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Supercapacitors (SCs) are considered promising energy storge systems because of their outstanding power density, fast charge and discharge rate and long-term cycling stability. The exploitation of cheap and efficient electrode materials is the key to improve the performance of supercapacitors. As the battery-type materials, transition metal phosphides (TMPs) possess high theoretical specific capacity, good electrical conductivity and superior structural stability, which have been extensively studied to be electrode materials for supercapacitors. In this review, we summarize the up-to-date progress on TMPs materials from diversified synthetic methods, diverse nanostructures and several prominent TMPs and their composites in application of supercapacitors. In the end, we also propose the remaining challenges toward the rational discovery and synthesis of high-performance TMP electrodes materials for energy storage.

The preparation, characterization, and catalytic activity of supported metal phosphides are reviewed. Reduction of metal compounds together with phosphate is a convenient method to prepare metal phosphides, but requires high temperature. Reduction with phosphite, hypophosphite, or phosphine and the plasma reduction of phosphate can be carried out at lower temperatures, which leads to smaller metal phosphide particles and more active catalysts. Organometallic routes allow the separate synthesis of metal phosphide nanoparticles, which have to be added to the support in a second step. LEED, STM, XPS, and DFT studies have shown that the surfaces of Ni 2 P reconstruct to P-rich surfaces. The investigation of metal phosphides as catalysts for hydrotreating reactions continues to be a topic of considerable research with recent advances realized in using bimetallic and noble metal phosphides to achieve high activities and tailored selectivities. Finally, hydrodeoxygenation catalysis over metal phosphides is a growing area of research given the need to develop catalysts for upgrading biomass to transportation fuels. Graphical Abstract

Two-dimensional (2D) materials have unique properties, such as large specific surface area, short carrier migration path, excellent light absorption efficiency, etc., which make them more advantageous than three-dimensional (3D) materials in the field of photocatalysts for water splitting. However, finding 2D materials with suitable band edge location, high carrier mobility and water adsorption capacity, simultaneously, which affect the activity of photocatalyst, is not easy. In this work, based on hybrid density functional calculation, the geometric structure, electronic and optical properties of boron phosphide (BP) are investigated. It shows that monolayer BP is a direct bandgap semiconductor with its bandgap 1.35 eV. Remarkably, this 2D material possesses extremely high electron mobility ~ 8.46 × 10 4  cm 2 V −1  s −1 and large difference in hole/electron mobilities, which can effectively hinder the recombination of electrons and holes. The band edge position of monolayer BP is favorable during water splitting in the pH range of 3–4. However, under the modulation of tensile strains + 6%, the bandgap of monolayer BP increases greatly, the photocatalytic pH range could almost cover the whole acid environment from 1 to 6. Optical obsorption spectrum also indicate its vital optical absorption capacity in UV–visible region. Meanwhile, monolayer BP has excellent abilities of adsorption of H 2 O molecules. These study suggest that 2D BP is a remarkably promising material to be utilized in photocatalyst for water splitting. Graphical Abstract

Tailoring the nanostructure/morphology and chemical composition is important to regulate the electronic configuration of electrocatalysts and thus enhance their performance for water and urea electrolysis. Herein, the nitrogen-doped carbon-decorated tricomponent metal phosphides of FeP 4 nanotube@Ni-Co-P nanocage (NC-FNCP) with unique nested hollow architectures are fabricated by a self-sacrifice template strategy. Benefiting from the multi-component synergy, the modification of nitrogen-doped carbon, and the modulation of nested porous hollow morphology, NC-FNCP facilitates rapid electron/mass transport in water and urea electrolysis. NC-FNCP-based anode shows low potentials of 248 mV and 1.37 V (vs. reversible hydrogen electrode) to attain 10 mA/cm 2 for oxygen evolution reaction (OER) and urea oxidation reaction (UOR), respectively. In addition, the overall urea electrolysis drives 10 mA/cm 2 at a comparatively low voltage of 1.52 V (vs. RHE) that is 110 mV lower than that of overall water electrolysis, as well as exhibits excellent stability over 20 h. This work strategizes a multi-shell-structured electrocatalyst with multi-compositions and explores its applications in a sustainable combination of hydrogen production and sewage remediation.

Supercapacitors have gained significant attention for energy storage due to their high power density and long cycle life. In this context, transition metal phosphides are particularly promising electrode materials for supercapacitors, owing to their high theoretical capacitance and rich redox chemistry. However, they require harsh synthesis conditions and prolonged processing time. Herein, a simple, one‐step electrodeposition method is presented for the synthesis of Fe‐incorporated CoP on Ni foam (NF), offering a rapid and scalable approach. By optimizing the precursor molar ratio of Fe:Co, the electrode material, Fe–CoP (10:20)/NF achieves a high specific capacitance of 920.3 F g−1 at 1 A g−1 with a high‐rate performance of 298.9 F g−1 at 50 A g−1 and retains 78.4% of its capacitance after 10 000 cycles at 30 A g−1. An asymmetric supercapacitor fabricated using Fe–CoP (10:20)/NF as the positive electrode and activated carbon as the negative electrode delivers an energy density of 16.37 Wh kg−1 at a power density of 799.98 W kg−1, with 73.8% capacitance retention after 2000 cycles at 5 A g−1. The enhanced electrochemical performance of CoP is attributed to the Fe incorporation, demonstrating an efficient strategy for advanced supercapacitor development. The electrodeposition method has been used to synthesize Fe–CoP deposited on nickel foam, resulting in excellent cycling stability and capacitance retention compared to CoP and FeP. Furthermore, a detailed charge storage mechanism, emphasizing the enhanced electrochemical performance has been discussed.

There is an increasingly urgent need to develop cost-effective electrocatalysts with high catalytic activity and stability as alternatives to the traditional Pt/C in catalysts in water electrolysis. In this study, microspheres composed of Mo-doped NiCoP nanoneedles supported on nickel foam were prepared to address this challenge. The results show that the nanoneedles provide sufficient active sites for efficient electron transfer; the small-sized effect and the micro-scale roughness enhance the entry of reactants and the release of hydrogen bubbles; the Mo doping effectively improves the electrocatalytic performance of NiCoP in alkaline media. The catalyst exhibits low hydrogen evolution overpotentials of 38.5 and 217.5 mV at a current density of 10 mA·cm −2 and high current density of 500 mA·cm −2 , respectively, and only 1.978 V is required to achieve a current density of 1000 mA·cm −2 for overall water splitting. Density functional theory (DFT) calculations show that the improved hydrogen evolution performance can be explained as a result of the Mo doping, which serves to reduce the interaction between NiCoP and intermediates, optimize the Gibbs free energy of hydrogen adsorption ( Δ G ∗ H ), and accelerate the desorption rate of *OH. This study provides a promising solution to the ongoing challenge of designing efficient electrocatalysts for high-current-density hydrogen production.

Understanding and manipulating synthetic progress for precisely controlling the components and defects of nanomaterials is an important and challenging task in materials synthesis and nanocatalysis. Metal phosphides (MPs) have been explored as cheap advanced materials in various catalytic fields. MP materials are usually synthesized through gas-solid phosphorization reaction in a trial-to-error manner, but their formation mechanism and the origin of controlled synthesis remain unclear. Here, we combine in situ thermogravimetric analysis-mass spectrometry (TG-MS) and quasi- in situ X-ray powder diffraction (XRD) analysis to probe the transformation mechanism from metal oxides (MOs) to MPs during the phosphorization process mediated by hypophosphite. Temperature, time, and the amount of hypophosphite are revealed as the driven forces while oxophilicity and crystallinity as the impeded forces, simultaneously control the component and defect level of a series of MP (M = Ni, Co, W, Mo, and Nb). The as-obtained WO 2.9 /WP is proved to be an efficient Z-scheme photocatalyst for oxidative coupling of methane with the total C 2+ production and C 2 H 4 selectivity in C 2+ products reaching 10.75 µmol·g −1 and 98.25%. Our work provides a fundamental understanding of the phosphorization treatment and thereby guides a viable synthetic route to the controlled synthesis of MO x − δ , MP, MO x − δ /MP, and MP/M heterostructured materials.

Transition metal phosphides (TMPs) are promising candidates for noble metal free electrocatalysts in water splitting applications. In this work, we present the facile synthesis of nickel cobalt phosphide electrocatalyst with three-dimensional nanostructure (3D-NiCoP) on the nickel foam, via hydrothermal reaction and phosphorization. The as-prepared electrocatalyst exhibits an excellent activity for hydrogen evolution reaction (HER) in both acidic and alkaline electrolytes, with small overpotentials to drive 10 mA/cm 2 (80 mV for 0.5 M H 2 SO 4 , 105 mV for 1 M KOH), small Tafel slopes (37 mV/dec for 0.5 M H 2 SO 4 , 79 mV/dec for 1 M KOH), and satisfying durability in long-term electrolysis. 3D-NiCoP also shows a superior HER activity compared to single metal phosphide, such as cobalt phosphide and nickel phosphide. The outstanding performance for HER suggests the great potential of 3D-NiCoP as a highly efficient electrocatalyst for water splitting technology.

The technology of creation the photocathode with quantum efficiency at the level of 5% based on the InP/InGaAs heterostructures is given. The effect of decreasing the quantum efficiency of the photosensitive structure on radiant sensitivity is considered. Several variants of realization of vacuum photoelectronic device with InP/InGaAs photocathode for special purposes are represented.

Electrochemical nitrate reduction to ammonia is a promising alternative strategy to the traditional Haber-Bosch process but suffers from a low Faradaic efficiency and limited ammonia yield due to the sluggish multi-electron/proton-involved steps. Herein, we report a typical hollow cobalt phosphide nanosphere electrocatalyst assembled on a self-supported carbon nanosheet array synthesized with a confinement strategy that exhibits an extremely high ammonia yield rate of 8.47 mmol h −1 cm −2 through nitrate reduction reaction, which is highly superior to previously reported values to our knowledge. In situ experiments and theoretical investigations reveal that the dynamic equilibrium between the generation of active hydrogen on cobalt phosphide and its timely consumption by nitrogen intermediates leads to a superior ammonia yield with a high Faradaic efficiency. This unique insight based on active hydrogen equilibrium provides new opportunities for large-scale ammonia production through electrochemical techniques and can be further used for carbon dioxide capture. While electrochemical conversion of nitrate to ammonia offers a renewable means to remediate waste compounds, it is challenging to achieve selective catalysis. Here, authors demonstrate a strategy to improve electrocatalytic ammonia production using cobalt phosphide on carbon nanosheet arrays.