Effective carbon capture and its facile conversion into high-value chemicals is reckoned as a practical solution to mitigating the impending climate change effects. Electrochemical conversion of CO2 to other compounds has emerged as one of the leading processes; however, it mostly lingers in the early stage of technology development with poor selectivity and high operational costs. Herein, we present a one-pot synthesis of a carbon-based bimetallic catalyst embedded in a carbon matrix derived from naturally abundant coconut fibers for the selective electrocatalytic reduction of CO2. Incorporating bismuth and nickel as active metals within an N-doped carbon matrix, the catalyst demonstrates an impressive faradaic efficiency of approximately 95% to produce CO while operating at -0.9 V vs. RHE. Further testing of the N-doped carbon supported Bi18Ni8O36 (Bi,Ni/N-C) composite catalyst in an electrolyzer revealed its capability to achieve a current density of 110 mA cm-2 required for industrial-level applications and can produce similar to 1.5 L (60.5 mmol) of CO in 6 hours. Density functional theory (DFT) calculations were conducted to gain deeper insights into the catalytic process, revealing that the nickel metal site exhibits greater activity in facilitating the CO2 reduction reaction (CO2RR). This approach not only enhances the selectivity and efficiency of CO2 conversion processes but also underscores the potential of utilizing cost-effective and biodegradable materials for catalyst design, offering a sustainable pathway to mitigate rising CO2 emissions and produce valuable industrial products.

Electrochemical CO2 reduction reaction (CO2RR), which is driven by electricity generated from renewable energy sources, is a promising technology for sustainably producing carbon-based chemicals or fuels. Several CO2RR catalysts have been explored to date, among which copper-based electrocatalysts are the most widely known for electrochemical CO2RR and are extensively studied for their ability to generate an array of products. Their low selectivity, however, hinders their possibility of being used for practical purposes. In this work, a microwave-assisted one-pot synthesized CuxO/N-doped carbon demonstrates the electrochemical conversion of carbon dioxide into multiple C-1 products (mainly formate and methanol), with a maximum Faradaic efficiency of 95% in 0.10 m KHCO3 aqueous solution at a moderately low applied potential of -0.55 V versus RHE (reversible hydrogen electrode). The in-depth theoretical study reveals the key contribution of pyridinic N-based N-doped carbon sites and Cu2O clusters in CO2 adsorption and its subsequent conversion to formate and methanol via an energetically favorable formate pathway. The electrocatalyst continued to demonstrate CO2 reduction to valuable C-1 products when a simulated flue gas stream containing 15% CO2 along with 500 ppm SOx and 200 ppm NOx is used as an inlet feed.

Glycerol, a significant byproduct of biodiesel manufacturing, offers the potential for conversion into valuable substances such as formic acid (FA), glyceric acid (GLA), and glycolic acid (GCA). The selective oxidation of glycerol, especially into FA, is both economically crucial and technically challenging. While precious metals like gold (Au) and platinum (Pt) have conventionally served as catalysts, there is growing interest in nonprecious alternatives. In this context, we explored the use of complex metal oxide, cerium vanadate nanosheets (CeVO4 NS), as a catalyst for the electrochemical oxidation of glycerol to FA. The higher surface area (compared to the 3D structure) coupled with the redox-active nature and electric properties of CeVO4 NS facilitate the electrocatalytic performance. The glycerol oxidation with the CeVO4 NS electrocatalyst exhibited a highly selective formation of FA with a high Faradaic efficiency of 91.5%. The reaction is also kinetically more facile than competing reactions, and the performance is better than the reported catalysts. The mechanistic investigation revealed that the formation of FA involves GCA as an intermediate. Alternately, selective and efficient sensing of hydrogen peroxide (H2O2) is of paramount importance in industries for environmental monitoring and clinical uses. Owing to its beneficial structural and electronic features, the CeVO4 NS were also employed for electrochemical nonenzymatic H2O2 sensing. The CeVO4 NS exhibited high sensitivity (175 mu A mM(-1)cm(-1)) toward electrochemical H2O2 sensing with a detection limit of 5.6 mu M. Importantly, the CeVO4 NS sensor system is reusable and stable. The superior glycerol oxidation and H2O2 sensing performance establish the enormous potential of CeVO4 NS as a multifunctional material.

The sluggishness of the complementary oxygen evolution reaction (OER) is reckoned as one of the major drawbacks in developing an energy-efficient green hydrogen-producing electrolyzer. An array of organic molecule oxidation reactions, operational at a relatively low potential, have been explored as a substitute for the OER. Glycerol oxidation reaction (GOR) has emerged as a leading alternative in this context because glycerol, a waste of biodiesel manufacturing, has become ubiquitous and accessible due to the significant growth in the biodiesel sector in recent decades. Additionally, the GOR generates several value-added organic compounds following oxidation that enhance the cost viability of the overall electrolysis reaction. In this study, a low-cost, room temperature operable, and energy-efficient synthetic methodology has been developed to generate unique two-dimensional CuO nanosheets (CuO NS). This CuO NS material was embedded on a carbon paper electrode, which showcased excellent glycerol electro-oxidation performance operational at a moderately low applied potential. Formic acid is the major product of this CuO NS-driven GOR (Faradaic efficiency ~80 %), as it is formed primarily via the glyceraldehyde oxidation pathway. This CuO NS material was also active for oxidizing other abundant alcohols like ethylene glycol and diethylene glycol, albeit at a relatively poor efficiency. Therefore, this robust CuO NS material has displayed the potential to be used in large-scale electrolyzers functioning with HER/GOR reactions.

The H2-mediated energy transduction strategy emerged as one of the best options in our journey toward a carbon-neutral energy infrastructure where the water-splitting reaction remains a key component. Oxygen evolution reaction (OER) is one of the principal segments of water electrolysis as well as hydrogen production. However, the OER is a slow reaction in nature and demands the intervention of a catalyst to drive it at a commendable rate and efficiency, ensuring its practical application. In recent years, phosphide-based materials have emerged as unique electrocatalysts triggering oxygen evolution from water. In this Review, the potential role of transition metal phosphides (TMPs) as the anodic material in electrocatalytic water splitting has been depicted in detail. The remarkable reactivity of bimetallic nickel-iron phosphide (NiFeP), which deploys multiple redox sites leading to electrochemical bidirectionality and extensive stability, is highlighted. We have also outlined the rationale for heterostructure design with varying elemental combinations and nanocomposite morphologies to upgrade the OER activity. Furthermore, we have also highlighted upcoming challenges lying ahead of these materials before they can be inducted as next-generation catalytic materials for large-scale applications.

In recent years, the synthesis of materials in lower dimensions, like two-dimensional (2D) or ultrathin crystals, with distinctive characteristics has attracted substantial scientific attention. The mixed transition metal oxides (MTMOs) nanoma-terials are the promising group of materials, which have been extensively utilized for various potential applications. Most of the MTMOs were explored as three-dimensional (3D) nanospheres, nanoparticles, one-dimensional (1D) nanorods, and nanotubes. However, these materials are not well explored in 2D morphology because of the difficulties in removing tightly woven thin oxide layers or exfoliations of 2D oxide layers, which hinder the exfoliation of beneficial features of MTMO. Here, through the exfoliation via Li+ ion intercalation and subsequent oxidation of CeVS3 under hydrothermal condition, we have demonstrated a novel synthetic route for the fabrication of 2D ultrathin CeVO4 NS. The as-synthesized CeVO4 NS exhibit adequate stability and activity in a harsh reaction environment, which gives excellent peroxidase-mimicking activity with a KM value of 0.04 mM, noticeably better than natural peroxidase and previously reported CeVO4 nanoparticles. We have also used this enzyme mimic activity for the efficient detection of biomolecules like glutathione with a LOD of 53 nM.

The development of transition metal oxide nano/microstructures with inherent enzyme-mimicking activity has attracted immense research interest owing to the advantages they offer over natural enzymes. In this work, CuxO-ZnO microstructures have been utilized to mimic two important enzymes, laccase, and peroxidase. CuxO-ZnO microstructures with a star-shaped morphology have been synthesized using polyethylene glycol 200 (PEG 200) as a solvent and shape-directing agent. The CuxO-ZnO microstructures exhibited excellent laccase- and peroxidase-mimicking activities even at harsh conditions, such as elevated temperatures, ionic strength, and varying pH. The laccase-like activity of the nanozyme has been utilized for the colorimetric detection of epinephrine with a detection limit of 0.09 µM. Using the peroxidase-like activity, glutathione and gallic acid have been detected with a limit of detection of 1.35 and 0.15 µM, respectively. The use of such hybrid structures as nanozymes will open up newer avenues for their use in biosensing as well as environmental remediation.

The development of earth-abundant metal-oxide based nanomaterials with an intrinsic enzyme-mimicking activity (nanozyme) is useful for both practical applications and fundamental research. The laccase enzyme is a multicopper oxidase that finds commercial utility in environmental remediation and biotechnology, but with significant limitations under harsh conditions. Herein, we present the laccase-like activity of Cu2O nanospheres, fabricated using a one-pot polyol-based microwave assisted method. The as-synthesized Cu2O nanospheres possess great stability under harsh conditions and exhibit excellent laccase-like activity with a K-M value of 0.2 mM, considerably smaller than those of previously reported nanozymes as well as native laccase. The utility of the nanozyme was demonstrated in the efficient oxidation of phenolic pollutants under real-life high-salinity conditions, as well as in the colorimetric detection of biomolecules such as epinephrine and dopamine with sensitivities of 10 and 6.5 mu M, respectively. Notably, the Cu2O nanozyme enabled naked-eye detection of the acetylcholinesterase enzyme with a biorelevant sensitivity (2.5 pM). This robust and recyclable laccase-mimicking nanozyme introduces a simple and cost-effective metal oxide platform that would find multiple practical applications in environmental remediation, catalysis, and biosensing.

The cover image shows the formation mechanism of misfit calcium cobalt oxide nanotubes, part of Prof. Leela S. Panchakarla's work from when he was a post-doc at the Weizmann Institute under Prof. Reshef Tenne. Prof. Panchakarla, a gifted materials chemist, contributed significantly to the field of layered materials. This special issue is dedicated to the memory of Prof. Leela S. Panchakarla, who passed away shortly after submitting his article to the Israel Journal of Chemistry (https://doi.org/10.1002/ijch.202100080).

The liquid-liquid interface (LLI) technique has been used to form thin films of various materials parallel to the interface. In this report, by taking CuS as an example, we show that CuS not only adopts thin film structures at the liquid-liquid interface parallel to the interface but can also utilize beyond the interface to form self-supported vertically aligned CuS thin films by controlling the precursor concentration. We also report the formation of a self-assembled monolayer of CuS nanoparticles in the dichlorobenzene-water interface at a lower concentration of copper. Thin films generated at LLI show p-type conductivity with a sheet resistance of similar to 350 omega/ and transparency up to 72 % at 550 nm. CuS also show electrocatalytic activity towards glucose sensing with a sensitivity of 3958 mu A mM(-1) cm(-2), which is among the best in copper-based materials.

The development of functional oxide nanostructures with a controlled size and morphology is crucial for fine-tuning of the properties and their applications in diverse areas. Herein, a simple and facile, template-free synthetic approach has been adopted for the fabrication of hybrid ZnO-CuxO nanostructures with a flower-like morphology through a hydrothermal pathway using a polyethylene glycol-water mixture as a reaction medium in a single step. The ZnO-CuxO nanoflowers thus obtained were characterized using a variety of spectroscopic and electron microscopic techniques. The formation of flower-like superstructures with diameters in the range of 8-10 mu m could be confirmed from the electron microscopic studies. A detailed analysis indicates the critical role of metal counterions as well as the amount of water in the reaction medium during the shape-controlled evolution of the flower-like structures. The nanoflowers could be successfully utilized for the electrochemical detection of p-nitrophenol as well as H2O2. The limits of detection for p-nitrophenol and H2O2 were calculated to be 15.7 and 7.3 mu M, respectively. The excellent detection ability can be attributed to the synergistic effect between ZnO and CuxO in the hybrid composite. The template-free synthesis of ZnO-CuxO nanostructures might provide a simple method for the development of other mixed oxide nanostructures with application potential in sensing of environmental hazards.

Strategically doped metal oxide nanomaterials signify a rapidly growing genre of functional materials with a wide range of practical applications. Copper vanadate (CuV) represents one such highly active system, which has been rarely explored following its doping with an abundant first-row transition metal. Here, we have developed a series of CuV samples with varying cobalt(ii) doping concentrations deploying a relatively simple solid state synthetic procedure. Among the samples, the 10% Co(ii)-doped CuV (Co10%-CuV) exhibited excellent reactivity for both the H2 evolution reaction (HER) and glycerol oxidation reaction (GOR) in an alkaline aqueous medium (pH 14.0) during cathodic and anodic scans, respectively. During this dual-active catalysis, surface-immobilized Co10%-CuV operates at exceptionally low overpotentials of 176 mV and 160 mV for the HER and GOR, respectively, while achieving 10 mA cm2 current density. The detailed spectroscopic analysis revealed the formation of formate as the major product during the GOR with a faradaic efficiency of >90%. Therefore, this Co10%-CuV can be included on either side of a two-electrode electrolyzer assembly to trigger a complete biomass-driven H2 production, establishing an ideal carbon-neutral energy harvest process.

Catalyst-free photoinduced processes in aqueous medium represent significant advancement toward development of green and sustainable pathways in organic synthesis. tert-Butyl hydroperoxide (TBHP) is a widely used oxidant in organic reactions, where the decomposition of TBHP into its radicals by metal catalysts or other reagents is a key factor for efficient catalytic outcome. Herein, we report a simple and environmentally friendly visible light-promoted synthetic pathway for the synthesis of N-heterocyclic moieties, such as quinazolinones and quinoxalines, in the presence of TBHP as an oxidizing agent in aqueous medium that requires no catalysts/photocatalysts. The enhanced rate of decomposition to generate free radicals from TBHP upon visible light irradiation is the driving force for the domino reaction.

The increase in the use of bactericides is a matter of grave concern and a serious threat to human health. The present situation demands rapid and efficient detection and elimination of antibiotic-resistant microbes. Herein, we report the synthesis of a simple C3-symmetric molecular system (TGP) with an intrinsic positive charge through a single-step Schiff base condensation. In a water-dimethyl sulfoxide (DMSO) solvent mixture (80:20 v/v), TGP molecules self-aggregate to form spherical nanoparticles with a positively charged surface that displays efficient fluorescence owing to the aggregation-induced emission (AIE) phenomenon. Both Gram-positive and Gram-negative bacteria could be effectively detected through "turn-off" fluorescence spectroscopy as the electrostatic interaction of the resultant nanoaggregates with the negatively charged bacterial surface induced quenching of fluorescence of the nanoparticles. The fluorescence analysis and steady-state lifetime studies of TGP nanoparticles suggest that a nonradiative decay through photoinduced electron transfer from the nanoparticles to the bacterial surface leads to effective fluorescence quenching. Further, the TGP nanoaggregates demonstrate potent antimicrobial activity against microbes such as multidrug-resistant bacteria and fungi at a concentration as low as 74 μg/mL. A combination of factors including ionic surface characteristics of the nanoparticles for strong electrostatic binding on the bacterial surface followed by possible photoinduced electron transfer from the nanoaggregates to the bacterial membrane and enhanced oxidative stress in the membrane resulting from reactive oxygen species (ROS) generation is found accountable for the high antimicrobial activity of the TGP nanoparticles. The effective disruption of membrane integrity in both Gram-positive and Gram-negative bacteria upon interaction with the nanoaggregates can be observed from field emission scanning electron microscopy (FESEM) studies. The development of simple pathways for the molecular design of multifunctional broad-spectrum antimicrobial systems for rapid and real-time detection, wash-free imaging, and eradication of drug-resistant microbes might be crucial to combat pathogenic agents.

Development of nanozymes with intrinsic multienzyme mimetic activity has attracted tremendous research attention as nanozymes offer several advantages over multimodal natural enzymes and are a key toward multifunctional biomedical applications. Shape-selective ternary metal oxides with multicatalytic sites can be developed as potential multienzyme mimetic nanomaterials taking advantage of the variable valence states of the metal constituents and their synergy along with the added advantage offered by the exposed surface for enhanced catalytic activity. Herein, we have explored the multicatalytic activity of Cu3V2O7(OH)(2)center dot 2H(2)O nanoribbons for peroxidase, oxidase, and laccase mimicking activity. The fabrication of Cu3V2O7(OH)(2) nanoribbons was performed using the polyol-based hydrothermal pathway, and the choice of precursor metal salts and their molar ratio was found to be instrumental in the shape, size, and phase selective evolution of copper pyrovanadates. The as-synthesized nanoribbons showed excellent peroxidase-like activity with K-m value of 0.004 mM for H2O, which is considerably smaller than those reported for HRP and other nanozymes. The efficient oxidase mimicking behavior of these Cu3V2O7(OH)(2) nanoribbons could be used for the colorimetric detection of glutathione with a limit of detection of 0.08 mu M. Further, the nanoribbons also showed laccase-mimetic behavior and were used for the colorimetric detection of epinephrine, which is a useful hormone and neurotransmitter.

Development of nanozymes, which are nanomaterials with intrinsic enzymatic properties, has emerged as an appealing alternative to the natural enzymes with tremendous application potential from the chemical industry to biomedicine. The self-assembled growth of micrometer-sized oxide materials with controlled nonspherical shapes can be an important tool for enhancing activity as artificial enzymes, as the formation of these superstructures often results in high surface area with favorable impact on catalytic activity. Herein, the growth of rod-shaped Fe3O4 microstructures via a one-pot microwave-based method and using a water-poly(ethylene glycol) mixture as a solvent is reported, without the involvement of external shape-directing agents. The precursor metal salt played a key role in the size, shape, and phase selective evolution of iron oxide micro/nanomaterials. Whereas self-assembled microrod superstructures were obtained using Fe(NO3)3 as the metal salt precursor, use of FeCl3 or Fe-acetate as precursors afforded hollow Fe2O3 microparticles and Fe3O4 nanoparticles, respectively. A graphitic layer was deposited on the Fe3O4 surface, imparting a negative surface charge as a result of a high-temperature treatment of poly(ethylene glycol). The rod-shaped Fe3O4 microcrystals show efficient peroxidase-mimicking activity toward 3,3,5,5'-tetramethylbenzidine and pyrogallol as peroxidase substrates with a Michaelis-Menten rate constant (Km) value of 0.05 and 0.52 mM, respectively. The proficient enzyme mimicking behavior of these magnetic superstructures was further explored for the degradation of organic dyes that includes rhodamine B, methylene blue, and methyl orange with a rate constant (k) of 0.038, 0.011, and 0.007 min-1 respectively, using H2O2. This fast and simple method could help to develop a new pathway for differently shaped oxide nanoparticles in a sustainable and economical manner that can be harnessed as nanozymes for industrial as well as biological applications.

The ultimate aim in developing controlled drug delivery systems is to derive formulations to achieve drug release at a constant rate over a long duration. The drug release profile that follows zero-order kinetics is crucial for reduction in the drug administration frequency, reduced cytotoxicity, and improved convenience and compliance of patients. Designed drug delivery systems for achieving zero-order release are often complex, expensive, and difficult to manufacture. Herein, we demonstrate that a supramolecular hydrogel formed through the self-assembly of guanosine monophosphate (GMP) into highly ordered G-quadruplex structure and cross-linked through Fe3+ and Ca2+ ions exhibits potential for the pH-responsive controlled zero-order drug release of doxorubicin, a model chemotherapeutic drug. The fibril formation is initiated by the self-assembly of GMP into a quadruplex complex, which is cross-linked through the complexation of the phosphate groups with Fe(III) ions, resulting in a spontaneous hydrogel formation. The Ca2+ ions facilitate the improvement in the mechanical integrity of the fibril network in the Fe-GMP hydrogel via cross-linking of sugar moieties. The hydrogel showed a high loading capacity for drug molecules and a pH-responsive sustained zero-order drug release over several days owing to the lowered degradability of the cross-linked hydrogel in acidic buffer stimulant. In vitro drug-release studies further established a controlled pH-triggered drug release profile. The Ca2+ cross-linking of the Fe-GMP hydrogel also resulted in significant enhancement in the biocompatibility of the drug delivery system. The fabrication of biocompatible, low-cost, and efficient Ca2+ cross-linked metal-organic hydrogels may present promising applications in biological fields.

The development of synthetic protocols for biologically important molecules using biocompatible catalysts in aqueous medium holds the key in green and sustainable chemistry. Herein, a magnetically recoverable iron oxidecarbon dot nanocomposite has been demonstrated as an effective catalyst for cyclooxidative tandem synthesis of quinazolinones in aqueous medium using alcohols as starting materials. Fluorescent carbon dots, the newest entrant in the nanocarbon family, were used as the stabilizing agent for the iron oxide nanoparticles, and a continuous layer of carbon dots decorates the iron oxide nanoparticle surface as observed by transmission electron microscopy. The fluorescence studies demonstrated the effective electron transfer from carbon dots to the iron oxide nanoparticles resulting in complete quenching of emission owing to carbon dots, once it binds with iron oxide nanoparticles. The nanocatalyst showed high activity with significant reusability for the syntheses of quinazolinones in the presence of tert-butyl hydroperoxide (TBHP) in an aqueous medium. Controlled experiments revealed the synergistic effect of carbon dots in enhancing the catalytic activity of iron oxide, as they might influence the decomposition of TBHP into radicals owing to their peroxidase activity. These radicals stabilized over the nanoparticle surface are known to have increased lifetime compared to solution-based radicals. These surface-stabilized radicals then could catalyze the tandem reaction resulting in the formation of the quinazolinone derivatives in high yields.

Development of solution based synthetic methodology for the controlled growth of hyperbranched oxide nanomaterials is important for practical applications in nanotechnology. A binary metal oxide nanocomposite CuxO-ZnO with octapod microstructures was fabricated in a one pot hydrothermal method using a water-polyethylene glycol mixture as a solvent. The highly oriented growth of the microstructures emerged from controlled mixing of the precursor metal salts without any involvement of external shape-directing agents. An investigation into the organized conformation and geometric architectural evolution revealed that the reaction temperature and concentration ratio of the precursor metal salts played critical roles on the morphology of the composite structure. The obtained octapod architecture was characterized by various spectroscopic as well as microscopic techniques. A time dependent study demonstrated the evolution of octapod morphology from self-assembled cubic seeds in a template-free pathway. The hyperbranched mixed metal oxide composite showed effective catalytic activity for the reduction of 4-nitrophenol with a rate constant (k(app)) of 2.1 x 10(-2) s(-1) and an activity factor (K) of 2100 s(-1) g(-1). Additionally, the composite oxide material showed high efficiency toward the reduction of common organic dye pollutants under ambient condition. Moreover, the CuxO-ZnO octapodal microcrystals showed excellent activity toward electrocatalytic glucose oxidation with a sensitivity of 2091 mu A/mmol/cm(2) when a potential of 0.6 V was applied. The high efficiency of the microparticles in these catalytic applications could be attributed to the coexistance of CuxO and ZnO phases in the matrix and the synergistic electronic effect owing to the formation of heterojunctions, which allowed efficient movement of holes and free electrons. The template-free structural evolution of the CuxO-ZnO materials into octapodal geometry through a simple hydrothermal pathway might encourage promising applications for sensing and organic decontamination.