The progress and roadmap of metal–organic frameworks for high-performance supercapacitors

A novel two-dimensional metal imidazolate sulphate framework as a versatile platform for enzyme immobilization

The encapsulation of enzymes in ZIF-8 (enzyme@ZIF-8 composites) via co-precipitation has attracted considerable attention. However, enzyme@ZIF-8 composites often exhibit low activity due to the three-dimensional (3D) structural characteristics of ZIF-8 and the protonation of the precursor, 2-methylimidazole (2-MeIm). In this study, a novel 2D catalase@ZIFs(SO4) composite was synthesized as an alternative to the conventional 3D catalase@ZIF-8 composites. The 2D catalase@ZIFs(SO4) composites demonstrated a nine-fold increase in activity and three-fold higher enzyme loading compared to their 3D counterparts. The enhanced catalytic performance is attributed to the 2D structure of the composites and the partial replacement of 2-MeIm with sulfate during enzyme immobilization, which reduces the protonation of 2-MeIm, enhances the hydrophilic microenvironment, and facilitates substrate transfer. Furthermore, compared to free enzymes, the 2D catalase@ZIFs(SO4) composites exhibited an expanded pH tolerance range, superior thermal stability, enhanced resistance to denaturants, and improved storage stability. To validate the concept, glucose oxidase, glutamate oxidase, and phenylalanine ammonia lyase were immobilized using the same approach. All immobilized enzymes demonstrated increased activity relative to the traditional CAT@ZIF-8 composites. This study offers a versatile platform for enzyme encapsulation within ZIF-8 through co-precipitation.

MOFs-Derived Nanoarrays: A Promising Strategy for Next-Generation Supercapacitors

Developing high-performance electrode materials for supercapacitors is one of the keys to improving their overall performance. Metal-organic framework (MOF) is a kind of crystalline porous material with periodic network structure, which is connected by inorganic metal centres and bridged organic ligands through self-assembly. It has the advantages of a large specific surface area, controllable pore size, excellent stability and ordered crystal structure. MOF-derived nanoarrays exhibit excellent electrochemical performance due to their unique structure, rich activation points, close interface contact, and easy electron migration and mass transfer, which have attracted extensive attention in supercapacitor applications. This study mainly reviews the synthesis methods of MOF array electrodes and their applications in supercapacitors. In addition, we also described the challenges and prospects of MOF-derived array electrodes in the application of supercapacitors. This paper has important reference value for the design of MOF-derived array electrodes and advanced energy storage systems. The progress of advanced energy storage systems will further promote the development of sustainable renewable energy, avoid adverse climate and greenhouse effect caused by excessive use of fossil fuels, and achieve a green energy future.

Gas-flow activation of MOFs: unlocking efficient catalysis through dynamic bonding

Metal-organic frameworks (MOFs), characterized by dynamic metal-ligand coordination bonding, have pivotal roles in catalysis, gas storage, and separation processes, owing to their open metal sites (OMSs). These sites, however, are frequently occupied by Lewis-base solvent molecules, necessitating activation to expose the OMSs for practical applications. Traditional thermal activation methods involve harsh conditions, risking structural integrity. This study presents a novel 'gas-flow activation' technique using inert gases like nitrogen and argon to eliminate these coordinating solvent molecules at low temperatures, thereby maintaining the structural integrity of MOFs. We specifically explored this method with HKUST-1, demonstrating that gas-flow activation at mild temperatures is not only feasible but also superior in efficiency compared to the conventional thermal methods. This approach highlights the potential for safer, more efficient activation processes in MOF applications, making it a valuable addition to the repertoire of MOF activation techniques. This activation function of inert gas flow allows HKUST-1 as a catalyst for the hydrogenation of acetophenone even at room temperature. In addition, it is demonstrated that this 'gas-flow activation' is broadly applicable in other MOFs such as MOF-14 and UTSA-76. Furthermore, the findings reveal that dynamic coordination bonding, the repeating transient dissociation-association of solvent molecules at OMSs, are key mechanisms in facilitating this activation, pointing towards new directions for designing activation strategies that prevent structural damage.

Sacrificial MOF-derived MnNi hydroxide for high energy storage supercapacitor electrodes via DFT-based quantum capacitance study

Electrochemical energy storage plays a critical role in the transition to clean energy. With the growing demand for efficient and sustainable energy solutions, supercapacitors have gained significant attention due to their high specific capacitance, rapid charge/discharge capabilities, long lifespan, safe operation across various temperatures, and minimal maintenance needs. This study introduces a novel approach for the synthesis of high-performance supercapacitor electrodes by using MnNi-MOF-74 as a precursor. Bimetallic Mn(OH)₂/Ni(OH)₂ hydroxides (MnNi-x, where x = 2, 6, 12) with tailored morphologies were successfully fabricated by treating MnNi-MOF-74 anchored on nickel foam with different concentrations of KOH. Among the various synthesized samples, MnNi-6 exhibited the best performance, with a remarkable specific capacitance of 4031.51 mF cm⁻2 at 2 mA cm⁻2, attributed to its high surface area of 186 m2/g, optimized particle size, and abundant micropores. Furthermore, MnNi-6 demonstrated exceptional thermal stability, positioning it as a promising candidate for high-temperature supercapacitors. It also exhibited excellent cycling stability, retaining 86.34 % of its capacity after 10,000 cycles at 10 mA cm⁻2, highlighting its remarkable durability. Density functional theory (DFT) calculations were conducted to explore the quantum capacitance of the bimetallic hydroxide. The DFT results revealed electron density near the Fermi level, which directly contributes to the high quantum capacitance of Mn(OH)₂/Ni(OH)₂ with a Mn:Ni molar ratio of 3:1. This work underscores the potential of MOF-derived materials as a promising route for the development of high-performance supercapacitor electrodes, paving the way for future advances in electrochemical energy storage technologies.

Porosity Tunable Metal-Organic Framework (MOF)-Based Composites for Energy Storage Applications: Recent Progress

To solve the energy crisis and environmental issues, it is essential to create effective and sustainable energy conversion and storage technologies. Traditional materials for energy conversion and storage however have several drawbacks, such as poor energy density and inadequate efficiency. The advantages of MOF-based materials, such as pristine MOFs, also known as porous coordination polymers, MOF composites, and their derivatives, over traditional materials, have been thoroughly investigated. These advantages stem from their high specific surface area, highly adjustable structure, and multifunctional nature. MOFs are promising porous materials for energy storage and conversion technologies, according to research on their many applications. Moreover, MOFs have served as sacrificial materials for the synthesis of different nanostructures for energy applications and as support substrates for metals, metal oxides, semiconductors, and complexes. One of the most intriguing characteristics of MOFs is their porosity, which permits space on the micro- and meso-scales, revealing and limiting their functions. The main goals of MOF research are to create high-porosity MOFs and develop more efficient activation techniques to preserve and access their pore space. This paper examines the porosity tunable mixed and hybrid MOF, pore architecture, physical and chemical properties of tunable MOF, pore conditions, market size of MOF, and the latest development of MOFs as precursors for the synthesis of different nanostructures and their potential uses.

MnO/TiO2/C/N-CNTs derived from Mn-doped Ti MOFs for simultaneous detection of catechol and hydroquinone

Mn-doped Ti-based MOFs (MnTi MOFs) were synthesized by a solvothermal method, and calcined at high temperature after being mixed with pre-prepared PPy nanotubes to give MnO/TiO2/C/N-CNTs composites. The composites were studied by SEM, XRD, XPS and FTIR. Based on these composites, a new electrochemical sensor was prepared, which has good electrocatalytic ability for the redox of catechol (CC) and hydroquinone (HQ), and can detect CC and HQ simultaneously. The results showed that the oxidation peak current of CC and HQ increased linearly in the concentration range of 0.50-120.00 μM. The detection limits were 0.033 μM and 0.019 μM, respectively. The constructed sensor has been successfully used for the simultaneous detection of CC and HQ in lake water and tap water, and has a good recovery rate.

Potential and challenges of computing with molecular materials

We are at an inflection point in computing where traditional technologies are incapable of keeping up with the demands of exploding data collection and artificial intelligence. This challenge demands a leap to a new platform as transformative as the digital silicon revolution. Over the past 30 years molecular materials for computing have generated great excitement but continually fallen short of performance and reliability requirements. However, recent reports indicate that those historical limitations may have been resolved. Here we assess the current state of computing with molecular-based materials, especially using transition metal complexes of redox active ligands, in the context of neuromorphic computing. We describe two complementary research paths necessary to determine whether molecular materials can be the basis of a new computing technology: continued exploration of the molecular electronic properties that enable computation and, equally important, the process development for on-chip integration of molecular materials.

Upgrading Structural Conjugation in Three-Dimensional Ni-Based Metal-Organic Frameworks for Promoting Electrical Conductivity and Specific Capacitance

Metal-organic frameworks (MOFs) have emerged as promising candidates for electrochemical energy storage and conversion due to their high specific surface areas, abundant active sites, and excellent chemical and structural tunability. However, the direct utilization of MOFs as electrochemical materials is a challenge because of the poor electroconductivity induced by the insulating nature of most organic linkers. Herein, a conjugated three-dimensional Ni-MOF {Ni(HBTC)(BPE)}n (Ni-BPE) with a 2-fold interpenetrating structure was developed via the coordination polymerization of Ni2+, a H3BTC ligand (1,3,5-benzenetricarboxylic acid), and a vinyl-functionalized bipyridine linker (1,2-di(4-pyridyl)ethylene, BPE). Ni-BPE displayed an enhanced conjugation system compared to analogous and insulated Ni-BPY that is constructed by the Ni-BTC layer and ordinary bipyridine linker (4,4'-bipyridine, BPY). Notably, upgrading structural conjugation promoted a dramatical ∼204 times increase in the electroconductivity of Ni-BPE compared to Ni-BPY. More importantly, Ni-BPE displayed a higher specific capacitance of 633.2 F g-1 (316.6 C g-1) at 1 A g-1, which exhibited a significant ∼1.5-fold enhancement than Ni-BPY. Furthermore, the asymmetric supercapacitor can reach a good energy density of 25.2 Wh kg-1 with a reasonable cycle stability of 71.0% over 5000 cycles. This work provides an effective method for optimizing the structure of insulating MOFs to enhance the electroconductivity and specific capacitance.

Validity of zinc oxide nanoparticles biosynthesized in food wastes extract in treating real samples of printing ink wastewater; prediction models using feed-forward neural network (FFNN)

In the present study, biosynthesized ZnO nanoparticles in food wastewater extract (FWEZnO NPs) was used in the photocatalytic degradation of real samples of printing ink wastewater. FWEZnO NPs were prepared using green synthesis methods using a composite food waste sample (2 kg) consisted of rice 30%, bread 20 %, fruits 10 %, chicken 10 %, lamb 10%, and vegetable 20%. The photocatalysis process was optimized using response surface methodology (RSM) as a function of time (15-180 min), pH 2-10 and FWEZnO NP (20-120 mg/100 mL), while the print ink effluent after each treatment process was evaluated using UV-Vis-spectrophotometer. The behaviour of printing ink wastewater samples for photocatalytic degradation and responses for independent factors were simulated using feed-forward neural network (FFNN). FWEZnO NPs having 62.48 % of the purity with size between 18 and 25 nm semicrystalline nature. The main functional groups were -CH, CH2, and -OH, while lipid, carbon-hydrogen stretching, and amino acids were the main component in FWEZnO NP, which contributed to the adsorption of ink in the initial stage of photocatalysis. The optimal conditions for printing ink wastewater were recorded after 17 min, at pH 9 and with 20 mg/100 mL of FWEZnO NPs, at which the decolorization was 85.62 vs. 82.13% of the predicted and actual results, respectively, with R2 of 0.7777. The most significant factor in the photocatalytic degradation was time and FWEZnO NPs. The FFNN models revealed that FWEZnO NPs exhibit consistency in the next generation of data (large-scale application) with an low errors (R2 0.8693 with accuracy of 82.89%). The findings showing a small amount of catalyst is needed for effective breakdown of dyes in real samples of printing ink wastewater.

Al-Based MOF-Derived Amorphous/Crystalline Heterophase Cobalt Sulfides as High-Performance Supercapacitor Materials

Transition metal sulfides (TMSs) are promising electrode materials due to their high theoretical specific capacitance, but sluggish charge transfer kinetics and an insufficient number of active sites hamper their applications in supercapacitors. In this work, a self-sacrificial template strategy was employed to construct Al-based MOF-derived metal sulfides with an amorphous/crystalline (a/c) heterophase, in which aluminum, nitrogen, and carbon species were evenly coordinated in the amorphous phase. The metal sulfides a/c-Co(Al)S-1 and a/c-Co(Al)S-2, originating from the CAU-1 and CoAl-MOF on NF as self-sacrificial templates, were investigated as electrode materials, respectively, in which the a/c-Co(Al)S-1 showed a more excellent electrochemical performance. Through acid etching CAU-1 using Co(NO3)2 followed by sulfuration, the a/c-Co(Al)S-1 with a unique 3D network structure was constructed, whose unique architecture expanded the interfacial contact with the electrolyte and provided vast active sites, accelerating the charge transportation and ion diffusion. Notably, the a/c-Co(Al)S-1 displayed a high specific charge of 1791.8 C g-1 at 1 A g-1, satisfactory cycle stability, and good rate capability. The corresponding assembled a/c-Co(Al)S-1//AC device delivered a high energy density of 77.1 Wh kg-1 at 800 W kg-1 and good durability (87.4% capacitance retention over 10 000 cycles).

Insights into properties, synthesis and emerging applications of polypyrrole-based composites, and future prospective: A review

Recent advancements in polymer science and engineering underscore the importance of creating sophisticated soft materials characterized by well-defined structures and adaptable properties to meet the demands of emerging applications. The primary objective of polymeric composite technology is to enhance the functional utility of materials for high-end purposes. Both the inherent qualities of the materials and the intricacies of the synthesis process play pivotal roles in advancing their properties and expanding their potential applications. Polypyrrole (PPy)-based composites, owing to their distinctive properties, hold great appeal for a variety of applications. Despite the limitations of PPy in its pure form, these constraints can be effectively overcome through hybridization with other materials. This comprehensive review thoroughly explores the existing literature on PPy and PPy-based composites, providing in-depth insights into their synthesis, properties, and applications. Special attention is given to the advantages of intrinsically conducting polymers (ICPs) and PPy in comparison to other ICPs. The impact of doping anions, additives, and oxidants on the properties of PPy is also thoroughly examined. By delving into these aspects, this overview aims to inspire researchers to delve into the realm of PPy-based composites, encouraging them to explore new avenues for flexible technology applications.

Enzyme hybrid nanoflowers and enzyme@metal-organic frameworks composites: fascinating hybrid nanobiocatalysts

Hybrid nanomaterials have recently emerged as a new interface of nanobiocatalysis, serving as a host platform for enzyme immobilization. Enzyme immobilization in inorganic crystal nanoflowers and metal-organic frameworks (MOFs) has sparked the bulk of scientific interest due to their superior performances. Many breakthroughs have been achieved recently in the preparation of various types of enzyme@MOF and enzyme-hybrid nanoflower composites. However, it is unfortunate that there are few reviews in the literature related to enzyme@MOF and enzyme-hybrid nanoflower composites and their improved synthesis strategies and their applications in biotechnology. In this review, innovative synthetic strategies for enzyme@MOF composites and enzyme-hybrid nanoflower composites are discussed. Enzyme@MOF composites and enzyme-hybrid nanoflower composites are reviewed in terms of biotechnological applications and potential research directions. We are convinced that a fundamental study and application of enzyme@MOF composites and enzyme-hybrid nanoflower composites will be understood by the reader as a result of this work. The summary of different synthetic strategies for enzyme@MOF composites and enzyme-hybrid nanoflower composites and the improvement of their synthetic strategies will also benefit the readers and provide ideas and thoughts in the future research process.

Microwave promoted graft copolymerization of poly(ethylacrylate) onto k-carrageenan for removal of Cd and Ni from aqueous solution

Microwave promoted graft copolymerization of poly (ethyl acrylate) onto kappa-carrageenan in presence of a redox pair (ascorbic acid and potassium persulfate) led to the formation of a novel copolymer hydrogel, kappa-carrageenan-graft-poly (ethylacrylate). By varying the reaction conditions such as the microwave power, reaction time, concentration of kappa-carrageenan, ascorbic acid and persulfate, copolymers of highest percentage grafting was obtained and characterized by FT-IR, SEM, TGA and XRD. The copolymer was evaluated as an adsorbent for the adsorption of Ni(II) and Cd(II). Various adsorption parameters such as contact time, pH, initial metal ion concentration, temperature, electrolyte strength and adsorbent dosage were varied to obtain the optimum conditions for the adsorption. The adsorption data for Cd(II), fitted better for Langmuir and Ni(II), fitted much better for Freundlich adsorption isotherm model. Maximum adsorption obtained for cadmium ions and nickel ions was 308.6 mg/g-1 and 305.8 mg/g-1 respectively. The adsorption of both metal ions followed pseudo second order kinetic model. The positive ΔH values endorsed the adsorption process to be endothermic in nature. The negative values of ΔG indicate the spontaneity of the adsorption process while the positive ΔS values showed that the adsorption of metal ions proceeded with increased randomness at the surface of the copolymer. High recovery percentage of the metal ions from the adsorbent indicates that the copolymer can be used for more adsorption cycles.

Li Salt Assisted Highly Flexible Carbonaceous Ni3N@polyimide Electrode for an Efficient Asymmetric Supercapacitor

This work used a highly flexible, sustainable polyimide tape as a substrate to deposit ductile-natured carbonaceous Ni3N (C/Ni3N@polyimide) material for supercapacitor application. C/Ni3N was prepared using a co-sputtering technique, and this method also provided better adhesion of the electrode material over the substrate, which is helpful in improving bending performance. The ductile behavior of the sputter-grown electrode and the high flexibility of the polyimide tape provide ultimate flexibility to the C/Ni3N@polyimide-based supercapacitor. To achieve optimum electrochemical performance, a series of electrochemical tests were done in the presence of various electrolytes. Further, a flexible asymmetric supercapacitor (NC-FSC) (C/Ni3N//carbon@polyimide) was assembled by using C/Ni3N as a cathode and a carbon thin film as an anode, separated by a GF/C-glass microfiber soaked in optimized 1 M Li2SO4 aqueous electrolyte. The NC-FSC offers a capacitance of 324 mF cm-2 with a high areal energy density of 115.26 μWh cm-2 and a power density of 811 μW cm-2, with ideal bending performance.

Effect of Crystal Morphology on Electrochemical Performances of IRH-2 and IRH-2/PANI Composite for Supercapacitor Electrodes

In the context of recent progress in designing metal-organic framework (MOF)-based supercapacitor electrodes, we report herein the successful growth of two different crystal morphologies of a cerium-based MOF, octahedral crystals named IRH-2-O and elongated square-bipyramidal crystals named IRH-2-ESBP (IRH = Institute de Recherche sur l'Hydrogène). The identical crystal structure of both materials was confirmed by powder X-ray diffraction (PXRD). Furthermore, scanning electron microscopy and energy-dispersive X-ray mapping analysis corroborated this fact and showed the crystal shape variation versus the surface composition of synthesized materials. Fourier transform infrared spectroscopy, UV-vis spectroscopy, and PXRD were used to confirm the purity of pristine MOFs as well as desired MOF//PANI composites. Cyclic voltammetry and electrochemical impedance spectroscopy highlighted the effect of crystal shape on the electrochemical performance of IRH-2 MOFs; the specific capacitance tripled from 43.1 F·g-1 for IRH-2-O to 125.57 F·g-1 for IRH-2-ESBP at 5 mV·s-1. The cycling stability was notably ameliorated from 7 K for IRH-2-O to 20 K for IRH-2-ESBP. Regarding the composites, the cell voltage was notably ameliorated from 1.8 to 1.95 V. However, the electrochemical performance of IRH-2/PANI composites was drastically decreased due to instability in the acidic media. To the best of our knowledge, our work is the first work that related the MOF crystal shape and the electrochemical performance.

Deep eutectic solvent-infused two-dimensional metal-organic framework membranes as quasi-solid-state electrolytes for wearable micro-supercapacitors

The burgeoning field of miniaturized and portable electronic devices calls for novel advances in micro-energy storage technology. Micro-supercapacitors (MSC) stand at the forefront of this endeavour, yet unlocking their full potential necessitates the exploration of high-performance electrolytes. Herein, we introduce a strategy that leverages flexible metal-organic framework (MOF, CuTCPP) nanosheet-based membranes to construct quasi-solid-state electrolytes (QSSEs) and enhance the ionic conductivity and electrochemical performance of deep eutectic solvent (DES)-based MSCs. Owing to the multiple nanochannel pathways provided by the porous MOF nanosheets, the ionic conductivity of DES within the nanochannels exhibits a 13-fold increment compared with its bulk counterpart. Furthermore, we engineered MSC harnessing the CuTCPP-DES system, whose performance surpasses that reported for most of the ionic liquid and 2D material-based MSCs. The areal-specific capacitance was 81.3 mF cm-2 at a current density of 0.1 mA cm-2, and the energy density was 45.17 μW h cm-2 at a power density of 8.559 mW cm-2. Notably, the performance of MSCs remains consistent and unaffected, even when subjected to bending. These findings contribute to the exploration and potential optimization of the inherent benefits of MOFs, thereby presenting a paradigm shift in nanoconfined systems for microscale energy storage applications.

In situ self-assembled macroporous interconnected nanosheet arrays of Ni-1,3,5-benzenetricarboxylate metal - organic framework on Ti mesh as high-performance oxygen evolution electrodes

Highly efficient metal-organic framework (MOF)-based oxygen evolution reaction (OER) catalysts are desirable for water splitting, but their development remains challenging due to poor accessibility of coordinatively unsaturated metal (cum) sites and low intrinsic activity. A large-area three-dimensional (3-D) macroporous interconnected nanosheet array of Ni-1,3,5-benzenetricarboxylate has been in situ self-assembled on Ti mesh (TM) by using ethanol as the solvent and high-affinity oxide layer on TM to promote in situ nucleation. The obtained nanoarchitecture exhibits much superior catalytic activity compared to most reported catalysts including MOF-based catalysts, other precious-metal-free ones, and Ir/Ru-based ones. Additionally, this electrode undergoes no current decay after 300 cyclic voltammetry (CV) cycles and can maintain at 250 mA cm^-2 for over 266 h. The excellent catalytic performance is mainly due to the 3-D macroporous and interconnected nanosheet array structure improving cum site exposure and charge transport and in situ activated cum cations enhancing OH^- adsorption. This work not only develops a facile and economical approach to synthesize 3-D macroporous interconnected MOF nanosheet arrays to simultaneously increase the number, exposure, and intrinsic activity of active sites and facilitate charge transport for high-performance eletrocatalysis, but provides scientific insights into the mechanisms for self-assembly of this unique nanoarchitecture and for the high OER performance.

Phase engineering of nickel-based sulfides toward robust sodium-ion batteries

Nickel-based sulfides are considered promising materials for sodium-ion batteries (SIBs) anodes due to their abundant resources and attractive theoretical capacity. However, their application is limited by slow diffusion kinetics and severe volume changes during cycling. Herein, we demonstrate a facile strategy for the synthesis of nitrogen-doped reduced graphene oxide (N-rGO) wrapped Ni₃S₂ nanocrystals composites (Ni₃S₂-N-rGO-700 °C) through the cubic NiS₂ precursor under high temperature (700 ℃). Benefitting from the variation in crystal phase structure and robust coupling effect between the Ni₃S₂ nanocrystals and N-rGO matrix, the Ni₃S₂-N-rGO-700 °C exhibits enhanced conductivity, fast ion diffusion kinetics and outstanding structural stability. As a result, the Ni₃S₂-N-rGO-700 °C delivers excellent rate capability (345.17 mAh g^-1 at a high current density of 5 A g^-1) and long-term cyclic stability over 400 cycles at 2 A g^-1 with a high reversible capacity of 377 mAh g^-1 when evaluated as anodes for SIBs. This study open a promising avenue to realize advanced metal sulfide materials with desirable electrochemical activity and stability for energy storage applications.

Electrochemical Detection of ompA Gene of C. sakazakii Based on Glucose-Oxidase-Mimicking Nanotags of Gold-Nanoparticles-Doped Copper Metal-organic Frameworks

The present work developed an electrochemical genosensor for the detection of virulence outer membrane protein A (ompA, tDNA) gene of Cronobacter sakazakii (C. sakazakii) by exploiting the excellent glucose-oxidase-mimicking activity of copper Metal-organic frameworks (Cu-MOF) doped with gold nanoparticle (AuNPs). The signal nanotags of signal probes (sDNA) that biofunctionalized AuNPs@Cu-MOF (sDNA-AuNPs@Cu-MOF) were designed using an Au-S bond. The biosensor was prepared by immobilization capture probes (cDNA) onto an electrodeposited AuNPs-modified glassy carbon electrode (GCE). AuNPs@Cu-MOF was introduced onto the surface of the GCE via a hybridization reaction between cDNA and tDNA, as well as tDNA and sDNA. Due to the enhanced oxidase-mimicking activity of AuNPs@Cu-MOF to glucose, the biosensor gave a linear range of 1.0 × 10^-15 to 1.0 × 10^-9 mol L^-1 to tDNA with a detection limit (LOD) of 0.42 fmol L^-1 under optimized conditions using differential pulse voltammetry measurement (DPV). It can be applied in the direct detection of ompA gene segments in total DNA extracts from C. sakazakii with a broad linear range of 5.4-5.4 × 10⁵ CFU mL^-1 and a LOD of 0.35 CFU mL^-1. The biosensor showed good selectivity, fabricating reproducibility and storage stability, and can be used for the detection of ompA gene segments in real samples with recovery between 87.5% and 107.3%.

Synthesizing nanoparticles of zinc and copper ferrites and examining their potential to remove various organic dyes through comparative studies of kinetics, isotherms, and thermodynamics

Nanoparticles of zinc ferrite (ZnFe₂O₄) and copper ferrite (CuFe₂O₄) were synthesized, and characterized, and these materials were applied for removal of organic dyes of alizarin yellow R (AYR), thiazole yellow G (TYG), Congo red (CR), and methyl orange (MO) from industrial wastewater through adsorption technique. Synthesis of ZnFe₂O₄ and CuFe₂O₄ was achieved through chemical co-precipitation method. These nanomaterials were characterized for physicochemical properties using XRD, FTIR, BET, VSM, DLS, Zeta-potential, and FESEM-EDX analytical instruments. BET surface areas of ZnFe₂O₄ and CuFe₂O₄ were 85.88 m²/g and 41.81 m²/g, respectively. Adsorption-influencing parameters including effect of solution pH, adsorbent quantity, initial concentration of dye pollutant, and contact time were examined. Acidic medium of the solution favored higher percentage of removal of dyes in wastewater. Out of different isotherms, Langmuir equilibrium isotherm showed the best fit with experimental data, indicating monolayer adsorption in the treatment process. The maximum monolayer adsorption capacities were found as 54.58, 37.01, 29.81, and 26.83 mg/g with ZnFe₂O₄, and 46.38, 30.06, 21.94, and 20.83 mg/g with CuFe₂O₄ for AYR, TYG, CR, and MO dyes, respectively. From kinetics analysis of the results, it was inferred that pseudo-second-order kinetics were fitting well with better values of coefficient of determination (R²). The removal of four organic dyes from wastewater through adsorption technique using nanoparticles of ZnFe₂O₄ and CuFe₂O₄ was observed to be spontaneous and exothermic. From this experimental investigation, it has been inferred that magnetically separable ZnFe₂O₄ and CuFe₂O₄ could be a viable option in removal of organic dyes from industrial wastewater.

Molten salt-confined pyrolysis towards heteroatom-doped porous carbon nanosheets for high-energy-density Zn-ion hybrid supercapacitors

Carbon nanosheets with heteroatom doping and well-developed porosity exhibit broad application foreground for Zn-ion hybrid supercapacitors (ZHSCs), but the simple and controllable preparation is still of great challenge. In this study, by using LiCl-KCl as in-built templates, histidine as carbon and nitrogen sources, and KNO₃, K₂SO₄, KOH or Na₂S₂O₃ as active agent, a series of N and NS doped porous carbon nanosheets are developed. Results indicate that, with the activator introduction, pore structures of the carbonized products are notably boosted, showing an astounding 30-244 % increase in BET specific surface area, and meanwhile, heteroatom with a content of ca. 12 % can be doped into the resultant carbon skeletons. Specifically, the NSPCN-800 (activated by Na₂S₂O₃) with a large specific surface area of 1297 m²/g, a hierarchically porous structure composed of abundant micropores and mesopores, and a suitable heteroatom content (N: 11.9 wt%; S: 0.6 wt%) presents an impressive energy storage behavior as cathode for ZHSCs, including a specific capacitance of 165.8F/g, a specific capacity of 95.2 mAh/g, an energy density of 59.0 Wh kg^-1 and a cyclic stability with a 82.6 % capacity retention after 5000 cycles. These performance parameters surpass numerous reported ZHSCs, making NSPCN-800 a very promising cathode for practical use.