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The incorporation of Ni-O-Co configurations stimulates an enhanced π -donation effect of the Co-O bond, which facilitates the hybridization between the O 2 p and Co 3 d orbitals, thereby boosting charge transfer kinetics during electrochemical processes. [Display omitted] • 10%Co-NM nanorods were prepared by hydrothermal and subsequent heat treatment. • The incorporation of Ni-O-Co configurations stimulates an enhanced π-donation effect of the Co-O bond. • The optimized 10 %Co-NM electrode has a remarkable specific capacity of 557.8 C·g−1 at 1 A g−1. • The 10 %Co-NM//FeOOH ASC device delivered an impressive energy density of 63.58 Wh kg−1 at 805.38 W kg−1. NiMoO 4 (NM) has garnered significant attention due to its rich d -orbital electronic structure and multivalent electroactive cations. However, the inherently low electrical conductivity of NM limits its reaction kinetics. Herein, cobalt-substituted NM (Co-NM) nanorods were prepared via a hydrothermal reaction followed by subsequent thermal treatment. The incorporation of Ni-O-Co configurations stimulates an enhanced π -donation effect of the Co-O bond, facilitating the hybridization between the O 2 p and Co 3 d orbitals and thereby boosting charge transfer kinetics during electrochemical processes. The optimized 10 %Co-NM nanorods demonstrated a remarkable specific capacity of 557.8 C·g−1 at 1 A·g−1. Furthermore, an asymmetric supercapacitor constructed with 10 %Co-NM as the positive electrode and FeOOH as the negative electrode, achieved a significant energy density of 63.58 Wh·kg−1 at a power density of 805.38 W·kg−1. Thus, our work provides new insights into the rational design of stable bridging configurations to significantly improve electrochemical reaction kinetics. [ABSTRACT FROM AUTHOR]

As energy resources become increasingly scarce and environmental issues grow more pressing, hydrogen is emerging as a promising alternative to traditional fuels. In this work, rod-shaped NiMoO4-Sx-c electrolytic water HER catalysts with surface particles attached were prepared by solvothermal vulcanization and calcination reduction based on the configuration of NiMoO4 precursors with different NiMo atom ratios. NiMoO4 Sx-c achieved current densities of 10 mA cm−2 and 100 mA cm−2 at overpotentials of 105 mV and 256 mV, respectively. At 100 mA cm−2, the catalytic performance of the electrode did not change within 50 h, which proved that the treated catalyst had excellent stability. The excellent HER performance was attributed to the formation of cross-linked NiS2 and MoS2 heterostructures on its surface due to the vulcanization and calcination reduction processes, thereby increasing the H adsorption energy. Concurrently, during the vulcanization process, particles were deposited on the surface of the smooth rod-like structure, which improved the hydrophilic/hydrophobic properties of the catalyst, enhanced the diffusion of the electrolyte, and ensured the rapid release of bubbles. This research not only provides a new strategy for synthesizing efficient HER electrocatalysts but also promotes the development of efficient electrolytic water catalysts. [ABSTRACT FROM AUTHOR]

The rational design of heterojunction photocatalysts enabling fast transportation and efficient separation of photoexcited charge carriers is the key element in visible light-driven photocatalyst systems. Herein, we develop a unique Z-scheme heterojunction consisting of NiMoO4 microflowers (NMOF) and ZIF67, referred to as ZINM (composite), for the purpose of antibiotic degradation. ZIF67 was produced by a solution process, whereas NMOF was synthesized via coprecipitation with a glycine surfactant. The NMOF exhibited a monoclinic phase with a highly oriented, interconnected sheet-like morphology. The ZINM showed better optical and charge transfer characteristics than its constituents, ZIF67 and NiMoO4. Consequently, the developed heterojunction photocatalysts exhibited superior photocatalytic redox capability; the ZINM30 (the composite with 30 wt.% of NiMoO4 loaded) could degrade 91.67% of tetracycline and 86.23% of norfloxacin within 120 min. This enhanced photocatalytic activity was attributable to the reduced bandgap (Egap = 2.01 eV), unique morphology, high specific surface area (1099.89 m2/g), and intimate contact between ZIF67 and NiMoO4, which facilitated the establishment of the Z-scheme heterojunction. Active species trapping tests verified that •O2− and h+ were the primary species, supporting the proposed degradation mechanism. This work highlights a valid Z-scheme ZIF67/NiMoO4 heterojunction system for efficient carrier separation and, therefore, enhanced photocatalytic degradation of antibiotics. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of alkaline hydrogen evolution reaction (HER) hinders practical exploitation of water splitting. Catalysts, known as platinum single atoms (Pt‐SAs) anchored in Ni4Mo/Ni alloys on nickel foam (Pt SAs‐Ni4Mo/Ni@NF) with ultralow Pt mass loading (mPt = 0.3 wt.%) derived from self‐reconstruction, with boosted atomic utilization in alkaline HER are demonstrated. In situ characterizations confirm the leaching of Mo species during the self‐reconstruction of NiMoO4, which facilitates the anchoring of Pt‐SAs through the generation of atomic defects. Further, density functional theory (DFT) calculations indicate that the atomic defects can effectively capture Pt2+ in salt solution, aiding in the distribution of Pt‐SAs. Besides, theoretical results emphasize that Pt SAs‐Ni4Mo/Ni with unique Pt‐Ni interaction can accelerate the desorption of hydroxides in alkaline electrolytes during HER, as well as lower energy barriers for reaction steps. Pt SAs‐Ni4Mo/Ni@NF shows remarkable catalytic activity toward alkaline HER with a low overpotential of 17 mV (j = 10 mA cm−2), together with high atomic utilization of Pt (8.92 A mgPt−1 at 30 mV) and excellent durability. This work not only provides a scalable preparation for efficient and robust low‐Pt catalysts but also establishes in‐depth understanding of the synergistic interaction between Pt SAs and Ni‐Mo alloys in alkaline HER, which is likely to accelerate the development of water‐splitting technique. [ABSTRACT FROM AUTHOR]

In this work, a chemically stable NiMoO4/NRGO nanocomposite was prepared via a facile hydrothermal method. The flower‐like structure of NiMoO4 (NMO) nanoparticles is randomly distributed on the surface of nitrogen‐doped reduced graphene oxide (NRGO) sheets, as observed in FESEM images. Compared to related reports, the NMO/NRGO (II) nanocomposite exhibits an excellent high surface area of 368.9 m2 g−1 and a mesoporous nature, as shown in N₂ adsorption‐desorption isotherms. The specific capacitance of the NMO/NRGO (II) electrode is 721 F g−1 at 1 A g−1 using a 6 M KOH electrolyte, retaining 91.2 % of its initial value after 5000 cycles. Electrochemical impedance spectroscopy (EIS) reveals that the electrode has a lower charge‐transfer resistance, indicative of good electrochemical behavior. An asymmetric device consisting of NMO/NRGO (II) || activated carbon (AC) electrodes exhibits a high energy density of 49.1 Wh kg−1 at 524.4 W kg−1 within a voltage range of 1.4 V, retaining 89 % of its initial capacitance after 5000 cycles, demonstrating good cyclic durability. These results suggest that the NMO/NRGO (II) electrode is a promising active material for supercapacitor devices. [ABSTRACT FROM AUTHOR]

Self-reconstruction of catalysts during oxygen evolution reaction (OER) is crucial for the development of energy conversion technologies. However, the relationship between the specific atomic structure of pre-catalysts and their electrocatalytic behavior after reconstruction via dual-ion leaching has not been extensively researched. In this work, we design a highly effective non-noble metal OER catalyst with heterointerface through continuous self-reconstruction of Co2(OH)3Cl@NiMoO4 as pre-catalyst by a straightforward dual-ion (i.e. MoO42− and Cl−) leaching. In-situ Raman and in-situ Fourier transform infrared (FT-IR) spectroscopy have precisely identified the progressive phase transformation of the pre-catalyst during self-reconstruction, which results in a stable heterojunction of CoOOH and NiOOH (CoOOH@NiOOH). Further calculations based on density functional theory (DFT) of CoOOH@NiOOH evident that more electrons will be aggregated in the Fermi level of Co. Notably, Gibbs free energy (ΔG) for different OER steps of CoOOH@NiOOH exhibit lower energy costs of all intermediates, implying the well catalytic properties. Ultimately, the catalyst derived from dual-ion leaching displays outstanding OER performance, characterized by an overpotential of 275 mV at a current density of 10 mA·cm−2 and exceptional stability over 12 h reaction. This work successfully paves a way of finding high-performance OER catalysts based on non-noble metal through dual-ion leaching during self-reconstruction. [ABSTRACT FROM AUTHOR]

Exhausting carbon-based gases from building construction or comfortable household supplies have caused the main pollution gas species for the indoor air environment. Given the variety of indoor activities, many reports have been challenged to find room-temperature operational and harmless materials. Here, we report that the activating MoO vibration mode in Na,Sb doped-NiMoO4 micro-sized powder reveals the high response of CO and VOC, occupying multiple bonds at room temperature. We performed Na and Sb doping in the α-NiMoO4 crystal structure, such as introducing the Sb in Ni and interstitial doping of Na in around 4 Å of free space in the NiMoO4 crystal structure that manipulates the partial β-NiMoO4 phase. The Na,Sb-codoped NiMoO4 generates the higher MoO vibration mode from FT-IR measurement and enables carbon-based gas detection with 38 responses to CO and nearly 20 responses to VOC under 20 ppm of each analyte gases environment. Furthermore, the n-type gas sensing behavior of Na,Sb doped-NiMoO4 chemiresistor exhibits an immediate sensing response instead of a none-of response than intrinsic or single element doped NiMoO4. These results suggest that Na,Sb codoped-NiMoO4 is the applicable material for emergent warning against carbon-based gas exposure in the indoor environment. In addition, activating the electrochemical reaction site of MoO4–2 in NiMoO4 is tailorable by a simple doping process.

Development of highly active and selective electrocatalysts for the reduction of nitrate (NO3–) to ammonia is critical for the production of green ammonia. Herein, we designed and synthesized NiMoO4 nanocubes as an efficient electrocatalyst for nitrate reduction using deep eutectic solvents (DESs) as synthesis media. By constructing Mo and Ni dual-active sites, Mo facilitates NO3– adsorption/association, and Ni acts as an active hydrogen (*H) donating center. The amount and destination of *H can be regulated, which can effectively enhance the activity of the NO3– reduction to NH3 reaction (NO3–RR). The optimized sample possessed excellent NO3–RR activity. An NH3–N selectivity of up to 96.94% and a Faraday efficiency of up to 96.13% can be achieved at −0.4 V in a neutral solution. The catalytic NO3–RR mechanism was also investigated by density functional theory (DFT) calculations. This dual-active site electrocatalyst provides an alternative idea for the synthesis and application of high-performance NO3–RR catalysts. [ABSTRACT FROM AUTHOR]

Flexible wearable electronic skin (e-skin) has great potential in health monitoring, human–computer interaction, and other fields. However, traditional devices are often unable to maintain high sensitivity while achieving a wide detection range. In this work, inspired by biomimicry, we proposed a design based on mimosa flowers and developed a composite pressure sensing device (reduced graphene oxide (rGO)/NiMoO4@CMF). The strain layer of the sensor undergoes hydrothermal growth, allowing nickel molybdate (NiMoO4) to grow in situ on the surface of the carbon melamine foam (CMF). This enhances the substrate morphology, and rGO is then applied to increase the electrical conductivity. The devices prepared by this method have sensitivities of 19.3, 12.5, and 8.1 kPa–1 in the ranges of 0–12, 12–29, and 29–40 kPa, respectively. In addition, the sensor demonstrates a low detection limit (10 Pa), a fast response (160 ms), and a cycle retention rate of 86% after 5000 cycles. Based on these characteristics, the flexible sensor can detect strong human body movements in real time, such as finger bending, elbow movement, and knee bending. The study shows that this pressure sensor has broad application prospects in health monitoring. [ABSTRACT FROM AUTHOR]

This article successfully prepared porous NiMoO4 sheet-like structured nanomaterials deposited on carbon cloth using the freeze-drying method. The morphology and phase structure were characterized by SEM, TEM, and XRD, proving that the material is NiMoO4 porous nanosheets. The NiMoO4 porous nanosheets have a large specific surface area, which increases the reaction sites of the material, shortens the transmission distance of electrons and ions, accelerates the reaction rate, and thus improves the charge storage capacity. We conducted electrochemical performance tests on the material, and the test results showed that the specific capacity was 1683 F/g at a current density of 5 A/g. After 5000 cycles, the capacitance retention rate was 99.7%. We further assembled NiMoO4 porous nanosheets as positive electrodes and CNTs as negative electrodes to form solid-state asymmetric capacitor devices. At a current density of 15 A/g and a working window voltage of 1.6 V, the asymmetric device has an energy density of 70.8 Wh/Kg and a power density of 7000 W/Kg. After 10,000 cycles at a current density of 5 A/g, the device exhibits excellent cycling stability with a capacitance retention rate of 87.6%. This article provides a valuable reference for the development of electrode materials for capacitors. [ABSTRACT FROM AUTHOR]

Significant advances in the field of energy storage have enabled scientists to explore highly stable electro-active electrodes for high-performance supercapacitors. The present investigation describes the synthesis of well-ordered NiMoO4 nanowalls at 140 °C using hydrothermal synthesis, which was then grown directly on Ni foam with different reaction times. The resulting NiMoO4 nanowalls were utilized as electro-active electrodes for electrochemical supercapacitor applications. The reaction time was found to be a critical factor in achieving the ordered NiMoO4 nanowalls on the Ni foam, and at a reaction time of 12 h, the nanosheets self-organized into a nanowall-like morphology over the Ni foam. Pure NiMoO4 crystal phases with less surface imperfections were produced by the 12-hour reaction time, as demonstrated by the compositional, structural, and crystalline characteristics. As an electro-active electrode, the NiMoO4 electrode with a 12-hour reaction time showed the highest specific capacitance of 357.6 Fg−1 at 0.01 Vs−1 compared to NiMoO4 electrodes with reaction times of 6h (53.06 Fg-1 at 0.01 Vs−1) and 20h (55.4 Fg-1 at 0.01 Vs−1). The NiMoO4 electrode also demonstrated exceptional stability in an alkaline electrolyte, exhibiting less deterioration in multicycles CV after 100 repeated cycles. The excellent electrochemical properties of the NiMoO4 electrode are attributed to its unique ordered nanowall structure, which improves surface area and electrical conduction, accelerating fast redox reactions. These properties make it a promising material for use in pseudocapacitors, with implications for high-performance energy storage solutions in industrial sectors.

CuMnO 2 /XMoO 4 (X=Ni, Co, Fe) is a novel high-efficiency photocatalyst, which was synthesized by electrostatic self-assembly method. Under visible light irradiation, by comparing with other eighth main group metals (Fe, Co), it was found by experimental study that adding 30 mg of CuMnO 2 to 100 mg of NiMoO 4 (CuMnO 2 /NiMoO 4 -30%), it has the best hydrogen evolution effect up to 300 μ mol, which is 1.49 and 2.88 times more effective than CuMnO 2 /CoMoO 4 and CuMnO 2 /FeMoO 4 respectively. Meanwhile, the hydrogen evolution yield of CuMnO 2 /NiMoO 4 was about 4 times that of CuMnO 2 and NiMoO 4. The photoelectrochemical and time-resolved fluorescence experiments confirmed the excellent charge separation efficiency of the composite catalyst, and the linear voltammetry curve showed that the composite catalyst had the characteristics of high current response. When CuMnO 2 is loaded on NiMoO 4 , CuMnO 2 /NiMoO 4 exhibits excellent photocatalytic activity due to the formation of Type I heterojunction, which promote charge transfer and effectively improve the separation of electrons and holes. This experiment provides a simple and feasible idea for the study of composite catalysts with high catalytic activity. • The heterojunction between CuMnO 2 and NiMoO 4 has good stability. • Dispersion of CuMnO 2 on NiMoO 4 is important for the HER activity. • Discussion on electron transfer path and hydrogen evolution mechanism. [ABSTRACT FROM AUTHOR]

One-dimensional NiMoO4 nanofibers were successfully prepared by electrospinning and high-temperature calcination. The supercapacitor performance tests were conducted on the prepared materials in a three-electrode system, and it was found that the calcination temperature during the preparation of the fibers seriously affects the final morphology and electrochemical performance of the obtained samples. The sample with a calcination temperature of 500 °C has better performance, its specific capacitance can reach 1947 F g−1, and the retention rate is 82.35% after 3000 cycles of constant current charging–discharging. The improvement of electrochemical performance is primarily on account of the unique one-dimensional nanostructure of the material, which can both enhance the charge transfer efficiency and effectively increase the speed of electrolyte ion diffusion. [ABSTRACT FROM AUTHOR]

Micro/nano-heterostructure with subtle structural design is an effective strategy to reduce the self-aggregation of 2D structure and maintain a large specific surface area to achieve high-performance supercapacitors. Herein, we report a rationally designed micro/nano-heterostructure of complex ternary transition metal oxides (TMOs) by a two-step hydrothermal method. Microflake-assembled island-like CuCo2O4 frameworks and secondary inserted units of NiMoO4 nanosheets endow CuCo2O4/NiMoO4 composites with desired micro/nanostructure features. Three-dimensional architectures constructed from CuCo2O4 microflakes offer a robust skeleton to endure structural change during cycling and provide efficient and rapid pathways for ion and electron transport. Two-dimensional NiMoO4 nanosheets possess numerous active sites and multi-access ion paths. Benefiting from above-mentioned advantages, the CuCo2O4/NiMoO4 heterostructures exhibit superior pseudocapacitive performance with a high specific capacitance of 2350 F/g at 1 A/g as well as an excellent cycling stability of 91.5% over 5000 cycles. A solid-state asymmetric supercapacitor based on the CuCo2O4/NiMoO4 electrode as a positive electrode and activated carbon as a negative electrode achieves a high energy density of 51.7 Wh/kg at a power density of 853.7 W/kg. These results indicate that the hybrid micro/nanostructured TMOs will be promising for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

The great promise of the combination of urea oxidation reaction (UOR) with hydrogen evolution reaction (HER) to simultaneously achieve wastewater treatment and hydrogen production calls for the rational design of high‐performance electrocatalysts. Herein, the reconstruction with the formation of Ni2P and Mo2O72− on the surface can largely enhance the alkaline HER activity of P‐NiMoO4 by on‐site electrochemical activation strategy. Systematic experimental results indicate that the reconstruction process enables the exposure of additional Ni sites and the adjustment of hydrogen adsorption to facilitate HER kinetics. Ultimately, a highly efficient alkaline HER electrode with low overpotential of −48.9 mV for 10 mA cm−2 is achieved. More importantly, a UOR electrolyzer assembled with A‐P‐NiMoO4 as the cathode and P‐NiMoO4 as the anode exhibits impressive performance with a small cell voltage of 1.363 V for 10 mA cm−2. The application of the fabricated electrodes in a practical cell driven by a commercial dry battery (1.5 V) demonstrates efficient and stable hydrogen production, making the developed strategy promising for the rational design of highly active electrocatalysts for green hydrogen production. [ABSTRACT FROM AUTHOR]

Promoting the separation of electron and hole plays an important role in photocatalytic hydrogen production. However, single semiconductor materials cannot fully realize their potential due to the rapid recombination of photogenerated carriers. Therefore, in this experiment, a new photocatalyst ZnIn 2 S 4 /NiMoO 4 was prepared by using an electrostatic self-assembly method, which greatly improved the electron-hole recombination phenomenon. After 5 h reaction under visible light irradiation, ZIS/NMO-3 composite catalyst prepared in ethanol showed the best photocatalytic activity, and the hydrogen evolution capacity reached 173.09 μmol. The hydrogen evolution capacity of ZIS/NMO-3 was 2.47 and 25.83 times that of short rod-like NiMoO 4 and microflower-like spherical ZnIn 2 S 4 , respectively. Through some physical characterization and electrochemical experiments, it can be seen that NiMoO 4 and ZnIn 2 S 4 have good composability. Meanwhile, the composite catalyst ZnIn 2 S 4 /NiMoO 4 -3 has high current response characteristics. It can be seen from the fluorescence emission spectra that the composite catalyst presents the lowest peak value, which indicates that ZIS/NMO-3 can effectively inhibit the recombination of photogenerated electrons and holes. When ZnIn 2 S 4 is loaded on NiMoO 4 , the separation of photogenerated carrier will be accelerated due to the formation of heterojunction, thus improving the photocatalytic activity. At the same time, the large specific surface area will also provide more abundant active sites for the composite catalyst, which provides a good condition for photocatalytic hydrogen production. This work provides an efficient, uncomplicated and feasible method for the synthesis of ZIS/NMO-3 composite catalyst with excellent properties. • The heterojunction between ZnIn 2 S 4 and NiMoO 4 has good stability. • Dispersion of ZnIn 2 S 4 on NiMoO 4 is important for the HER activity. • Discussion on electron transfer path and hydrogen evolution mechanism. • High-efficiency hydrogen evolution is realized through ZnIn 2 S 4 /NiMoO 4 heterojunction. [ABSTRACT FROM AUTHOR]

Abstract Electrocatalytic water splitting is a viable technique for generating hydrogen but is precluded from the sluggish kinetics of oxygen evolution reactions (OER). Small molecule oxidation reactions with lower working potentials, such as methanol oxidation reactions, are good alternatives to OER with faster kinetics. However, the typically employed Ni-based electrocatalysts have poor activity and stability. Herein, a novel three-dimensional (3D)-networking Mo-doped Ni(OH)2 with ultralow Ni–Ni coordination is synthesized, which exhibits a high MOR activity of 100 mA cm−2 at 1.39 V, delivering 28 mV dec−1 for the Tafel slope. Meanwhile, hydrogen evolution with value-added formate co-generation is boosted with a current density of more than 500 mA cm−2 at a cell voltage of 2.00 V for 50 h, showing excellent stability in an industrial alkaline concentration (6 M KOH). Mechanistic studies based on density functional theory and X-ray absorption spectroscopy showed that the improved performance is mainly attributed to the ultralow Ni–Ni coordination, 3D-networking structures and Mo dopants, which improve the catalytic activity, increase the active site density and strengthen the Ni(OH)2 3D-networking structures, respectively. This study paves a new way for designing electrocatalysts with enhanced activity and durability for industrial energy-saving hydrogen production.

• Bi-MOF sacrificial template to construct oxygen-deficient α-Bi 2 O 3 nanobelt. • More exposed active sites and promoted electron transfer guarantee the high capacity. • High specific capacity and long-term cycle stability were achieved for Bi 2 O 3 nanobelt. • High energy density was delivered for assembled Bi 2 O 3 //NiMoO 4 battery device. Bi 2 O 3 has been recognized as a promising anode of aqueous secondary battery because of the high capacity, but the application is greatly hindered by the poor conductivity and limited actual capacity. Herein, for the first time, one dimensional (1D) α-Bi 2 O 3 nanobelt is fabricated via alkali etching strategy using rod-shaped Bi-MOF (CAU-17) as the self-sacrificial template. Specifically, high-crystalline and oxygen-deficient α-Bi 2 O 3 nanobelt with length and width of 6 μm and 300 nm are identified. The electrochemical results demonstrate the high specific capacity (247 mAh g−1@1 A g−1) and acceptable stability of α-Bi 2 O 3 nanobelt. Such superior capacity is derived from the exposed electrochemical active sites, fast charge transfer and efficient ion diffusion in 1D high-crystalline and oxygen-vacancies enriched structure. The assembled Ni-Bi battery displays high capacity (78.3 mAh g−1) and high energy density of 100.2 Wh kg−1 (at power density of 2829.8 W kg−1). Our work provides rational guidance for architecting 1D high-capacitive electrodes for aqueous rechargeable alkaline battery. In this work, MOF-derived 1D oxygen-deficient α-Bi 2 O 3 nanobelt with more exposed electrochemical active sites are synthesized via controllable alkali-etching strategy. Satisfying specific capacity and energy density are delivered on account of the more exposed active sites, promoted electrolyte diffusion and accelerated electron transfer. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, we innovatively employed low-temperature phosphorization technology to successfully incorporate P doping into NiMoO 4 nanorods. Subsequently, utilizing the electrodeposition method with a solution rich in Ni²⁺ and Fe³⁺ as the electrolyte, we delicately tuned the process to identify the optimal deposition time, achieving a uniform coating of NiFe LDH on the surface of the P-doped NiMoO 4 nanorods. This led to the construction of a three-dimensional core-shell structured NiFe LDH@P-NiMoO 4 composite material. To validate the performance of this composite, we conducted thorough structural characterization and electrochemical oxygen evolution reaction (OER) performance tests. The experimental results revealed that in a 1 M KOH electrolyte environment, when the current density reached 100 mA cm⁻², the composite exhibited exceptionally superior OER performance, with an overpotential of merely 267 mV and a Tafel slope as low as 93 mV dec⁻¹, firmly demonstrating its remarkable catalytic efficiency. Furthermore, the composite displayed good stability and durability during prolonged testing, providing a solid foundation for its practical application. In summary, this work not only paves a new way for the preparation of high-performance non-precious metal OER electrocatalysts but also provides robust support for the realization of efficient and stable energy conversion and storage technologies. • NiFe double hydroxide coating over phosphorus-modified NiMoO 4 nanorod are fabricated. • The doping of P element and core-shell structure effectively improve the performance of OER. • The composite exhibited superior OER performance. • The composite displayed good stability and durability. [ABSTRACT FROM AUTHOR]

Globally, the hidden contaminants like microplastics (MPs) combined with other harmful substances have agglomerated in rivers and oceans that pose a threat to human health. Thus, evaluating the toxicity of MPs separately and in combination with other pollutants must be done quickly and precisely. This work reports the synthesis of porous NiMoO 4 nanotubes (NTs) from the transformation of MoO 3 nanorods (NRs) via two steps hydrothermal methods for the effective detection of polyvinyl chloride (PVC) MPs. Transformation of MoO 3 NRs to porous NiMoO 4 NTs was comprehensively deduced by evaluating the crystalline, structural, compositional and morphological properties. The hydrophobic nature of MoO 3 NRs and porous NiMoO 4 NTs was proven experimentally and also by DFT calculations. The electrochemical detection of PVC MPs by NiMoO 4 NTs was investigated by the CV and EIS measurements. Porous NiMoO 4 NTs based electrode expressed the good detection towards PVC MPs with a reasonable sensitivity of ∼1.43 × 10−4 μA/ppm.cm2, a low LOD of ∼18 ppm and R 2 = ∼0.9781. EIS results revealed that porous NiMoO 4 NTs electrode enabled to deliver sensing response at very low concentration of PVC MPs. Due to their easy interaction with hydrophobic PVC MPs, the hydrophobic NiMoO 4 NTs controlled the sensing nature of the material and improved the electrochemical detection at the MP-NiMiO 4 NTs interface. [Display omitted] • Porous NiMoO 4 nanotubes (NTs) are synthesized by the transformation of MoO 3 nanorods (NRs) via two steps hydrothermal methods. • Porous NiMoO 4 NTs are utilized as electrode for the effective detection of polyvinyl chloride (PVC) MPs. • DFT calculations were done to establish the hydrophobic nature of MoO 3 NRs and NiMoO 4 NTs. • Porous NiMoO 4 NTs based electrode shows the good detection towards PVC MPs via cyclicvoltammetry and electrochemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Supercapacitors have emerged as one of the promising energy storage systems owing to their rapid charge/discharge capability, long-term cycling stability, and high power density. The application of core-shell nanostructures for supercapacitors is one of the effective strategies to achieve a high specific surface area for abundant reaction sites and good electrical conductivity for fast charge transfer, hence improving the performance of supercapacitors. Particularly, the use of NiMoO4 for the core-shell structure has drawn great attention due to its outstanding advantages, such as its natural abundance, low material cost, superior electrochemical performance, and wide electrochemical potential window in cyclic voltammetry. In this context, this review comprehensively covers the recent progress of the core-shell nanostructures based on the NiMoO4-composite materials, which find applications in supercapacitors. The composite materials that incorporate metal oxides such as NiMoO4, metal hydroxides, metal chalcogenides, carbon materials, and conductive polymers are discussed in detail for such core-shell nanostructures with the aim of understanding how the adopted materials and the relevant morphology govern the electrochemical features for supercapacitors. Finally, the existing challenges in current technologies for supercapacitors are discussed, while possible future directions in developing the NiMoO4-composite-based core-shell nanostructures are proposed for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Transition−metal−based materials show great promise for energy conversion and storage due to their excellent chemical properties, low cost, and excellent natural properties. In this paper, through simple strategies such as classical electrospinning, air calcination, and the one−step hydrothermal method, a large area of Ni(OH)2 nanosheets were grown on NiMoO4 nanofibers, forming NiMoO4@Ni(OH)2 nanofibers. The one−dimensional nanostructure was distributed with loose nanosheets, and this beneficial morphology made charge−transfer and diffusion more rapid, so the newly developed material showed good capacitance and conductivity. Under the most suitable experimental conditions, the optimal electrode exhibited the highest specific capacitance (1293 F/g at 1 A/g) and considerable rate capability (56.8% at 10 A/g) under typical test conditions. Most interestingly, the corresponding asymmetrical capacitors exhibited excellent electrochemical cycle stability, maintaining 77% of the original capacitance. NiMoO4@Ni(OH)2 nanofibers were verified to be simple to prepare and to have good performances as energy−storage devices within this experiment. [ABSTRACT FROM AUTHOR]

Highlights: A novel Ni(OH)2-based catalyst with ultralow Ni–Ni coordination is produced, exhibiting high activity (100 mA cm−2 at 1.39 V for methanol oxidation reactions) and outstanding stability in an industrial concentration electrolyte (over 500 mA cm−2 in 6 M KOH). Mechanistic studies show that the improved kinetics and durability are primarily due to ultralow Ni–Ni coordination, 3D-networking structures and the Mo dopant. Electrocatalytic water splitting is a viable technique for generating hydrogen but is precluded from the sluggish kinetics of oxygen evolution reactions (OER). Small molecule oxidation reactions with lower working potentials, such as methanol oxidation reactions, are good alternatives to OER with faster kinetics. However, the typically employed Ni-based electrocatalysts have poor activity and stability. Herein, a novel three-dimensional (3D)-networking Mo-doped Ni(OH)2 with ultralow Ni–Ni coordination is synthesized, which exhibits a high MOR activity of 100 mA cm−2 at 1.39 V, delivering 28 mV dec−1 for the Tafel slope. Meanwhile, hydrogen evolution with value-added formate co-generation is boosted with a current density of more than 500 mA cm−2 at a cell voltage of 2.00 V for 50 h, showing excellent stability in an industrial alkaline concentration (6 M KOH). Mechanistic studies based on density functional theory and X-ray absorption spectroscopy showed that the improved performance is mainly attributed to the ultralow Ni–Ni coordination, 3D-networking structures and Mo dopants, which improve the catalytic activity, increase the active site density and strengthen the Ni(OH)2 3D-networking structures, respectively. This study paves a new way for designing electrocatalysts with enhanced activity and durability for industrial energy-saving hydrogen production. [ABSTRACT FROM AUTHOR]

Synthesis of a class of Lx‐β‐NiMoO4 (L = None, Al, V, Fe, Co) nanocomposites by a facile one‐step solid‐state route at 700, 800, and 900 °C for 8 h is introduced in the present study. The physical and electrochemical properties of the fabricated compounds are studied by X‐ray powder diffraction (XRPD), field‐emission scanning electron microscope, energy‐dispersive X‐ray spectroscopy, Fourier‐transform infrared spectroscopy, UV‐vis, vibrating sampling magnetometer (VSM), and cyclic voltammetry (CV) analyses. XRPD patterns associated with Rietveld analysis data performed by the FullProf program confirm that the as‐prepared samples are crystallized in the β polymorph monoclinic NiMoO4 crystal system. The magnetic property investigated by VSM analysis data shows that the fabricated samples have ferromagnetic behavior. It is found that the highest Ms value is obtained when Fe3+ is doped into the NiMoO4 crystal system. The smallest direct band gap energy (Eg) is obtained for V‐doped NiMoO4 nanocomposite. The electrochemical property of the prepared NiMoO4 nanocomposites is studied by CV analysis. The data confirm that NiMoO4 can be used in energy storage applications. An impedance spectroscopy plot of NiMoO4 reveals that the Z value is about 30 Ω cm−2. The slope of the curve is near to 90° representing a good capacitance behavior of NiMoO4. [ABSTRACT FROM AUTHOR]

Based on the measured strategy of photo-assisted promotion of the battery performance of LOBs, we designed a Co 3 O 4 @NiMoO 4 cathode with a core–shell structure. At a high current density of 1.0 mA cm−2 and a capacity of 0.5 mAh cm−2, Co 3 O 4 @NiMoO 4 , as the cathode of the photo-assisted LOBs, has the first charge and discharge overpotential of 1.01 V and a cycle life of 164 times with illumination，which is obviously better than without illumination. [Display omitted] • Co 3 O 4 @NiMoO 4 with core–shell structure was synthesized by a two-step hydrothermal method. • Co 3 O 4 @NiMoO 4 shows good optical and electrochemical properties, due to the construction of core–shell structures. • The decomposition of Li 2 O 2 during the discharge process was facilitated by photo assistance. • Co 3 O 4 @NiMoO 4 with illumination shows better cycling stability and rate capability at high current density. Lithium-oxygen batteries (LOBs) are regarded as the most potential energy storage systems for the next generation due to their exceptionally high theoretical energy density. However, the discharge product (Li 2 O 2) results in significant overpotentials during charging and discharging, which severely limits the application of LOBs. In this work, Co 3 O 4 @NiMoO 4 core–shell structures were prepared by a secondary hydrothermal method and used as a photo-assisted LOB cathode. The core–shell structure not only enhances light absorption and conductivity, facilitating the separation of photoelectrons and holes, but also provides additional reaction sites for the OER and ORR. It has a low charging/discharging overpotential of 1.01 V and can operate stably for 164 cycles (at the current density of 1.0 mA cm−2 and the capacity of 0.5 mAh cm−2) with good multiplicative performance with illumination. This paper is an effective and valuable reference for the subsequent development of cathode catalysts for photo-assisted LOBs. [ABSTRACT FROM AUTHOR]

In this paper, different foreign ions M (M=Co, Cu and Fe) are introduced into this NiMoO 4 material by hydrothermal and impregnation methods. Their electrocatalytic properties were investigated in different electrolytes, such as urea, pure water and seawater. [Display omitted] • Different foreign ions M (M = Co, Cu and Fe) are introduced into this NiMoO 4 material by hydrothermal and impregnation methods. • Co-NiMoO 4 @NF presented excellent urea oxidation reaction performance (1.32V @ 10 mA cm−2). • Fe3+-NiMoO 4 @NF presented excellent oxygen evolution reaction performance (overpotential 260 mV @ 10 mA cm−2). Electrocatalytic splitting of urea or seawater for hydrogen production has become one of the most promising methods. In this paper, different foreign ions M (M = Co, Cu and Fe) are introduced into this NiMoO 4 material by hydrothermal and impregnation methods. Their electrocatalytic properties were investigated in different electrolytes, such as urea, pure water and seawater. What is noteworthy is that the Co-NiMoO 4 /NF electrode exhibited superior urea oxidation properties (1.32 V @ 10 mA cm−2). The different reaction mechanisms result in the superior water oxidation performance of this Fe3+-NiMoO 4 /NF material. What is noteworthy is that the durability of the material needs to be improved. The promoted performance is attributed to rapid electron transfer and improved electrical conductivity. Density functional theory (DFT) also shows that this Fe-NiMoO 4 /NF electrode presents optimal water adsorption energy and improved electrical conductivity, thus improving the catalytic activity of the material because of introduction of Fe. The work provides novel views for the design of environmentally friendly and inexpensive multifunctional catalysts for urea, freshwater and seawater splitting reaction. [ABSTRACT FROM AUTHOR]

• The morphology of the catalyst increases the contact area and active sites. • NiMoO 4 contains Ni Mo element, which suppresses the photo corrosion of ZnCdS. • Constructed an S-scheme heterojunction, which enhances the ability of the catalyst. • The mechanism of S-scheme heterojunction was explained by in situ characterization. • The work function was calculated using DFT, and the reaction mechanism was verified. In the field of photocatalysis, when it comes to performance, ZnCdS can be said to be second to none, as its suitable bandgap structure and electron rich properties are highly sought after by most researchers. However, how to solve the severe photo corrosion and recombination of photo generated carriers has become a huge challenge that needs to be addressed. Constructing heterojunctions is an effective method to solve this problem. In this work, ZnCdS and NiMoO 4 S-scheme heterojunctions were first constructed. This catalyst tightly combines two elements together, and the synergistic effect of Ni and Mo elements in NiMoO 4 effectively suppresses the photo corrosion of ZnCdS and greatly improves its performance. The electron rich nature of ZnCdS causes its own electrons to transfer to NiMoO 4 , which in turn promotes the hydrogen evolution reaction of NiMoO 4. In fact, the built-in electric field between catalyst interfaces provides power for electron transfer. It is worth noting that studying in situ XPS and density functional theory calculations has provided a deeper understanding of charge dynamics. This work provides ideas for improving charge transfer and designing high-performance catalysts to address energy issues. [ABSTRACT FROM AUTHOR]

Based on the structural characteristics of bimetallic phosphates, the rod‐like NiCoP/NiMoO4 heterojunction composite catalyst is successfully synthesized by hydrothermal method, which realizes the rapid transfer of photogenerated carriers across the heterojunction interface, thereby improving the performance of photocatalytic decomposition of water to produce hydrogen. Through photocatalytic experiments, the hydrogen evolution rate of the NiCoP/NiMoO4 is 61.4 μmol h−1, which is 2.93 times that of pure NiMoO4. Further study on the catalyst shows that this structure could greatly improve the utilization rate of sensitizer and hole sacrifice agent in the dye sensitization system, and the rate of photon‐generated carrier separation and transfer is significantly improved to achieve a good hydrogen evolution effect. [ABSTRACT FROM AUTHOR]

Different amounts of Fe2O3-coated NiMoO4/NiO composites were prepared by solvothermal method following with annealing process. The as-prepared NiMoO4/NiO@Fe2O3 composite exhibits a reversible specific capacity of 1250 mAh g−1 after 150 cycles at a current density of 100 mA g−1 as anode for lithium-ion batteries. It exhibits efficient long-term electrochemical performance and maintains the capacity at about 750 mAh g−1 at a high current density of 500 mA g−1 after 200 cycles. The good electrochemical performance of the NiMoO4/NiO@Fe2O3 composite may be due to its smaller size and the Fe2O3 coating which can restrain its volume collapse during the charge–discharge cycle. This work could provide a promising strategy for enhancing the performance of molybdate-based composite materials for practical application in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D core-shell structure of ZnFe 2 O 4 @NiMoO 4 NSAs is prepared by hydrothermal route. • Controlled hydrothermal route is employed for the preparation of NiMoO 4 shell. • The ZFO@NMO@rGO-NF electrode is suitable for high performance SCs applications. • MOFs derived 3D hollow nanocgaes is fabricated and employed as negative electrode. • An ASC device is sandwiched to appraise its potential applicability. Tailoring hierarchical hybrid core-shell electrodes with impartial microstructural features and excellent electroactive constituents is crucial for the design of high-performance supercapacitors (SCs). Herein, for the first time, we fabricate uniformly aligned porous ZnFe 2 O 4 (ZFO) nanosheet arrays onto reduced graphene oxide-garnished conductive Ni foam (rGO-NF) substrates and subsequently embellish the first layer of ZFO nanosheets with morphology-controlled secondary NiMoO 4 nanosheets to achieve a hierarchical 3D core-shell structure of ZnFe 2 O 4 @NiMoO 4 nanosheet arrays (NSAs) onto rGO-NF for SC applications. Improving the synergistic effect of the core-shell nanoarchitecture with a conductive rGO-NF substrate, the hierarchical 3D ZFO@NMO NSAs tend to have superb electronic conductivity, tailoribility, effective nanoporous channels, and appropriate roadways for rapid ion/electron transfer, which are required for rapid reversible redox reactions, thus reflecting the excellent electrochemical features, including the excellent specific capacitance, good rate performance, and prolonged cyclic performance of the three electrode assemblies for SCs. An asymmetric supercapacitor (ASC) device composed of ZFO@NMO NSAs@rGO-NF as the cathode and MOF-derived hollow porous carbon (MDHPC) as the anode exhibits a high energy density of 58.6 Wh kg-1 at a power density of 799 W kg-1 with prolonged cyclic durability (89.6 % after 7000 cycles), thus indicating its potential applicability towards advanced hybrid SCs. [ABSTRACT FROM AUTHOR]

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Efficient photoelectrochemical (PEC) water splitting systems in photoelectrodes are primarily challenged by electron-hole pair recombination. Constructing a heterostructure is an effective strategy to overcome this issue and to enhance PEC efficiency. In this study, we integrated NiMoO 4 , known for its proper electrocatalytic conductivity, into a BiVO 4 /Sn-doped WO 3 heterojunction using solution-based hydrothermal and spin-coating methods, forming an innovative double heterojunction concept. The resulting NiMoO 4 /BiVO 4 /Sn:WO 3 triple-layer heterojunction photoanode exhibits a photocurrent density of 2.06 mA cm -2 in a potassium borate buffer (KBi) electrolyte at 1.23 V vs RHE, outperforming the bilayer BiVO 4 /Sn:WO 3 heterojunction (1.45 mA cm -2 ) and Sn:WO 3 photoanodes (0.55 mA cm -2 ) by approximately 1.4 and 3.7 times, respectively. Remarkably, the NiMoO 4 /BiVO 4 /Sn:WO 3 double heterojunction photoanode exhibits notable stability, showing only an approximate 30% reduction in initial photocurrent density after 10 h of measurement in the KBi electrolyte without a hole scavenger. This stability is attributed to the excellent corrosion resistance of the thin NiMoO 4 layer, effectively protecting the bilayer BiVO 4 /Sn:WO 3 heterojunction photoanode from photocorrosion. Our findings show how this novel double heterojunction, established through simple and cost-effective solution-based methods, offers a promising approach to enhancing PEC water splitting applications.

[Display omitted] It is a great challenge to design electrode materials with good stability and high specific capacitance for supercapacitors. Herein, a three-dimensional (3D) hydrangea-like NiMoO 4 micro-architecture with Ag nanoparticles anchored on the surface has been designed by adding EDTA-2Na, which was assembled with reduced graphene oxide (rGO) and named as NiMoO 4 -Ag/rGO composite. Benefiting from the synergetic contributions of structural and componential properties, NiMoO 4 -Ag/rGO composite exhibits a high specific capacitance of 566.4 C g−1 at 1 A g−1, and great cycling performance with 90.5% capacitance retention after 1000 cycles at 10 A g−1. The NiMoO 4 -Ag/rGO electrode shows an enhanced cycling stability due to the two-dimensional towards two-dimensional (2D-2D) interface coupling between rGO and NiMoO 4 nanosheets, and the stable 3D hydrangea-like micro-architecture. Moreover, NiMoO 4 -Ag/rGO with 5–15 nm pore structure and enhanced conductivity exhibits improved charge transfer and ions diffusion. Besides, NiMoO 4 -Ag/rGO//AC capacitor displays an outstanding energy density of 40.98 Wh kg−1 at 800 kW kg−1, and an excellent cycling performance with 73.3% capacitance retention at 10 A g−1 after 8000 cycles. The synthesis of NiMoO 4 -Ag/rGO composite can provide an effective strategy to solve the poor electrochemical stability and slow electron/ion transfer of NiMoO 4 material as supercapacitors electrode. [ABSTRACT FROM AUTHOR]

Heteroatom doping is one of the most promising strategies toward regulating intrinsically sluggish electronic conductivity and kinetic reaction of transition metal oxides for enhancing their lithium storage. Herein, we designed phosphorus-doped NiMoO4 nanorods (P-NiMoO4) by using a facile hydrothermal method and subsequent low-temperature phosphorization treatment. Phosphorus doping played an indispensable role in significantly improving electronic conductivity and the Li+ diffusion kinetics of NiMoO4 materials. Experimental investigation and density functional theory calculation demonstrated that phosphorus doping can expand the interplanar spacing and alter electronic structures of NiMoO4 nanorods. Meanwhile, the introduced phosphorus dopant can generate some oxygen vacancies on the surface of NiMoO4, which can accelerate Li+ diffusion kinetics and provide more active site for lithium storage. As excepted, P-NiMoO4 electrode delivered a high specific capacity (1,130 mAh·g−1 at 100 mA·g−1 after 100 cycles), outstanding cycling durability (945 mAh·g−1 at 500 mA·g−1 over 200 cycles), and impressive rate performance (640 mAh·g−1 at 2,000 mA·g−1) for lithium ion batteries (LIBs). This work could provide a potential strategy for improving intrinsic conductivity of transition metal oxides as high-performance anodes for LIBs. [ABSTRACT FROM AUTHOR]

The facile design and fabrication of nanoarchitectured binary transition metal oxide electrode materials are essentially required for the advancement of highperformance supercapacitors (SCs). Herein, we prepared an oxygen-vacant NiMoO4 (Ov-NiMoO4) hollow sphere via a simple hydrothermal approach and subsequent heat treatment under an argon atmosphere. In particular, the oxygen vacancy is confirmed by using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman, and differential reflectance spectroscopy (DRS) UV-Vis spectra studies. Furthermore, the generation of the oxygen vacancy could enhance the electrical conductivity and improve Faradaic redox sites. Significantly, the Ov- NiMoO4 hollow sphere depicts a larger specific capacity (Csp) of 496 mA h g-1 at 1 A g-1than the bare-NiMoO4 (b-NiMoO4; 279 mA h g-1) thermally treated under air. Furthermore, the hybrid SC (HSC) is fabricated based on the Ov- NiMoO4//activated carbon, revealing a high specific capacitance (Cs) of 120 F g-1 and providing a large energy density (ED) of 37.49 W h kg-1 and power density (PD) of 36.61 kW kg-1. Moreover, the HSC shows considerable cyclic stability of ~91.14% over 20 000 cycles. The results divulge that the poor crystallinity and the introduction of oxygen vacancies play a vital role in enhancing the charge-storage capability of the materials. [ABSTRACT FROM AUTHOR]

Abstract—The synthesis of NiMoO4 hierarchical nanostructures using the hydrothermal method has been studied. The decomposition of NiMoO4·xH2O crystalline hydrate formed during the synthesis has been studied using synchronous thermal analysis upon heating in a stream of air and argon. According to X-ray diffraction as well as scanning and transmission electron microscopies, the proposed conditions allow one to synthesize single-phase nanosized (average CSR size of about 25 ± 2 nm) nickel(II) molybdate, which has a spinel-type monoclinic structure (space group C2/m) without impurity inclusions. [ABSTRACT FROM AUTHOR]

Supercapacitors have emerged as one of the promising energy storage systems owing to their rapid charge/discharge capability, long-term cycling stability, and high power density. The application of core-shell nanostructures for supercapacitors is one of the effective strategies to achieve a high specific surface area for abundant reaction sites and good electrical conductivity for fast charge transfer, hence improving the performance of supercapacitors. Particularly, the use of NiMoO4 for the core-shell structure has drawn great attention due to its outstanding advantages, such as its natural abundance, low material cost, superior electrochemical performance, and wide electrochemical potential window in cyclic voltammetry. In this context, this review comprehensively covers the recent progress of the core-shell nanostructures based on the NiMoO4-composite materials, which find applications in supercapacitors. The composite materials that incorporate metal oxides such as NiMoO4, metal hydroxides, metal chalcogenides, carbon materials, and conductive polymers are discussed in detail for such core-shell nanostructures with the aim of understanding how the adopted materials and the relevant morphology govern the electrochemical features for supercapacitors. Finally, the existing challenges in current technologies for supercapacitors are discussed, while possible future directions in developing the NiMoO4-composite-based core-shell nanostructures are proposed for high-performance supercapacitors.

• NiMoO 4 with different morphology has been synthesized through hydrothermal method. • NiMoO 4 with flower-like morphology possesses a high SC of 947 F g −1 at 1 Ag−1. • Both Ni2+/Ni3+ and Mo6+/Mo4+ are involved in the charge storage mechanism. • A hybrid supercapacitor rGO||NiMoO 4 can exhibit an energy density of 37.7 Wh kg−1. • The supercapacitor possesses 94 % capacitance retention after 6000 cycles. The electrochemical performance of electrode materials depends on various physicochemical properties like particle size, morphology, porosity, etc. of materials. Herewith, a facile surfactant assisted hydrothermal route using cetyltrimethylammonium bromide (CTAB) and hexamethylenetetramine (HMT) is used to successfully synthesize nanostructured nickel molybdate (NiMoO 4) with various morphologies. It is found that NiMoO 4 possesses different morphologies when synthesized by using these surfactants. With change in morphology, there is a significant increase in diffusion coefficient for sample synthesized with CTAB. It is interesting to note that NiMoO 4 synthesized by using CTAB exhibit a high specific capacitance of 947 F g −1 when cycled at 1 A g −1 in 1 M KOH solution as compared to that of 322 F g −1 (synthesized without CTAB), which can be ascribed to its flower-like shape with uniform porosity. Both Ni2+/Ni3+ and Mo6+/Mo4+ redox couples are involved in the capacitive characteristic of NiMoO 4 , as found from the XPS study. Additionally, a hybrid supercapacitor has been assembled using NiMoO 4 as positive electrode and reduced grapgene oxide (rGO) as negative electrode, which can exhibit 107 F g −1 with an operating voltage of 1.6 V with excellent cycling stability of maintaining 94 % capacitance retention after 6000 cycles in 1 M KOH solution. The hybrid supercapacitor can possess an energy density of 37.7 Wh kg−1 and a power density of 8 kW kg−1. Thus, this study enables the importance of tuning the morphology to enhance the capacitance property of transition metal oxide based electrode materials for supercapacitor applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing cost-effective and efficient electrocatalysts across a wide pH range poses a significant challenge in electrochemical water splitting for energy generation. Designing nanocomposites with well-tuned interfaces can significantly boost electrocatalytic performance. Here, we present an effective and durable g-C 3 N 4 (CN) modified NiMoO 4 (NM) electrocatalysts coated on nickel foam (NF) for maximizing electrochemical water splitting performance. We optimized the nanocomposite for effective hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity in acidic, neutral, and alkaline electrolytes by adjusting the weight ratio of the g-C 3 N 4. The NMCN-4/NF electrode exhibits the best electrochemical HER activity under alkaline and acidic conditions with lower overpotentials of −0.114 and −0.158 V, respectively, to achieve −10 mA cm−2. The highest HER activity was −127.3 mA cm−2 for the NMCN-4/NF under acidic conditions, which is 3.6 and 2.98 times greater than the pristine NM and CN-coated NF electrodes, respectively. Under an alkaline medium, the highest OER activity of the NMCN-4/NF was 152.9 mA cm−2, which is 4.07 and 2.75 folds higher than NM/NF and CN/NF electrodes, respectively. Besides, the NMCN-4 catalysts showed excellent photocatalytic degradation behavior on antibiotic pollutants with a percentage of 96.68%, which is 3.2 and 3.01% higher than pristine NM and CN catalysts, respectively. The NMCN-4 electro /photocatalysts exhibit an impressive balance of electro /photocatalytic efficiency and stability. [Display omitted] • The NiMoO 4 /g-C 3 N 4 nanocomposite was synthesized via a facile reflux heating method. • NMCN-4/NF exhibited the best electrochemical activity across a wide pH range. • NMCN-4/NF shows low HER overpotentials, −0.158 V and −0.114 V at −10 mA cm−2. • The synergistic effects of the NiMoO4 and g-C 3 N 4 phases boost photocatalytic activity. [ABSTRACT FROM AUTHOR]

The effectiveness of charge transfer and separation between bulk phase and the interface is crucial for evaluating the performance of photocatalysts. In this study, NiMoO 4 was employed to enhance the photocatalytic activity for hydrogen (H 2) evolution in twinned Cd 0.5 Zn 0.5 S (T-CZS) homojunctions comprising of wurtzite Cd 0.5 Zn 0.5 S (WZ-CZS) and zinc blende Cd 0.5 Zn 0.5 S (ZB-CZS) with alternating arrangements. The investigation reveals that the introduction of NiMoO 4 can lead to an increase of active sites for H 2 evolution, a prolongation of charge carrier lifetime, and a decrease of H 2 evolution overpotential. The H 2 production rate of 8 wt % NiMoO 4 /T-CZS reaches up to 71.2 mmol h−1 g−1, while its apparent quantum efficiency (AQY) is 8.23% at 400 nm. The enhanced activity can be attributed to the synergistic effects of homojunctions and heterojunctions in NiMoO 4 /T-CZS. According to the density functional theory (DFT), photoelectric response, and radical trapping experimental analysis, the charge transfer between WZ-CZS and ZB-CZS in T-CZS, as well as NiMoO 4 and T-CZS, both follow the S-scheme pathway under the influence of band bending, Coulombic force, and built-in electric field. This leads to an effective internal and interfacial charge separation in NiMoO 4 /T-CZS homo-heterojunctions, while maintaining their high reactivity. Additionally, the H 2 evolution activity of T-CZS can also be increased in different degrees by various metal molybdates (MMoO 4) including CoMoO 4 , Ag 2 MoO 4 , Bi 2 (MoO 4) 3 , BaMoO 4 , ZnMoO 4 , and CdMoO 4. The bulk and interfacial synergistic double S-scheme homo-heterojunctions in this study provide new insights for targeted solar driven H 2 evolution engineering. The NiMoO 4 /T-Cd 0.5 Zn 0.5 S system demonstrates a double S-scheme electron transfer pathway, leveraging the synergistic effects of interface S-scheme heterojunctions and bulk S-scheme homojunctions to facilitate efficient charge separation and transfer processes, thereby resulting in exceptional H 2 evolution performance. [Display omitted] • Twinned-Cd 0.5 Zn 0.5 S (T-CZS) consisting of zinc blende Cd 0.5 Zn 0.5 S and wurtzite Cd 0.5 Zn 0.5 S are successfully synthesized. • The photocatalytic H 2 evolution rate of NiMoO 4 /T-CZS with double S-scheme homo-heterojunctions reaches 71.2 mmol h−1 g−1. • MMoO 4 /T-CZS (M = Ni, Co, Ag, Bi, Ba, Zn, Cd) all exhibit excellent H 2 evolution performance. [ABSTRACT FROM AUTHOR]