energy storage applications.

Enhanced Photocatalytic Paracetamol Degradation by NiCu-Modified TiO2 Nanotubes: Mechanistic Insights and Performance Evaluation

Anodic TiO2 nanotube arrays decorated with Ni, Cu, and NiCu alloy thin films were investigated for the first time for the photocatalytic degradation of paracetamol in water solution under UV irradiation. Metallic co-catalysts were deposited on TiO2 nanotubes using magnetron sputtering. The influence of the metal layer composition and thickness on the photocatalytic activity was systematically studied. Photocatalytic experiments showed that only Cu-rich co-catalysts provide enhanced paracetamol degradation rates, whereas Ni-modified photocatalysts exhibit no improvement compared with unmodified TiO2. The best-performing material was obtained by sputtering a 20 nm thick film of 1:1 atomic ratio NiCu alloy: this material exhibits a reaction rate more than doubled compared with pristine TiO2, enabling the complete degradation of 10 mg L-1 of paracetamol in 8 h. The superior performance of NiCu-modified systems over pure Cu-based ones is ascribed to a Ni and Cu synergistic effect. Kinetic tests using selective holes and radical scavengers unveiled, unlike prior findings in the literature, that paracetamol undergoes direct oxidation at the photocatalyst surface via valence band holes. Finally, Chemical Oxygen Demand (COD) tests and High-Resolution Mass Spectrometry (HR-MS) analysis were conducted to assess the degree of mineralization and identify intermediates. In contrast with the existing literature, we demonstrated that the mechanistic pathway involves direct oxidation by valence band holes.

Synthesis of Fe2O3/TiO2 Photocatalytic Composites for Methylene Blue Degradation as a Novel Strategy for High-Value Utilisation of Iron Scales

In this study, novel Fe2O3/TiO2 photocatalytic composites were synthesised by combining traditional oxidation roasting with the sol-gel method, using low-cost metallurgical waste (iron scales) as the raw material. The characterisation results revealed that the oxidised iron scales could be transformed into high-purity and porous Fe2O3 particles through oxidation roasting, thereby providing additional sites for the adsorption process and thus serving as an effective carrier for TiO2-based photocatalytic materials. During the sol-gel process, TiO2 was loaded onto the synthesised Fe2O3 particles, generating core-shell heterostructure Fe2O3/TiO2 photocatalytic composites. Under visible light irradiation for 90 min, the Fe2O3/TiO2 photocatalytic composites achieved a remarkable methylene blue removal rate (97.71%). This reaction process followed the quasi-first-order kinetic model with a rate constant of 0.038 min-1. The results have demonstrated that this combination of various components in the Fe2O3/TiO2 photocatalytic composites improved the adsorption, light utilisation, and charge separation effect of the photocatalysts. Moreover, the material exhibited favourable stability and recyclability, making it a decent candidate for the treatment of wastewater from the biochemical industry. Therefore, this study provides a new strategy for improving the photocatalytic activity of TiO2 and expanding the high value-added utilisation of iron scales.

MgO Nanoparticles as a Promising Photocatalyst towards Rhodamine B and Rhodamine 6G Degradation

The increasing global requirement for clean and safe drinking water has necessitated the development of efficient methods for the elimination of organic contaminants, especially dyes, from wastewater. This study reports the synthesis of magnesium oxide (MgO) nanoparticles via a simple precipitation approach and their thorough characterization using various techniques, including XRD, FT-IR, XPS, TGA, DLS, and FESEM. Synthesized MgO nanoparticles' photocatalytic effectiveness was evaluated towards rhodamine B and rhodamine 6G degradation under both UV and visible light irradiation. The results indicated that the MgO nanoparticles possess a face-centered cubic structure with enhanced crystallinity and purity, as well as an average crystallite size of approximately 3.20 nm. The nanoparticles demonstrated a significant BET surface area (52 m2/g) and a bandgap value equal to 5.27 eV. Photocatalytic experiments indicated complete degradation of rhodamine B dye under UV light within 180 min and 83.23% degradation under visible light. For rhodamine 6G, the degradation efficiency was 92.62% under UV light and 38.71% under visible light, thus verifying the MgO catalyst's selectivity towards degradation of rhodamine B dye. Also, reusability of MgO was investigated for five experimental photocatalytic trials with very promising results, mainly against rhodamine B. Scavenging experiments confirmed that •OH radicals were the major reactive oxygen species involved in the photodegradation procedure, unraveling the molecular mechanism of the photocatalytic efficiency of MgO.

Enhanced Photocatalytic Properties and Photoinduced Crystallization of TiO2-Fe2O3 Inverse Opals Fabricated by Atomic Layer Deposition

The use of solar energy for photocatalysis holds great potential for sustainable pollution reduction. Titanium dioxide (TiO2) is a benchmark material, effective under ultraviolet light but limited in visible light utilization, restricting its application in solar-driven photocatalysis. Previous studies have shown that semiconductor heterojunctions and nanostructuring can broaden the TiO2's photocatalytic spectral range. Semiconductor heterojunctions are interfaces formed between two different semiconductor materials that can be engineered. Especially, type II heterojunctions facilitate charge separation, and they can be obtained by combining TiO2 with, for example, iron(III) oxide (Fe2O3). Nanostructuring in the form of 3D inverse opals (IOs) demonstrated increased TiO2 light absorption efficiency of the material, by tailoring light-matter interactions through their photonic crystal structure and specifically their photonic stopband, which can give rise to a slow photon effect. Such effect is hypothesized to enhance the generation of free charges. This work focuses on the above-described effects simultaneously, through the synthesis of TiO2-Fe2O3 IOs via multilayer atomic layer deposition (ALD) and the characterization of their photocatalytic activities. Our results reveal that the complete functionalization of TiO2 IOs with Fe2O3 increases the photocatalytic activity through the slow photon effect and semiconductor heterojunction formation. We systematically explore the influence of Fe2O3 thickness on photocatalytic performance, and a maximum photocatalytic rate constant of 1.38 ± 0.09 h-1 is observed for a 252 nm template TiO2-Fe2O3 bilayer IO consisting of 16 nm TiO2 and 2 nm Fe2O3. Further tailoring the performance by overcoating with additional TiO2 layers enhances photoinduced crystallization and tunes photocatalytic properties. These findings highlight the potential of TiO2-Fe2O3 IOs for efficient water pollutant removal and the importance of precise nanostructuring and heterojunction engineering in advancing photocatalytic technologies.

Effects on structure by spectroscopic investigations, valence state and morphology properties of FeCo-containing SnO2 catalysts for glycerol valorization to cyclic acetals

The effects on the structure, valence state and morphological properties of FeCo-containing SnO2 nanostructured solids were investigated. The physicochemical features were tuned by distinct synthesis routes e.g., sol-gel, coprecipitation and nanocasting, to apply them as catalysts in the glycerol valorization to cyclic acetals. Based on Mössbauer and XPS spectroscopy results, all nanosized FeCoSn solids have Fe-based phases, which contain Co and Sn included in the structure, and well-dispersed Fe3+ and Fe2+ surface active sites. Raman, FTIR and EPR spectroscopies measurements of the spent solids demonstrated structural stability for the sol-gel based solid, which is indeed responsible for the highest catalytic performance, among the nanocasted and coprecipitated counterparts. Morphological and elemental analyses illustrated distinct morphologies and composition on solid surface, depending on the synthesis route. The Fe/Co and Fe/Sn surface ratios are closely related to the catalytic performance. The improved glycerol conversion and selectivities of the solid obtained by sol-gel method was ascribed to the leaching resistance and the Sn action as a structural promoter.

Insight into mechanism of excellent visible-light photocatalytic activity of CuO/MgO/ZnO nanocomposite for advanced solution of environmental remediation

Environmental remediation has sought several innovative ways for the treatment of wastewater and captivated researchers around the globe towards it. Through this study, we aim to proceed with the efforts to foster sustainable and feasible ways for the treatment of wastewater. In this work, we report the sol-gel synthesis of CuO/MgO/ZnO nanocomposite and carry out their systematic characterization with the help of state-of-the-art analytical techniques, such as FTIR, SEM, TEM, PL, XRD, Raman, and AFM. The SEM along with TEM and AFM provided useful insights into the surface morphology of the synthesized nanocomposite on both 2D and 3D surfaces and concluded the well-dispersed behavior of the nanocomposite. The characteristic functional groups responsible for carrying out the reaction of Cu-O, Mg-O, and Zn-O were identified by FTIR spectroscopy. On the other hand, crystal size, dislocation density, and microstrain of the nanocomposite were calculated by XRD. For optical studies, photoluminescence spectroscopy was performed. Once the characterization of the nanocomposite was done, they were eventually treated against the toxic organic dye, methylene blue. The calculated rate constant values of k for CuO was 2.48 × 10-3 min-1, for CuO/MgO (2.04 × 10-3 min-1), for CuO/ZnO (1.82 × 10-3 min-1) and CuO/MgO/ZnO was found to be 2.00 × 10-3 min-1. It has become increasingly evident that nanotechnology can be used in various facets of modern life, and its implementation in wastewater treatment has recently received much attention.

CdS/ZnS core-shell nanorod heterostructures co-deposited with ultrathin MoS2 cocatalyst for competent hydrogen evolution under visible-light irradiation

Hydrogen generation via semiconductor photocatalysts has gained significant attention as a sustainable fuel generation process. To demonstrate the performance of nanoscale core-shell heterostructure in photocatalytic hydrogen production, we have fabricated CdS nanorods coated with ZnS photocatalyst via wet-chemical reaction followed by deposition of ultrathin MoS2 nanosheets by photo reduction process. The effect of ZnS content and suitable amount of MoS2 loading over the visible-light induced photocatalytic hydrogen evolution was examined in Na2S and Na2SO3 aqueous solutions. Interestingly, it is apparent that a close connection (or heterojunction) between CdS and ZnS is believed to easily tunnel the charge carriers to the surplus surface states, making its electrons and holes energetically favourable to transfer from ZnS to MoS2 for photocatalytic reactions and subsequently, enhances the H2 evolution activity in CdS/ZnS type I core-shell heterostructures. The optimal MoS2 concentration is resolved to be 7 mol% and the subsequent visible-light induced H2 generation rate was 13589 μmol h-1g-1, which is 19 and 158 fold higher than pristine CdS and ZnS respectively. The probable photocatalytic mechanism of CdS/ZnS type I core-shell heterostructure with MoS2 cocatalyst is proposed. Our inexpensive and convenient preparation strategy may offer novel prospects in the engineering of desirable nanoheterostructures with better performance.

Facile preparation of environmental benign LED white light active humic acid nanolayer coated titanium dioxide photocatalyst for bisphenol A degradation

Natural organic matter is a mixture of microbial decomposition products widely found in surface and groundwater. These organic materials have great potential as carbon-based precursors for chemical synthesis. This work demonstrated the development of a green photocatalyst via a facile adsorption process that combined colloidal titanium dioxide (TiO2) with humic acid. The resulting photocatalyst was visible light active and able to completely degrade 5 mg/L of BPA within 6 h under the irradiation of energy-efficient LED white light. The first-order kinetic rate constant of the reaction was determined to be 1.7 × 10-2 min-1. The enhanced photocatalytic activity was attributed to the decreased band gap energy and effective charge separation that limits the photogenerated electron-hole recombination. The outcome of this research opened an opportunity for the development of sustainable functional materials using natural organic matter.

Understanding and optimizing the sensitization of anatase titanium dioxide surface with hematite clusters

The presence of hematite (Fe2O3) clusters at low coverage on titanium dioxide (TiO2) surface has been observed to enhance photocatalytic activity, while excess loading of hematite is detrimental. We conduct a comprehensive density functional theory study of Fe2O3clusters adsorbed on the anatase TiO2(101) surface to investigate the effect of Fe2O3on TiO2. Our study shows that TiO2exhibits improved photocatalytic properties with hematite clusters at low coverage, as evidenced by a systematic study conducted by increasing the number of cluster adsorbates. The adsorption of the clusters generates impurity states in the band gap improving light absorption and consequently affecting the charge transfer dynamics. Furthermore, the presence of hematite clusters enhances the activity of TiO2in the hydrogen evolution reaction. The Fe valence mixing present in some clusters leads to a significant increase in H2evolution rate compared with the fixed +3 valence of Fe in hematite. We also investigate the effect of oxygen defects and find extensive modifications in the electronic properties and local magnetism of the TiO2-Fe2O3system, demonstrating the wide-ranging effect of oxygen defects in the combined system.

Second phase Cu2O boosted photocatalytic activity of fluorine doped CuO nanoparticles

The photocatalytic activity of fluorine (F) doped CuO nanoparticles (NPs) prepared employing modified sol-gel process was investigated here in this study. Structural and elemental characterization using XRD and XPS data confirmed successful incorporation of F as dopant. F doping led to lattice distortion and reduced crystallinity with smaller crystallite size while promoting the emergence of Cu2O as the second phase. Morphological analysis showed irregularly shaped, fused particles with a decreasing particle size trend upon doping. Addition of hydrogen peroxide generated hydroxyl radicals (OH˙) under ultra-violet (UV) light, which effectively degrades pollutants by facilitating the photocatalytic kinetics. Photocatalytic activity of all the nanoparticles was examined against Rhodamine B (Rh B) dye and most efficient degradation (97.78%) was observed for 3 mol% F dopant concentration. The emergence of Cu2O phase for doping beyond 1 mol% F doped CuO might be the prime reason to enhance its degradation performance. Conversely, 5 mol% doping caused notable phase changes and decreased degradation rate (88.05%) due to increased recombination rate in presence of metallic copper. The ability of F doped CuO nanoparticles to disintegrate organic contaminants by producing reactive oxygen species when exposed to UV light suggests their potential effectiveness in applications such as dye degradation, water purification, and environmental sustainability.

Green synthesis of CuO/Fe2O3/ZnO ternary composite photocatalyst using grape extract for enhanced photodegradation of environmental organic pollutant

This research delves into fabricating a CuO/Fe2O3/ZnO (CFZ) ternary composite photocatalyst, employing grape extract for its eco-conscious synthesis. The method intricately integrates copper acetate, ferric nitrate, and zinc acetate as precursor compounds, harmonizing them with grape extract serving as a green reducing agent. Meticulous microwave treatment and controlled calcination orchestrate the nuanced formation of the desired composite material. The extensive characterization, involving X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDXS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS), and photoluminescence (PL) spectroscopy, unveils an array of favorable physical, chemical, and optical attributes conducive to proficient photocatalysis. Notably, CFZ-10mc showcases a narrower bandgap of 1.91 eV, which is pivotal for bolstering electron-hole separation, thereby enhancing its photocatalytic efficacy. Assessment of CFZ's performance in degrading Rhodamine B (RhB) under UV irradiation highlights an impressive 88.8% degradation efficiency within 120 min, accompanied by a kinetic rate constant of 1.81 × 10-2 min-1. Deliberation upon crucial parameters, including photocatalyst dosage, initial RhB pH, and reactor energy consumption, introduces the electrical energy per order (EEO) as a notable efficiency metric. CFZ manifests a substantial reduction in operational costs, estimated to be 18.10 times lower than conventional photolysis, signifying an EEO value of 509.17 kWh m-3 order-1. Optimal operational conditions propose a photocatalyst content of 1.5 g L-1 and an initial RhB pH of 7, fostering the prevalence of the primary active species, •OH. These findings illuminate CFZ's potential in mitigating organic pollutants, underlining its pivotal role in sustainable water remediation. Additionally, practical implementation guidelines for leveraging CFZ's capabilities in real-world applications are presented with care and consideration.

Tailoring visible-light active TiO2/cellulose nanocomposites with controlled crystalline structure for enhanced photocatalytic performance

This work involves a green and simple synthesis of TiO2 nanoparticles on cellulose under mild conditions without the need for calcination via hydrolysis of titanium oxysulfate (TiOSO4). The synthesis conditions, such as sulfuric acid concentration (0-10% wt), temperature (70-90 ℃), and time (4-8 h), focused on precisely controlling the structure of TiO2 to enhance its photocatalytic effectiveness under visible light. At a lower 2.5 wt% sulfuric acid concentration, pure anatase was formed on the cellulose, while an increase in the range of 5.0-7.5 wt% sulfuric acid concentration yielded a rutile phase, resulting in a mixed phase of anatase and rutile on the cellulose. The pure rutile phase was found at a low temperature (70 ℃), while increased temperature led to the formation of the anatase phase. These results confirmed that the formation of crystalline TiO2 phase on the cellulose depended on sulfuric acid concentration and temperature for hydrolysis. Additionally, the photocatalytic properties of the obtained materials were evaluated by degradationvisible of Rhodamine B (RhB) under UV and visible light. The findings revealed that the mixed phase (anatase/rutile) of TiO2 on the cellulose demonstrated a superior photocatalytic efficiency (99.2%) compared to pure anatase (85.75%) and rutile (75.08%) when exposed to visible light.

Crystallinity swayed phase transformation and oxygen vacancy formation in TiO2 aerogel photocatalysts

The lack of crystallinity of the aerogel materials has limited their significance which otherwise have found huge potential in wide variety of applications. In current work, we have developed TiO2 aerogels by solid-state gelation method using commercially available P25 and ST-01 (commercial Ishihara TiO2 Powder). The lack of crystallinity in the aerogel framework was resolved via utilizing crystalline TiO2 nanoparticles and the phase transformation was assessed as a function of phase composition. Via controlled solid-state gelation, surface area retention of 88.7% was achieved whereas the rutile-to-anatase weight fraction (WR) was considerably enhanced to 0.50. Interestingly, the phase transformation occurred only in P25, which suggests the mixed phase (anatase + rutile) composition as prerequisite for successful phase transformation. Favorably, TiO2 aerogels imbibe high degree of oxygen vacancies (Vo) responsible for photocatalytic applications. Interestingly, Vo induction is higher for the TiO2 with anatase phase composition (ST-01) followed by the sample with mixed phase composition (P25). The developed TiO2 aerogel photocatalysts were employed to dye degradation of Rhodamine B (RhB) and Methylene Blue (MB). The samples attained 94.8% and 96.8% degradation efficiency within 15 min for RhB and MB with nearly 2-fold improvement in the photocatalytic efficiency compared to parent P25 TiO2 respectively.