Search

In this study, a novel aptasensor based on a transition metal oxide–modified pencil graphite electrode (PGE) was developed for the diagnosis of early-stage prostate cancer (PCa) via monitoring the prostate-specific antigen (PSA), which is the main biomarker for PCa. Single-use PGEs modified with pulsed deposited manganese oxide (MnOx) film were used to attach the amino-terminated aptamer specific to the PSA via carbodiimide chemistry. The designed aptasensor was placed in an electrochemical cell containing ferri/ferrocyanide ions as a redox probe to measure the charge transfer resistances (Rct) of the electrode surface by electrochemical impedance spectroscopy (EIS) to follow the response of each modification step. The effect of the medium pH on the ionic structure of the aptamer molecule according to its pI value and, thus, the reversing of the direction of the response (ΔRct) by the pH change was also discussed. The level of PSA secreted from PCa cells was investigated using impedimetric transduction. The specificity of the aptasensor was validated through selectivity studies against non-specific tumor markers like VEGF and different cancer cell lines including breast cancer and androgen-insensitive prostate cancer. The developed system showcases a label-free, fast, specific, and cost-effective approach for PSA detection, highlighting the importance of medium pH and the electrostatic environment on the aptamer's response. Our work emphasizes the potential for such aptasensors in clinical diagnostics and paves the way for further exploration into using transition metal oxides in biosensing applications. [ABSTRACT FROM AUTHOR]

In order to develop advanced energy storage devices, it is necessary to manufacture supercapacitor electrode that have both long electrochemical cycle lifetimes and high energy densities. These properties can only be obtained by developing heterostructure pseudo-capacitive materials. The combination of MnO 2 nanorods and ZnCr 2 O 4 nanoparticles resulted in a synergistic effect, which increased the electroactive surface area for charge storage. This effect was not observed when each component utilized individually. The material ZnCr 2 O 4 nanoparticles facilitated the MnO 2 nanorods. In present study, ZnCr 2 O 4 , MnO 2 and their composite was fabricated by simple sonication process. These fabricated samples were tested by using different techniques which includes X-ray diffraction (XRD), Raman analysis, Brunauer Emmett Teller (BET) and scanning electron microscopy (SEM). Electrochemical analysis of fabricated materials exhibited an exceptional specific capacitance (C sp = 1175.35 F g−1), energy density (E d = 15.95 Wh Kg−1) and power density (P d = 869.4 W kg−1). These materials are anticipated to act as the support for electrochemical energy storage devices that utilize an ideal electrode structure, meticulously select the appropriate transition metal oxide (TMO) and analyse electrochemical characteristics for supercapacitive performance. This study exhibits the remarkable efficiency of the nanostructured ZnCr 2 O 4 /MnO 2 electrode in supercapacitors with high energy density (E d). [ABSTRACT FROM AUTHOR]

Biomass derived carbon is considered as a promising carbon because it contains abundant channel and pore structure and is not easy to degrade. Double transition metal oxides show abundant valence states, good biocompatibility, conductivity, high stability and satisfactory catalytic properties. In addition, a large number of waste biomass such as the fruit peel could cause the waste of resources and environmental pollution. Therefore, we used waste grape skins as a carbon source for assembly with double transition metal oxides. After calcination at high temperature, N-doped biomass-derived carbon loaded with double transition metal oxide composite was formed. The waste grape skins carbon substrate with large pores and large specific surface area provides more channels for ion migration and electron transport, promotes charge transfer, and further improves the ability to reduce NB. The material shows excellent electro-catalytic activity for nitrobenzene (NB), the limit of detection (LOD) is as low as 0.143 μM, the linear response range is wide (0.47–1798.71 μM), the sensitivity is high, the reproducibility, the selectivity and the stability are good. In addition, the sensing assembled from this material has achieved a recovery rate of 97–102.6 % in testing the NB content in actual water sample. This work provides a new idea for the detection of NB, and also finds a greener and more meaningful treatment method for waste biomass. [ABSTRACT FROM AUTHOR]

This work comprises a generalization of a simple geometric model originally developed to describe coupled rotations of corner-sharing octahedra in the surface layer of S r 2 RuO4 under uniaxial compression. The main objective of the model is to establish a link between the experimental global strain configuration and the possible microscopic mechanisms and compatible geometries by which the octahedra accommodate the applied strain. In achieving this, a useful and intuitive parametrization of four-site two-dimensional systems of corner-sharing octahedra has been established, which can be readily extended to three dimensions and N > 4 inequivalent sites or directly employed to analyze the octahedral configuration of many perovskites, transition metal oxides (TMOs), and layered compounds. [ABSTRACT FROM AUTHOR]

Electronic configuration regulation is usually a feasible strategy to boost the electrocatalytic performance for transition metal oxides. Herein, a simple high-temperature annealing method is employed to optimize the electrocatalytic activity towards hydrogen evolution reaction (HER) for spinel oxide Co 3 O 4. The experimental results indicate the simple thermal treatment partially drives the structure reversal in spinel Co 3 O 4 , and it induces the redistribution of cobalt ions at tetrahedral and octahedral sites. Thereby, the electronic configuration regulation occurs, and the e g occupation of cobalt ions at octahedral sites increases up to 1, optimizing the HER reaction kinetics. The sample treated at 900 °C exhibits the highest activity, with overpotential of 335 mV at current density of 10 mA cm−2, and Tafel slope value of 99.3 mV dec−1. This work offers a new way of tuning the electronic configuration in spinel oxides to boost HER electrocatalytic activity. • A simple high-temperature annealing method was adopted to partially drive the structure reversal in Co 3 O 4. • Partial structure reversal can induce redistribution of cobalt ions, and effectively modulate electronic configuration. • Complex spinel exhibited better HER activity than that of normal spinel. [ABSTRACT FROM AUTHOR]

The emergence of new functionalities in transition metal oxides and their interfaces poses an important challenge. Many recent discoveries regarding the polar/nonpolar interface between perovskite oxides open new avenues for modern applications. SrTiO3/LaCrO3 heterostructures are particularly intriguing due to a polar discontinuity along the [001] direction, giving rise to two distinct and controllable interface structures, TiO2-LaO and SrO-CrO2, which exhibit new and promising electronic and thermoelectric transport properties. Through a combination of first-principles simulations based on density functional theory and the Boltzmann transport equation, we have calculate and discuss the structural, electronic, valence band offset, and thermoelectric properties of SrTiO3, LaCrO3, and SrTiO3/LaCrO3 heterostructures. The temperature dependence of the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, and figure of merit is determined. Furthermore, we highlight the effect of the interface between the polar perovskite LaCrO3 and the nonpolar SrTiO3(001) on the thermoelectric properties, wherein we observed a change in the metal–semiconductor transport behavior. These results constitute an important advancement in our understanding of the thermoelectric properties at polar/nonpolar perovskite oxide interfaces. [ABSTRACT FROM AUTHOR]

NiO and ZnO mixed nanocomposites were manufactured using the solution combustion process. As-prepared samples were analyzed using XRD. The XRD shows an average crystallite size of 35–40 nm. The elemental composition determined by EDS indicates a nearly equal proportion of Ni and Zn, with an atomic ratio of Ni/Zn = 0.96. The specific capacitances of NiO is 295.5 Fg-1, ZnO is 117.3 Fg-1 and ZnO/NiO nanocomposites is 561.75 Fg-1 which are more than NiO and ZnO alone. This study shows that constructing binary oxide nanocomposites is an approach for developing high-performance supercapacitor electrode materials. Experimental observations on catalytic activity revealed that NiO/ZnO increased catalytic activity. Furthermore, adding NiO to ZnO in the composite increased the overall amount of oxygen vacancies in the samples. Our research lays the door for a simple, inexpensive, nontoxic, and quick technique to synthesize binary transition metal oxide-based electrode materials for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Copper oxide (CuO) is an important transition metal oxide used in a wide variety of applications, such as gas sensors, magnetic storage media, lithium-ion electrodes, electronic device fabrication etc. CuO nanostructures (NS) exhibit exclusive properties considerably different from their bulk counterparts, such as highly reactive surfaces, different optical, electrical and catalytic properties which strongly depend on the shape, size and crystal structure of the NS. By altering the aspect ratio (length to diameter ratio) and shape of CuO NS, physical and chemical properties of these NS can be tailored. In this work, an array of CuO NS was synthesized on thin copper foil substrate through wet chemical route at different temperatures and times, followed by a thermal reduction in an Ar/H2 atmosphere. Cu foil itself was polished to different roughness levels and deformed to different thickness levels, prior to the reaction, to induce different growth conditions leading to the formation of CuO NS of different morphologies. The present study shows simple, scalable technique to synthesize various CuO NS that can be helpful in future to ameliorate various physical and chemical properties of CuO. [ABSTRACT FROM AUTHOR]

Spin texture in k -space is a consequence of spin splitting due to strong spin–orbit coupling and inversion symmetry breaking. It underlies fertile spin transport phenomena and is of crucial importance for spintronics. Here, we observe the spin texture in k -space of nominally centrosymmetric SrIrO3 grown on NdGaO3 (110) substrates, using non-linear magnetotransport measurements. We demonstrate that the spin texture is not only induced by the interface, which inherently breaks the inversion symmetry in strong spin–orbit coupled SrIrO3 films, but also originates from the film bulk. Structural analysis reveals that thicker SrIrO3 films exhibit a strain gradient, which could be considered as a continuous change in the lattice constant across different layers and breaks the inversion symmetry throughout the entire SrIrO3 films, giving rise to the spin texture in k -space. First-principles calculations reveal that the strain gradient creates large spin-splitting bands, inducing the spin texture with anisotropy, which is consistent with our experimental observations. Our results offer an efficient method for inducing the spin textures in k -space. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA)-based materials are utilized as a bioactive ceramic for musculoskeletal reconstruction, owing to their chemical similarities to bone. However, they do not have any inherent antibacterial properties. Hence, post-surgical bacterial infection on HA scaffolds may cause osteomyelitis that needs to be rectified with costlier and more painful revision surgery. Our research aims to dope HA with transition metal oxides, such as ZnO and MgO, followed by loading tannic acid (TA) as an alternate antibacterial agent for various orthopedic and dental applications. The phase and microstructural investigation studies show no adverse effect as a result of doping. The combined effects of dopants and TA lead to ~ 98% antibacterial efficacy against S. aureus after 24 h of sample–bacterial interactions. The selected compositions do not show any adverse effects on the NIH3T3 cell line. In summary, our work proposes an alternate strategy to fabricate an antibacterial scaffold with TA-loaded ZnO and MgO-doped HA for various orthopedic and dental applications. [ABSTRACT FROM AUTHOR]

Ceramic proton conductors have the potential to lower the operating temperature of solid oxide cells (SOCs) to the intermediate temperature range of 400–600 °C. This is attributed to their superior ionic conductivity compared to oxide ion conductors under these conditions. However, prominent proton-conducting materials, such as yttrium-doped barium cerates and zirconates with specified compositions like BaCe1−xYxO3−δ (BCY), BaZr1−xYxO3−δ (BZY), and Ba(Ce,Zr)1−yYyO3−δ (BCZY), face significant challenges in achieving dense electrolyte membranes. It is suggested that the incorporation of transition and alkali metal oxides as sintering additives can induce liquid phase sintering (LPS), offering an efficient method to facilitate the densification of these proton-conducting ceramics. However, current research underscores that incorporating these sintering additives may lead to adverse secondary effects on the ionic transport properties of these materials since the concentration and mobility of protonic defects in a perovskite are highly sensitive to symmetry change. Such a drop in ionic conductivity, specifically proton transference, can adversely affect the overall performance of cells. The extent of variation in the proton conductivity of the perovskite BCZY depends on the type and concentration of the sintering aid, the nature of the sintering aid precursors used, the incorporation technique, and the sintering profile. This review provides a synopsis of various potential sintering techniques, explores the influence of diverse sintering additives, and evaluates their effects on the densification, ionic transport, and electrochemical properties of BCZY. We also report the performance of most of these combinations in an actual test environment (fuel cell or electrolysis mode) and comparison with BCZY. [ABSTRACT FROM AUTHOR]

Electrochromic (EC) films are widely used in smart windows, automobile mirrors, and low-power displays due to their capability of reversibly changing color under an external potential. Transition metal oxides, due to their ability to switch between multiple oxidation states, are primarily used as EC films. They require low operating power and provide high coloration efficiency in EC applications. However, their thin-film fabrication through a low-cost and scalable process is still challenging. Here, nickel oxide (NiO) EC films have been synthesized by room-temperature electrochemical oxidation of Ni thin films. The Ni films were grown by electroless deposition and annealed at three different temperatures of 100°C, 200°C, and 300°C. The morphological, optoelectronic, and electrochemical properties of the films have been comparatively analyzed to obtain an optimized EC film. The NiO film annealed at 100°C exhibited superior properties with coloration and bleaching times of 1.8 s and 2.9 s, respectively, and a coloration efficiency of 20 cm2/C. This annealed film is further used to fabricate a EC device with NiO and tungsten oxide (WO3) as the electrode layers and a phosphoric acid-based gel as the electrolyte. The low-temperature deposition process used here can also be extended to flexible substrates. [ABSTRACT FROM AUTHOR]

Transition metal oxide magnetite (Fe3O4) is recognized as a potential anode material for lithium-ion batteries owing to its high theoretical specific capacity, modest voltage output, and eco-friendly character. It is a challenging task to engineer high-performance composite materials by effectively dispersing Fe3O4 crystals with limited sizes in a well-designed supporting framework following sustainable approaches. In this work, the naturally abundant plant products sodium lignosulfonate (Lig) and sodium cellulose (CMC) were selected to coprecipitate with Fe3+ ions under mild hydrothermal conditions. The Fe-Lig/CMC intermediate sediment with an optimized microstructure can be directly converted to the Lig/CMC-derived carbon matrix-supported Fe3O4 nanocomposite sample (Fe3O4@LigC/CC). Compared with the controlled Fe3O4@LigC material, the Fe3O4@LigC/CC nanocomposite provides superior electrochemical performance in the anode, which has inspiring specific capacities of 820.6 mAh g−1 after 100 cycles under a current rate of 100 mA·g−1 and 750.5 mAh g−1 after 250 cycles, as well as more exciting rate capabilities. The biomimetic sample design and synthesis protocol closely follow the criteria of green chemistry and can be further developed in wider scenarios. [ABSTRACT FROM AUTHOR]

Lithium-titanium-sulfur cathodes have garnered interest due to their distinctive properties and potential applications in lithium-ion batteries. They present various benefits, including lower cost, enhanced safety, and greater energy density compared to the commonly used transition metal oxides. The current trend in lithium-ion batteries is to move to all-solid-state chemistries in order to improve safety and energy density. Several chemistries for solid electrolytes have been studied, tested, and characterized to evaluate the applicability in energy storage system. Among those, sulfur-based Argyrodites have been coupled with cubic rock-salt type Li2TiS3 electrodes. In this work, Li2TiS3 surfaces were investigated with DFT methods in different conditions, covering the possible configurations that can occur during the cathode usage: pristine, delithiated, and overlithiated. Interfaces were built by coupling selected Li2TiS3 surfaces with the most stable Argyrodite surface, as derived from a previous study, allowing us to understand the (electro)chemical compatibility between these two sulfur-based materials. [ABSTRACT FROM AUTHOR]

Herein, La@MxOy/TiO2 (M = V, Cr, Mn and Fe) composite catalysts were prepared based on the sol–gel method as an effective adsorbent and photocatalyst for the degradation of malachite green from an aqueous solution under UV–Vis light. Under experimental conditions, a maximum adsorption capacity of 57.10% for the malachite green dye was achieved with La@Fe2O3/TiO2. Moreover, this composite showed 78.62% photodegradation efficiency for malachite green. A quadratic model constructed using the response surface method showed that the maximum efficiency of photodegradation of malachite green can be achieved at pH 11 and a process time of 35 min. [ABSTRACT FROM AUTHOR]

The development of photoelectrochemical tandem cells for water splitting with electrodes entirely based on metal oxides is hindered by the scarcity of stable p-type oxides and the poor stability of oxides in strongly alkaline and, particularly, strongly acidic electrolytes. As a novelty in the context of transition metal oxide photoelectrochemistry, a bias-free tandem cell driven by simulated sunlight and based on a CuCrO2 photocathode and a WO3 photoanode, both unprotected and free of co-catalysts, is demonstrated to split water while working with strongly acidic electrolytes. Importantly, the Faradaic efficiency for H2 evolution for the CuCrO2 electrode is found to be about 90%, among the highest for oxide photoelectrodes in the absence of co-catalysts. The tandem cell shows no apparent degradation in short-to-medium-term experiments. The prospects of using a practical cell based on this configuration are discussed, with an emphasis on the importance of modifying the materials for enhancing light absorption. [ABSTRACT FROM AUTHOR]

Transition metal oxides have been widely used in microwave-absorbing materials, but how to improve impedance matching is still an urgent problem. Therefore, we introduced urea as a polymer carbon source into a three-dimensional porous structure modified by Co3O4 nanoparticles and explored the influence of different heat treatment temperatures on the wave absorption properties of the composite. The nanomaterials, when calcined at a temperature of 450 °C, exhibited excellent microwave absorption capabilities. Specifically, at an optimized thickness of 9 mm, they achieved a minimum reflection loss (RLmin) of −97.3 dB, accompanied by an effective absorption bandwidth (EAB) of 9.83 GHz that comprehensively covered both the S and Ku frequency bands. On the other hand, with a thickness of 3 mm, the RLmin was recorded as −17.9 dB, with an EAB of 5.53 GHz. This excellent performance is attributed to the multi-facial polarization and multiple reflections induced by the magnetic loss capability of Co3O4 nanoparticles, the electrical conductivity of C, and the unique three-dimensional structure of diatomite. For the future development of bio-based microwave absorption, this work provides a methodology and strategy. [ABSTRACT FROM AUTHOR]

Transition metal oxides ion diffusion channels have been developed for ammonium-ion batteries (AIBs). However, the influence of microstructural features of diffusion channels on the storage and diffusion behavior of NH4+ is not fully unveiled. In this study, by using MnCo2O4 spinel as a model electrode, the asymmetric ion diffusion channels of MnCo2O4 have been regulated through bond length optimization strategy and investigate the effect of channel size on the diffusion process of NH4+. In addition, the reducing channel size significantly decreases NH4+ adsorption energy, thereby accelerating hydrogen bond formation/fracture kinetics and NH4+ reversible diffusion within 3D asymmetric channels. The optimized MnCo2O4 with oxygen vacancies/carbon nanotubes composite exhibits impressive specific capacity (219.2 mAh g-1 at 0.1 A g-1) and long-cycle stability. The full cell with 3,4,9,10-perylenetetracarboxylic diimide anode demonstrates a remarkable energy density of 52.3 Wh kg-1 and maintains 91.9% capacity after 500 cycles. This finding provides a unique approach for the development of cathode materials in AIBs. [ABSTRACT FROM AUTHOR]

Transition metal d-electron oxides with an odd number of electrons per unit cell are expected to form metals with partially occupied energy bands, but exhibit in fact a range of behaviors, being either insulators, or metals, or having insulator-metal transitions. Traditional explanations involved predominantly electron-electron interactions in fixed structural symmetry. The present work focuses instead on the role of symmetry breaking local structural motifs. Viewing the previously observed V-V dimerization in VO2 as a continuous knob, reveals in density functional calculations the splitting of an isolated flat band from the broad conduction band. This leads past a critical percent dimerization to the formation of the insulating phase while lowering the total energy. In VO2 this transition is found to have a rather low energy barrier approaching the thermal energy at room temperature, suggesting energy-efficient switching in neuromorphic computing. Interestingly, sufficient V-V dimerization suppresses magnetism, leading to the nonmagnetic insulating state, whereas magnetism appears when dimerization is reduced, forming a metallic state. This study opens the way to design novel functional quantum materials with symmetry breaking-induced flat bands. [ABSTRACT FROM AUTHOR]

In this work, a porous Co 3 O 4 anode material with capsule–shaped morphology is prepared by a simple solvothermal method and subsequent heat treatment process in air. The as–synthesized CoCO 3 precursor and Co 3 O 4 sample are systematically studied and analyzed by a series of testing technologies, such as XRD, FTIR, FESEM, (HR)TEM, TGA, XPS and N 2 adsorption/desorption measurement. As negative materials in Li–ion batteries, the Co 3 O 4 active material exhibits high charge/discharge specific capacity, good rate performance and satisfactory cycle stability. The excellent electrochemical properties are inevitably related to the structural characteristics of the electrode material itself, including regular morphology, rich pore structure, large specific surface area, high crystallinity, nanoscale particle size, etc. [ABSTRACT FROM AUTHOR]

Developing an efficient system is essential for energy storage, especially sustainable sources of energy, which have expanded significantly in the last few years. However, the fabrication of effective materials proves an aid to solve such crises of high cost and low specific capacitance. Transition and inner transition metal oxides play a significant role in energy storage as well as energy conversion systems. In this research, a novel material CuO/CeAlO 3 nanocomposite is synthesized by sonication technique for supercapacitor applications. The different physical methods including X-ray diffractometer (XRD), Raman and Scanning Electron Microscopy (SEM) were employed to analyze the phase purity, structure as well as morphology of the prepared electrode. Electrochemical investigations concluded that the CuO/CeAlO 3 nanocomposite exhibited specific capacitance of 1091.98 F/g, high energy density of 56.26 Wh/kg, high power density of 304.55 W/kg at 1 A/g current density as well as high cyclic stability after 5000th cycle with lower charge transfer resistance of 0.09 Ω. The electrochemical characteristics of CuO/CeAlO 3 nanocomposite were improved because of the increased area of surface, large active sites and decreased resistance that resulted from the addition of CeAlO 3 with CuO. This research showed the great potential of CuO/CeAlO 3 nanocomposite along with inexpensive fabrication cost and could be used in next-generation energy storage systems. [ABSTRACT FROM AUTHOR]

Transition metal oxides (TMOs) have emerged as promising candidates for spintronic applications due to their unique electronic properties and novel quantum states. The intricate interplay between strong spin-orbit coupling and electronic correlations in TMOs gives rise to distinct spin and orbital textures, leading to enhanced spin-momentum locking and efficient charge-spin interconversion. Remarkably, recent researches have unveiled the significant and highly tunable nature of charge-spin interconversion efficiency in TMOs, which can be manipulated through strategies such as electric field gating, epitaxial strain, and heterostructure engineering. This review provides a comprehensive overview of the recent advances in understanding the electronic band structures of TMOs and their correlation with charge-spin interconversion mechanisms. We summarize the tunability of these properties through various experimental approaches and discuss the potential implications for spintronic device applications. The insights gained from this review can guide future research efforts towards the development of high-performance, energyefficient spintronic devices based on TMOs. [ABSTRACT FROM AUTHOR]

This study presents the synthesis of a multicomponent metal oxide electrocatalyst that increases the activity of the oxygen evolution reaction (OER). We synthesized transition metal oxides (MnOx, FeOx, CoOx, and NiOx) with MoO3 heterostructures through a solid-state reaction approach at low cost. In comparison to the other compositions, CoOx garnered higher attention and demonstrated superior performance on account of its large surface area and varied crystal facets. The MnOx-MoO3, FeOx-MoO3, CoOx-MoO3, and NiOx-MoO3 compositions attained an overpotential of 390 mV, 350 mV, 310 mV, and 340 mV, respectively, at a current density of 10 mA cm−2 in alkaline solution. The performance of OER was enhanced in CoOx-MoO3 at 10 mA cm−2, while FeOx-MoO3 exhibited a lower current density at 100 mA cm−2 than other metal oxides. The CoOx-MoO3 material exhibited a favorable crystal interface transition due to the presence of MoO3 oxide. For the first time, we report on the MoO3-to-(MnOx, FeOx, CoOx, and NiOx) interface crystal transition and the active surface area for OER catalytic activity in water-splitting processes. This investigation intends to develop an electrocatalyst that is capable of producing hydrogen with the use of heterostructure metal oxides. [ABSTRACT FROM AUTHOR]

Transition metal oxides show high activity while still facing the challenges of low mineralization and poor durability in the ozone catalytic oxidation (OCO) of volatile organic compounds (VOCs). Improving the oxygen mobility and low-temperature reducibility of transition metal oxides was found to be an effective way to address the above challenges. Here, highly dispersed Ag was added to Mn3O4 via the co-precipitation oxalate route, and the obtained Ag/Mn3O4 exhibited higher mineralization and stability in benzene catalytic ozonation at room temperature. Compared to Mn3O4, the concentration of CO2 formed from benzene oxidation over Ag/Mn3O4 was significantly increased, from 585.4 ppm to 810.9 ppm, while CO generation was greatly suppressed to only one tenth of its original value (194 ppm vs. 19 ppm). In addition, Ag/Mn3O4 exhibited higher catalytic stability than Mn3O4. The introduction of Ag obviously improved the oxygen mobility and low-temperature reducibility of Mn3O4. Moreover, the highly dispersed Ag also promoted the activity of surface oxygen species and the chemisorption of benzene on Mn3O4. The above physicochemical properties contributed to the excellent catalytic performance and durability of Ag/Mn3O4. This research could shed light on the improvement in VOC mineralization via ozone catalytic oxidation. [ABSTRACT FROM AUTHOR]

Transition metal oxides are considered to be highly promising anode materials for high-energy lithium-ion batteries. While carbon matrices have demonstrated effectiveness in enhancing the electrical conductivity and accommodating the volume expansion of transition metal oxide-based anode materials in lithium-ion batteries (LIBs), achieving an optimized utilization ratio remains a challenging obstacle. In this investigation, we have devised a straightforward synthesis approach to fabricate CuO nano powder integrated with carbon matrix. We found that with the use of a sodium carboxymethyl cellulose (CMC) based binder and fluoroethylene carbonate additives, this anode exhibits enhanced performance compared to acrylonitrile multi-copolymer binder (LA133) based electrodes. CuO@CMC electrodes reveal a notable capacity ~1100 mA h g−1 at 100 mA g−1 following 170 cycles, and exhibit prolonged cycling stability, with a capacity of 450 mA h g−1 at current density 300 mA g−1 over 500 cycles. Furthermore, they demonstrated outstanding rate performance and reduced charge transfer resistance. This study offers a viable approach for fabricating electrode materials for next-generation, high energy storage devices. [ABSTRACT FROM AUTHOR]

Potassium sodium niobate (KNN)‐based piezoelectric ceramics have emerged as a promising alternative to lead‐based systems due to their exceptional properties. While extensive research has focused on improving the electrical properties of KNN‐based ceramics through doping and processing optimization, the concurrent investigation of their mechanical properties has been lacking. This study presents a comprehensive analysis of the mechanical and electrical properties of KNN‐based lead‐free piezoceramics doped with various transition metal oxides and rare earth oxides, based on substantial experimental data. Our findings reveal that the as‐sintered KNN‐based ceramics exhibit not only outstanding electrical properties but also remarkable mechanical robustness compared to conventional toughened lead zirconate titanate (PZT)‐based ceramics. These exceptional electrical and mechanical properties are attributed to the micro‐scale and atomic‐scale structure of the modified KNN‐based ceramics, characterized by a highly condensed structure, an inhomogeneous distribution of nano‐domain structure, and the presence of amorphous intergranular films at grain boundaries. [ABSTRACT FROM AUTHOR]

Nickel ferrites have served as electrode materials in energy storage applications such as batteries and supercapacitors in comparison to other metal oxides, they have a higher theoretical capacitance range. Pristine metal oxides are poor candidates as electrode components in electrochemical applications because of their tendency to aggregate and their less specific surface areas. Herein, we reported wet impregnation method to incorporate Nickel Ferrite (NiFe2O4) to multiwalled carbon nanotubes (MWCNTs) for improved electrochemical performance of nickel ferrites (NiFe2O4). The synthesized materials attained good crystallinity confirmed by X-ray diffraction (XRD). NiFe2O4 nanoparticle adhesions on multiwalled carbon nanotubes have been confirmed by scanning electron microscopy (SEM). UV-DRS was used to measure the bandgap for optical studies. Cyclic Voltammetry (CV), Galvanostatic Charge/Discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS) investigations for supercapacitor applications revealed that synthesized materials demonstrated good electrochemical potential, but MWCNTs supported NiFe2O4 composite attained exceptionally high specific capacitance (CV: 830 F g−1 at 5 mV s−1, GCD:343 F g−1 at current density of 0.1 A g−1) with capacitance retention of 98% at the current density of 0.8 A g−1 after 3500 stability cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • NH 4 PF 6 dual beneficial role, hinders the dendritic growth and accelerate the SEI formation. • Stable lithium deposition stripping over 1500 cycles. • Operando confocal Raman spectroscopy demonstrates the electrolyte degradation in forming the SEI. Lithium-ion batteries (LiBs) with graphite as an anode and lithiated transition metal oxide as a cathode are approaching their specific energy and power theoretical values. To overcome the limitations of LiBs, lithium metal anode with high specific capacity and low negative redox potential is necessary. However, practical application in rechargeable cells is hindered by uncontrolled lithium deposition manifesting, for instance, as Li dendrite growth which can cause formation of dead Li, short circuits and cell failure. The electrochemical behaviour of a protic additive (NH 4 PF 6) in a carbonate-based electrolyte has been investigated by operando confocal Raman spectroscopy, in situ optical microscopy, and X-ray photoelectron spectroscopy, elucidating its functional mechanism. The ammonium cation promotes a chemical modification of the lithium metal anode-electrolyte interphase by producing an N -rich solid electrolyte interphase and chemically modifying the lithium surface morphology by electrochemical pitting. This novel method results in stable lithium deposition and stripping by a decreasing the local current density on the electrode, thus limiting dendritic deposition. [ABSTRACT FROM AUTHOR]

[Display omitted] • The intrinsic mechanism of the external electric field effects on the N 2 adsorption and NN* dissociation performances of three-atom transition metal clusters (TATMCs) is investigated. • Electric fields regulate the charge transfer between TATMCs and NN*, thus affecting the N−N bond activation. • The ICOHP values of two N atoms and E N are not limited by the linear relationship under different electric fields. Three-atom transition metal clusters (TATMCs) with remarkable catalytic activities, especially Nb 3 , Zr 3 , and Y 3 , are proven to be suitable candidates for efficient ammonia production. The pursuit of effective strategies to further promote the ammonia synthesis performance of TATMCs is necessary. In this study, we systematically investigate the effect of external electric fields on tuning the N 2 adsorption and NN* activation performances of Nb 3 , Zr 3 , and Y 3. Our findings demonstrate that the medium and low positive fields promote the N 2 adsorption performance of Nb 3 , while both positive and negative fields enhance nitrogen adsorption on Zr 3. Additionally, electric fields may impede N 2 fixation on Y 3 , yet the N 2 adsorption performance of Y 3 remains considerable. Negative electric fields enhance the NN* activation performance of Nb 3 and Y 3. But only high negative fields weaken the N N bond on Zr 3 , which is attributed to the promotion of the charge accumulation around two N atoms. Notably, Nb 3 and Zr 3 are identified as two TATMCs with the potential for simultaneous optimization of their E N and ICOHP values. This work sheds light on the field effects on the N 2 adsorption and NN* activation performances of TATMCs and guides the design of catalysts for achieving more sustainable ammonia synthesis. [ABSTRACT FROM AUTHOR]

The demand for susceptible and selective hydrogen gas sensors is growing in fuel cells, chemical production, and automotive industries. Detecting H 2 gas at the ppm or ppb level is crucial due to its colourless, odourless, tasteless nature, as well as its flammability and explosiveness. Transition metal dichalcogenides (TMDs) and metal oxide (MO) semiconductors-based hybrid structures have garnered attention in recent years as promising candidates for gas sensing applications owing to their unique properties, including a high surface area, tunable bandgap, and strong gas adsorption. This paper aims to offer insights into the potential of TMD-MO hybrid structures as the next generation of hydrogen gas sensing platforms, contributing to developing highly sensitive and selective gas sensors for diverse industrial applications. TMD-MO hybrid structures are vital for detecting hydrogen gas with high sensitivity and selectivity, which are essential for safe and efficient hydrogen-based systems. Furthermore, these hybrid structures hold significant potential for further customization and enhancement to suit specific applications. Overall, TMD-MO hybrid structures offer a promising avenue for developing next-generation hydrogen gas sensors useable in various industrial applications and promoting a safe and sustainable hydrogen economy. [ABSTRACT FROM AUTHOR]

Nowadays metal oxide nanoparticles and transition metal dichalcogenides play a vital role in various areas like optical sensors, solar cells, energy storage devices, gas sensors and biomedical applications. In the current research work, we synthesized ZrSe2 nanoparticles by hydrothermal method. The ZrSe2 nanoparticles were synthesis using precursors such as ZrOCl2.8H2O and Na2SeO3.5H2O in the addition of surfactant cetyl trimethyl ammonia bromide CTAB and reductant hydrazine hydrate, respectively. Synthesized ZrSe2 nanopowder thick films were developed on a glass substrate using the screen printing method. The structural properties of ZrSe2 powder were studied by X-ray diffraction (XRD). The X-ray diffraction analysis revealed that the hexagonal crystal structure and crystalline size were found to be 55.75 nm. The thick films of ZrSe2 were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX). The surface morphological analysis of ZrSe2 nanostructured thick film shows hierarchical nanoparticles. The energy band gap of synthesized powder was calculated using a Tauc plot from UV-visible spectroscopy. The gas-sensing properties of ZrSe2 thick films were studied. The developed ZrSe2 thick films show maximum sensitivity and selectivity towards the ammonia NH3 gas at an operating temperature of 120°C and the gas concentration was 500 ppm. The developed thick films show fast response and recovery time. [ABSTRACT FROM AUTHOR]

Binary transition metal chalcogenides and reduced graphene oxide exhibit significant potential for energy storage devices due to their superior electronic conductivity and capacity, surpassing that of single-metal sulfides, owing to their more extensive redox reactions. In this report, we introduce a novel synthesis method for producing a mixed-phase MnSe2/CoSe2 nanocomposite wrapped with reduced graphene oxide (rGO) sheets, designed specifically for supercapacitor applications. The MnSe2/CoSe2 hybrid material was synthesized using an ultrasonic assisted hydrothermal technique, followed by the preparation of the rGO/MnSe2/CoSe2 hybrid composite. The structural characterization was conducted employing x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and Raman techniques. Brunauer–Emmett–Teller (BET) analysis demonstrated a significant specific surface area (66.5 m2/g) and a pore size distribution of 28.4 nm in rGO-MnSe2/CoSe2. The interconnected ultrathin rGO nanosheets and conductive carbon layer contributed to the exceptional conductivity and stability achieved by the rGO/MnSe2/CoSe2 composite electrode. The electrochemical performance was assessed using a three-electrode setup in a 3 M KOH solution, with nickel foam as the current collector. The working electrode, consisting of rGO/MnSe2/CoSe2, acetylene black and PVDF in an 80:15:5 weight ratio, demonstrated specific capacitance of 1214 F g−1 and cycling stability of 88% retention after 5000 cycles at 1 A g−1. An asymmetric supercapacitor, constructed using a tailored electrode composition, achieved energy density of 28.6 Wh kg−1 at 2100 W kg−1 and high power density of 888 W kg−1 at 49.7 Wh kg−1. [ABSTRACT FROM AUTHOR]

Tunable optical information storage is crucial in artificial retinal systems for mimicking neurobiological visual characteristics. The perception and storage of light signals rely heavily on the regulation of the conductivity states of memristor materials (e.g., transition metal oxides). Controlling light memristor behavior via defects and polymorphic phases remains underexplored and differs from traditional plasticity training via repeated testing. In this study, defect‐driven ultraviolet light perception and memristor storage with phase transitions in vanadium dioxide (VO2) thin films are presented. The effects of oxygen defects and the corresponding polymorphic phases on ultraviolet light memristors are investigated. The dependence of phonon vibrations and insulator–metal transition behavior on defect levels are revealed. Self‐doping and polymorphs enable VO2 to exhibit distinct ultraviolet memristor performance. It is anticipated that defect‐driven light memristors significantly contribute to the realization of artificial synaptic devices and the implementation of advanced electronic neuron systems. [ABSTRACT FROM AUTHOR]

Renewable and non-renewable energy harvesting and its storage are important components of our everyday economic processes. Lithium-ion batteries (LIBs), with their rechargeable features, high open-circuit voltage, and potential large energy capacities, are one of the ideal alternatives for addressing that endeavor. Despite their widespread use, improving LIBs' performance, such as increasing energy density demand, stability, and safety, remains a significant problem. The anode is an important component in LIBs and determines battery performance. To achieve high-performance batteries, anode subsystems must have a high capacity for ion intercalation/adsorption, high efficiency during charging and discharging operations, minimal reactivity to the electrolyte, excellent cyclability, and non-toxic operation. Group IV elements (Si, Ge, and Sn), transition-metal oxides, nitrides, sulfides, and transition-metal carbonates have all been tested as LIB anode materials. However, these materials have low rate capability due to weak conductivity, dismal cyclability, and fast capacity fading owing to large volume expansion and severe electrode collapse during the cycle operations. Contrarily, carbon nanostructures (1D, 2D, and 3D) have the potential to be employed as anode materials for LIBs due to their large buffer space and Li-ion conductivity. However, their capacity is limited. Blending these two material types to create a conductive and flexible carbon supporting nanocomposite framework as an anode material for LIBs is regarded as one of the most beneficial techniques for improving stability, conductivity, and capacity. This review begins with a quick overview of LIB operations and performance measurement indexes. It then examines the recently reported synthesis methods of carbon-based nanostructured materials and the effects of their properties on high-performance anode materials for LIBs. These include composites made of 1D, 2D, and 3D nanocarbon structures and much higher Li storage-capacity nanostructured compounds (metals, transitional metal oxides, transition-metal sulfides, and other inorganic materials). The strategies employed to improve anode performance by leveraging the intrinsic features of individual constituents and their structural designs are examined. The review concludes with a summary and an outlook for future advancements in this research field. [ABSTRACT FROM AUTHOR]

Increasing the energy density and power of supercapacitors through hybrids of carbonaceous materials and metal oxides continues to be the subject of numerous research works. The correlation between specific capacitance and the properties of materials used as electrodes attracts great interest. In the present study, we investigated composites (GO/Mn3O4) prepared by the hydrothermal method with a variable ratio of GO/Mn3O4 and tested them as supercapacitor electrode materials in three- and two-electrode cells. The chemical characterization carried out by X-ray photoelectron spectroscopy and the adsorption techniques used allowed the determination of the surface carbon and oxygen content, as well as its textural properties. In this work, we analyzed the contribution of the double layer and the Faradaic reactions to the value of the final capacitance of the synthesized materials. Beyond empirically obtaining the electrochemical properties, these have been related to the physicochemical characteristics of the hybrids to help design materials with the best performance for supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Tuning interphase chemistry to stabilize high-voltage NaNi 1/3 Fe 1/3 Mn 1/3 O 2 cathode via bonding superionic conductor interface. [Display omitted] • NASICON-type Na 3 V 2 (PO 4) 3 is bonded on NaNi 1/3 Fe 1/3 Mn 1/3 O 2 surface. • The coating layer inhibits surface parasitic reactions and TMs dissolution. • Fast Na+ kinetic and high rate capacity are achieved for the composite electrode. Unstable cathode/electrolyte interphase and severe interfacial side reaction have long been identified as the main cause for the failure of layered oxide cathode during fast charging and long-term cycling for rechargeable sodium-ion batteries. Here, we report a superionic conductor (Na 3 V 2 (PO 4) 3 , NVP) bonding surface strategy for O3-type layered NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (NFM) cathode to suppress electrolyte corrosion and near-surface structure deconstruction, especially at high operating potential. The strong bonding affinity at the NVP/NFM contact interface stabilizes the crystal structure by inhibiting surface parasitic reactions and transition metal dissolution, thus significantly improving the phase change reversibility at high desodiation state and prolonging the lifespan of NFM cathode. Due to the high-electron-conductivity of NFM, the redox activity of NVP is also enhanced to provide additional capacity. Therefore, benefiting from the fast ion transport kinetics and electrochemical Na+-storage activity of NVP, the composite NFM@NVP electrode displays a high initial coulombic efficiency of 95.5 % at 0.1 C and excellent rate capability (100 mAh g−1 at 20 C) within high cutoff voltage of 4.2 V. The optimized cathode also delivers preeminent cyclic stability with ∼80 % capacity retention after 500 cycles at 2 C. This work sheds light on a facile and universal strategy on improving interphase stability to develop fast-charging and sustainable batteries. [ABSTRACT FROM AUTHOR]

A carbon nanotube and N -doped graphene quantum dot modified (NiMn) Co 2 O 4 composite film was successfully prepared to improve the performance of supercapacitor electrode materials. [Display omitted] • A carbon nanotube and N -doped graphene quantum dot modified (NiMn)Co 2 O 4 composite film was successfully prepared. • The CNT/P-(NiMn)Co 2 O 4 @NGQD electrode shows the excellent specific capacity of 2172.0 F g−1. • The embedding of NGQD provides abundant redox sites and improves the electrochemical performance of CNT/P-(NiMn)Co 2 O 4 @NGQD. • The asymmetric supercapacitor devices CNT/P-(NiMn)Co 2 O 4 @NGQD//AC delivers a high energy density of 94.44 Wh kg−1. The integration of ternary metal oxides into carbon materials is anticipated to significantly boost the electrochemical performance of supercapacitor electrodes. This article synthesized carbon nanotubes (CNT)/(NiMn)Co 2 O 4 composite materials using a straightforward hydrothermal method and subsequently prepared composite thin films of CNT/P-(NiMn)Co 2 O 4 @NGQD by phosphating and incorporating nitrogen-doped graphene quantum dots (NGQD). These films served as the functional electrode material for supercapacitors, enhancing their performance capabilities. The specific capacity of CNT/P-(NiMn)Co 2 O 4 @NGQD was measured at 2172.0 F g−1 at a current density of 1 A g−1, maintaining a capacitance of 1954.0 F g−1 at 10 A g−1, thus demonstrating excellent rate performance. Electrochemical impedance spectroscopy (EIS) further revealed enhancements in electrolyte flow dynamics and capacitance behavior post-NGQD introduction. The energy density of the composite material reached 94.4 Wh kg−1 at power density of 800 W kg−1, demonstrating superior electrochemical performance. The enhancement in these electrochemical properties is attributed to the high specific surface area and active sites of CNT/P-(NiMn)Co 2 O 4 @NGQD films, along with the synergistic effects of NGQD and metal ions facilitating rapid electrons and charge transfer. This work provides new insights into developing high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Ov-Co 2 NiO 4 /NC nanoflowers were successfully synthesized using a straightforward method, targeting high-performance PIHCs. The nanoflower architecture increases the contact area between the active material and the electrolyte. DFT calculations reveal that oxygen vacancies enhance the charge density across the Fermi level in Co 2 NiO 4 and increase the interatomic distance between adjacent cobalt and nickel atoms to 3.370 Å. Additionally, N-doped carbon supports facilitate faster charge transfer, augment electrostatic energy storage, and prevent the structural collapse of Co 2 NiO 4. These structural enhancements improve electrochemical reaction kinetics, increase K+ binding energy (−2.87 eV), and mitigate structural changes during K+ storage. [Display omitted] • A facile synthesis approach to fabricate nitrogen-doped carbon-supported oxygen vacancy-rich Co 2 NiO 4 nanoflowers. • Oxygen vacancies could expand the interatomic distances between adjacent cobalt and nickel atoms to 3.370 Å. • N-doped carbon carriers further accelerate charge transfer, increase the electrostatic energy storage and inhibit the structural collapse of Co 2 NiO 4. • Ov-Co 2 NiO 4 /NC NF exhibits a specific capacitance of 1104 F g−1 at 0.5 A g−1 and capacitance retention of 91.48 % after 6500 cycles in 6 M KOH electrolyte. • The assembled potassium-ion hybrid supercapacitors demonstrates an energy density of 47.8 Wh kg−1 and an ultra-high power density of 376 W kg−1. Transition metal oxides represent a promising category of pseudocapacitive materials for potassium-ion hybrid supercapacitors (PIHCs) characterized by high energy density. Nevertheless, their utility is hindered by intrinsic low conductivity, restricted electrochemical sites, and notable volume expansion, all of which directly contribute to the degradation of their electrochemical performance, thereby limiting their practical applicability in supercapacitor systems. In this study, we present a facile synthesis approach to fabricate nitrogen-doped carbon-supported oxygen vacancy-rich Co 2 NiO 4 nanoflowers (Ov-Co 2 NiO 4 /NC NFs) featuring tunable surface layering and electron distribution. The nanoflower structure augments the contact area between the material and the electrolyte. Density functional theory (DFT) calculations reveal oxygen vacancies could bring an enhanced charge density across the entire Fermi level in Co 2 NiO 4 and expand the interatomic distances between adjacent cobalt and nickel atoms to 3.370 Å. N-doped carbon carriers further accelerate charge transfer, increase the electrostatic energy storage and inhibit the structural collapse of Co 2 NiO 4. These structural modifications serve to improve electrochemical reaction kinetics, augment the binding energy of K+ (−2.87 eV), and mitigate structural variations during K+ storage. In a 6 M KOH electrolyte, Ov-Co 2 NiO 4 /NC NF exhibits a specific capacitance of 1104 F g−1 at a current density of 0.5 A g−1, with a remarkable capacitance retention rate of 91.48 % after 6500 cycles. Furthermore, the assembled PIHCs demonstrate an energy density of 47.8 Wh kg−1 and an ultra-high power density of 376 W kg−1, alongside notable cycle stability, retaining 90.13 % of its capacitance after 8000 cycles in a 6 M KOH electrolyte. [ABSTRACT FROM AUTHOR]

Entropy-induced high-density grain boundaries is favorable for improved capacity and cycling stability. [Display omitted] • Co-free high entropy oxide was synthesized by a simple solution combustion method. • HEO anode exhibits high capacity (1374 mAh g−1) and excellent cycling stability. • High-density grain boundaries contribute to improved capacity and cycling stability. Transition metal oxides (TMOs) with high discharge capacity are considered as one of the most promising anodes for lithium-ion batteries. However, the practical utilization of TMOs is largely limited by cycling stability issues arising from volume expansion, structural collapse. In this study, we synthesized a high-entropy spinel oxide material (FeCrNiMnZn) 3 O 4 using a solution combustion method. With the implementation of five cations through high-entropy engineering, the agglomeration and expansion of the electrode materials during charging and discharging are suppressed, and the cycling stability is enhanced. The results demonstrate that entropy-induced high-density grain boundaries and the reversibility of spinel structure contribute to improved capacity and cycling stability. Herein, (FeCrNiMnZn) 3 O 4 provides a high capacity (1374 mAh g−1) at 0.1 A g−1 and superior cycling stability (almost 100 %) during 200 cycles with a current density of 0.5 A g−1. The study provides valuable understanding for designing the high entropy oxides anode electrodes. [ABSTRACT FROM AUTHOR]

A self-supporting film embedded with nitrogen doped graphene quantum dots into (Ni 0.5 Co 0.5) 3 V 2 O 8 nanosheets has been successfully prepared for high-performance supercapacitors. [Display omitted] • A self-supporting film embedded with (NGQD) into (Ni 0.5 Co 0.5) 3 V 2 O 8 nanosheets has been successfully prepared. • The (Ni 0.5 Co 0.5) 3 V 2 O 8 /NGQD@CNT electrode shows the excellent specific capacity of 3018.2 F g−1. • The embedding of NGQD provides abundant redox sites and improves the electrochemical performance of (Ni 0.5 Co 0.5) 3 V 2 O 8. • The asymmetric supercapacitor devices (Ni 0.5 Co 0.5) 3 V 2 O 8 /NGQD@CNT//AC delivers a high energy density of 166.2 Wh kg−1. To improve the electrochemical performance of positive electrode materials, constructing graded nanostructures is a worthwhile approach. This study successfully synthesized nitrogen-doped graphene quantum dots (NGQD) modified (Ni 0.5 Co 0.5) 3 V 2 O 8 on a carbon nanotube (CNT) substrate to construct self-supporting electrodes for high-performance supercapacitors. The (Ni 0.5 Co 0.5) 3 V 2 O 8 nanosheets were successfully wrapped onto the CNT surface through a solution impregnation process, which increased the specific surface area and interlayer spacing of the material. Furthermore, the electrochemical properties of the electrode material underwent significant enhancement due to the synergistic interplay between metal ions and the numerous redox centers. The embedding of the NGQD enriched the materials with active sites and further improved its specific capacity without compromising the structure intergrity of the layer configuration. Using CNT as the substrate ensured the self-supporting nature of the electrode. Consequently, the (Ni 0.5 Co 0.5) 3 V 2 O 8 /NGQD@CNT composite exhibits an ultra-high specific capacitance of 3018.2 F g−1 at 1 A g−1 and 2332 F g−1 at 10 A g−1. The asymmetric supercapacitor constructed with (Ni 0.5 Co 0.5) 3 V 2 O 8 /NGQD@CNT and activated carbon (AC) presented an impressive energy density of 160.2 Wh kg−1 at a power density of 800 W kg−1. After 8000 charge–discharge cycles, the capacity retention rate was 78.5 %, with a Coulo mbic efficiency consistently above 98 %. [ABSTRACT FROM AUTHOR]

[Display omitted] The design and fabrication of high-performance, inexpensive and durable electrocatalyst toward hydrogen evolution reaction (HER) is supremely significant for alleviating energy crisis and environmental concerns, but still remaining challenging. Herein, we develop an experimental work based on etching and reduction strategy to reveal the remarkable effect of cation/anion co-doping in CoMoO 4 on its intrinsic HER activity. The CoMoO 4 with Fe and B incorporation (Fe/B-CoMoO 4) exhibits a current density of 10 mA cm−2 with strikingly low potential of 38 mV coupling with Tafel slope of 51 mV dec-1, and manifesting a robust durability for 100 h with no attenuation, which is comparable to the state-of-the-art commercial Pt/C catalyst. The collective experimental and theoretical findings concomitantly illustrate that the enhanced performances are due to the strong synergistic effect resulting from the co-doping of Fe and B, which plays a pivotal role in finely tuning the electronic structure of CoMoO 4 , further optimizing the adsorption free energy of H intermediates and shifting the center of the d -band of Fe/B-CoMoO 4 away from the Fermi level. This fantastic work highlights the critical role of foreign element incorporating for optimizing electronic structure of transition metal oxides toward HER, and offers valuable guiding principles for rational design of more efficient energy conversion devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Defectivation of Bi 2 O 3 and compositing with rGO is simultaneously realized by a one-step reducing method. • The Bi 2 O 3 -rGO-100 anode exhibits a high specific capacitance of 1053F/g at 1 A/g. • The Ni 3 Co 2 -rGO//Bi 2 O 3 -rGO-100 battery-type pouch-cell supercapacitor achieves an energy density of 118.5 Wh kg−1 at a power density of 850 W kg−1. • Two series-connected pouch-cell supercapacitor successfully illuminate 88 LED lamps for 12 min. We prepare bismuth oxide-reduced graphene oxide (Bi 2 O 3 -rGO) composite anode using a one-step chemical precipitation/reduction method. Under a reducing atmosphere, oxygen atoms on the surface of Bi 2 O 3 are gradually removed and neighboring oxygen atoms migrate to the surface, leaving oxygen vacancies. Defective Bi 2 O 3 enhances the number of active sites, providing additional pseudocapacitive performance. The transition metal oxide-based Bi 2 O 3 acts as an anode, providing capacitive performance that far exceeds that of conventional carbon materials. Moreover, the introduction of rGO forms a conductive network for Bi 2 O 3 , improving capacitive contribution and ion diffusion capabilities for the electrode. The Bi 2 O 3 -rGO-100 (GO added at 100 mg) exhibits a high specific capacitance of 1053F/g at 1 A/g, significantly higher than that of Bi 2 O 3 (866F/g). The Bi 2 O 3 -rGO-100 anode and Ni 3 Co 2 -rGO cathode are assembled into a battery-type supercapacitor. The coin-cell device achieves an energy density of 88.2 Wh kg−1 at a power density of 850 W kg−1. The Ni 3 Co 2 -rGO//Bi 2 O 3 -rGO-100 pouch-cell device demonstrates an extremely low R ct of 0.77 Ω. At a power density of 850 W kg−1, the energy density reaches 118.5 Wh kg−1, and remains 67.4 Wh kg−1 at 8500 W kg−1. [ABSTRACT FROM AUTHOR]

A synergism between CoMo and Fe 2 O 3 dominating the prominent HER and OER performance is demonstrated. [Display omitted] • Novel CoMo/Fe 2 O 3 /NF nanoarchitecture is designed for overall water splitting. • The optimized CoMo/Fe 2 O 3 /NF exhibits outstanding HER and OER catalytic activity. • The constructed overall water-splitting cell attains 10mA cm−2 at 1.5 V. • The synergistic effect between multiple metals dominates the high catalytic activity. Constructing bifunctional non-precious metal electrocatalysts with advanced industrial value and excellent electrocatalytic performance to achieve efficient overall water splitting is important but difficult. Herein, a heterogeneous electrocatalyst comprising of CoMo alloys anchored Fe 2 O 3 nanosheets was prepared by hydrothermal and electrodeposition methods. The strongly coupled interfaces between the CoMo alloys and Fe 2 O 3 nanosheets promote charge redistribution, which could improve electron transfer efficiency and accelerate reaction kinetics, potentially optimizing reactant adsorption energy. Further density functional theory (DFT) calculations reveal that the construction of CoMo/Fe 2 O 3 /NF heterostructured catalyst facilitates to promote interfacial charge redistribution and enhance charge transfer capacity, thus boosting the catalytic performance. Benefiting from this, the optimal CoMo/Fe 2 O 3 /NF heterostructure demonstrates a minimal overpotential of 71 mV at 10 mA cm−2 for the HER and 266 mV at 50 mA cm−2 for the OER. Remarkably, the catalyst served as a bifunctional electrode for water splitting, resulting in a cell voltage down to 1.5 V at a current density of 10 mA cm−2. This research provides an effective way for the construction of non-precious iron oxides-based bifunctional electrocatalysts using alloy/metal oxide interfacial engineering strategy. [ABSTRACT FROM AUTHOR]

Zeolite imidazole framework −8 (ZIF-8) was used as the encapsulation layer to improve the stability and activity of ZnO nanoparticles. Under the voltage of 2.0 V vs.RHE, the stability test could be carried out for 60 h, and the yield of H 2 O 2 did not decrease significantly. [Display omitted] A promising method of producing hydrogen peroxide (H 2 O 2) is the electrochemical two-electron water oxidation reaction (2e− WOR). In this process, it is important to design electrocatalysts that are both earth abundant and environmentally friendly, as well as offering high stability and production rates. The research of WOR catalysts, such as the extensively used transition metal oxides, is mainly focused on the modification of transition metal elements. Few studies pay attention to the protective heterostructure of metal oxides. Here, we demonstrate for the first time an organometallic skeleton protection strategy to develop highly stable WOR catalysts for H 2 O 2 generation. Unlike the pure ZnO and zeolite imidazole framework-8 (ZIF-8) catalysts, ZnO@ZIF-8 enabled the production of hydrogen peroxide at high voltages. The experimental results demonstrate that the ZnO@ZIF-8 catalyst stably generates H 2 O 2 even under a high voltage of 3.0 V vs. RHE, with a yield reaching 2845.819 μmolmin−1 g−1. ZnO@ZIF-8 shows a relatively low overpotential, with a current density of 10 mA cm−2 and an overpotential of 110 mV. The ZnO@ZIF-8 catalyst's maximal FE value was 4.72 %. Moreover, the ZnO@ZIF-8 catalyst exhibits remarkable durability even after an extended 60-hour stability test. Operando Raman and theoretic calculation analyses reveal that the metal–organic skeleton being encapsulated on the metal oxide surface synergizes with each other, not only expanding the electrochemical surface area, but also adjusting the catalyst metal sites' adsorption capacity. A novel approach to the modification of 2e− WOR metal oxide catalyst is presented in this work. [ABSTRACT FROM AUTHOR]

Samples in the La 2 MoO 6 – Sm 2 MoO 6 – MoO 3 system were obtained using the solid-state synthesis method. The phase formation in the given compositional section was firstly studied, and the homogeneity region of the fluorite-like lanthanum-samarium molybdate was determined, as confirmed by XRD analysis including Rietveld refinement and SEM with energy-dispersive microanalysis. The fluorite-like phase contains less molybdenum than the isostructural neodymium molybdate Nd 5 Mo 3 O 16+δ. The homogeneity region of fluorite-like solid solutions has been determined, which corresponds to the La 5-x Sm x Mo 2.75 O 15.75 section in the composition range 2.5 ≤ x ≤ 3.5. The crystal structure is characterized by the splitting of cation positions and the presence of excess oxygen in the octahedral voids of the structure. Oxygen atoms in the octahedral positions are displaced from the center of the voids and enter into the molybdenum coordination sphere. The density of single-phase ceramic samples increases with the increase in samarium content. The conductive properties of single-phase ceramics were investigated in an air atmosphere using impedance spectroscopy. The total conductivity was ∼10−2 S cm−1 for La 2.5 Sm 2.5 Mo 2.75 O 15.75 at 800 °C. The grain bulk conductivity exhibits a break at a temperature of approximately 600 °C, which may be explained by the depletion of charge carriers in the structure. [ABSTRACT FROM AUTHOR]

Nanocomposites of SrBi (2-X) (CF) X Nb 2 O 9 (SBNCF) (CF=CoFe 2 O 4 for X = 0.0 to 0.5 with a step increment of 0.1) were synthesized using the hydrothermal method and characterized for their structural, morphological, elastic, and optical properties. The incorporation of CF into SrBi 2 Nb 2 O 9 (SBN) resulted in hybrid composites with tailored properties. X-ray Diffraction (XRD) with Rietveld refinement analysis confirmed the formation of orthorhombic SBN and spinel CF phases. Field Emission Gun Scanning Electron Microscopy (FEG-SEM) revealed that SBN exhibits a plate-like morphology, with the incorporation of CF into the SBN matrix resulting in both plate-like and octahedral-shaped grains. The Brunauer–Emmett–Teller (BET) method was used to determine the pore radius and surface area, both of which were found to have increased, indicating an enhancement in photocatalytic performance. The presence of the constituent elements in the prepared compositions was confirmed by Energy Dispersive Spectroscopy (EDS). Fourier Transform Infrared Spectroscopy (FTIR) spectra were used to determine elastic properties, suggesting potential applications in electronic noise filtering. From Diffuse Reflectance Spectroscopy (DRS), a recognizable semiconducting behavior and band gap bowing were noticed in SBNCF nanocomposites on the obtained energy band gap values (2.20 eV–1.56 eV) compared to the SBN host matrix (3.16 eV). The materials exhibited strong emission peaks at 470 nm, 528 nm, 584 nm, and 703 nm upon the excitation of 425 nm light using Photoluminescence (PL) spectroscopy. The white emission was predominant at room temperature in all the produced samples and the corresponding color temperature values range from 5865.93 K to 7599.05 K from the CIE diagram. The SBNCF materials are promising candidates in photocatalytic reactions and white light-emitting diodes (w-LEDs) based on their enhanced optical properties. [ABSTRACT FROM AUTHOR]

Glasses formed from transition metal oxides have shown tailorable electrical and optical properties depending on the valence state and individual element. Vanadate glasses have received specific attention for their high conductivities as compared to most glass families. In this study, the frequency‐dependent capacitance and direct current (dc) conductivity properties of alkaline earth vanadate glasses were investigated. Glasses in the xSrO–(100 − x)V2O5 and xBaO–(100 − x)V2O5 systems, where x = 30, 40, and 50 in mol%, were prepared via melt‐quench synthesis. Capacitance measurements were used to calculate dielectric constants, dielectric loss, and alternating current (ac) conductivity for each sample. Dielectric constants varied between 10–13 and 14–16 for SrO–V2O5 and BaO–V2O5 glasses, respectively, at 1 MHz. Current measurements were made as a function of temperature and voltage for each glass sample. A strong dependence on vanadate content was noted where temperature had a less strong effect. Activation energies were calculated to describe electrical transport mechanisms. All samples showed activation energies governed by electron hopping mechanisms. Such vanadate glasses have properties suitable for applications as cathode materials for batteries, solid state electrolytes, and conductive glass paste with potential for electro‐optic effects involving nonlinear processes. [ABSTRACT FROM AUTHOR]

[Display omitted] Water splitting is a promising technique for clean hydrogen production. To improve the sluggish hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), the development of efficient bifunctional electrocatalysts for both HER and OER is urgent to approach the scale-up applications of water splitting. Nowadays transition metal oxides (TMOs) are considered as the promising electrocatalysts due to their low cost, structural flexibility and stability, however, their electrocatalytic activities are eager to be improved. Here, we synthesized waxberry-like hydrophilic Co-doped ZnFe 2 O 4 electrocatalysts as bifunctional electrocatalysts for water splitting. Due to the enhanced active sites by electronic structure tuning and modified super-hydrophilic characteristics, the spinel ZFO-Co 0.5 electrocatalyst exhibits excellent catalytic activities for both OER and HER. It exhibits a remarkable low OER overpotential of 220 mV at a current density of 10 mA cm−2 and a Tafel slope of 28.2 mV dec-1. Meanwhile, it achieves a low overpotential of 73 mV at a current density of 10 mA cm−2 with the Tafel slope of 87 mV dec-1 for HER. In addition, for water electrolysis device, the electrocatalytic performance of ZFO-Co 0.5 ||ZFO-Co 0.5 surpasses that of commercial IrO 2 ||Pt/C. Our work reveals that the hydrophilic morphology regulation combined with metallic doping strategy is a facile and effective approach to synthesize spinel TMOs as excellent bifunctional electrocatalyst for water splitting. [ABSTRACT FROM AUTHOR]

Thermal switches that switch the thermal conductivity (κ) of the active layers are attracting increasing attention as thermal management devices. For electrochemical thermal switches, several transition metal oxides (TMOs) are proposed as active layers. After electrochemical redox treatment, the crystal structure of the TMO is modulated, which results in the κ switching. However, the κ switching width is still small (<4 W m−1 K−1). In this study, it demonstrates that LaNiOx‐based solid‐state electrochemical thermal switches have a κ switching width of 4.3 W m−1 K−1. Fully oxidized LaNiO3 (on state) has a κ of 6.0 W m−1 K−1 due to the large contribution of electron thermal conductivity (κele, 3.1 W m−1 K−1). In contrast, reduced LaNiO2.72 (off state) has a κ of 1.7 W m−1 K−1 because the phonons are scattered by the oxygen vacancies. The LaNiOx‐based electrochemical thermal switch is cyclable of κ and the crystalline lattice of LaNiOx. This electrochemical thermal switch may be a promising platform for next‐generation devices such as thermal displays. [ABSTRACT FROM AUTHOR]

Highlights: Oxygen-vacancy-rich SiC@MoO3 nanocomposite with strong reflection loss (− 50.49 dB at 1.27 mm thickness) and broadband absorption band (8.72 GHz at 2.68 mm thickness) were constructed via in situ etching strategy. The presence of oxygen vacancy leads to an increased conductive loss and defect-induced dipole polarization, which plays significant role in attenuating the incident electromagnetic wave. Defect engineering in transition metal oxides semiconductors (TMOs) is attracting considerable interest due to its potential to enhance conductivity by intentionally introducing defects that modulate the electronic structures of the materials. However, achieving a comprehensive understanding of the relationship between micro-structures and electromagnetic wave absorption capabilities remains elusive, posing a substantial challenge to the advancement of TMOs absorbers. The current research describes a process for the deposition of a MoO3 layer onto SiC nanowires, achieved via electro-deposition followed by high-temperature calcination. Subsequently, intentional creation of oxygen vacancies within the MoO3 layer was carried out, facilitating the precise adjustment of electromagnetic properties to enhance the microwave absorption performance of the material. Remarkably, the SiC@MO-t4 sample exhibited an excellent minimum reflection loss of − 50.49 dB at a matching thickness of 1.27 mm. Furthermore, the SiC@MO-t6 sample exhibited an effective absorption bandwidth of 8.72 GHz with a thickness of 2.81 mm, comprehensively covering the entire Ku band. These results not only highlight the pivotal role of defect engineering in the nuanced adjustment of electromagnetic properties but also provide valuable insight for the application of defect engineering methods in broadening the spectrum of electromagnetic wave absor ption effectiveness. SiC@MO-t samples with varying concentrations of oxygen vacancies were prepared through in-situ etching of the SiC@MoO3 nanocomposite. The presence of oxygen vacancies plays a crucial role in adjusting the band gap and local electron distribution, which in turn enhances conductivity loss and induced polarization loss capacity. This finding reveals a novel strategy for improving the absorption properties of electromagnetic waves through defect engineering. [ABSTRACT FROM AUTHOR]