Template-assisted Fabrication of O-doped CoP Microflowers with Optimal Electronic Modulation for Electrochemical Hydrogen Evolution

Exploring efficient, affordable and stable electrocatalyst toward hydrogen evolution reaction (HER) is of great scientific significance for the practical implementation of the water splitting. The heteroatom doping represents a serviceable strategy to further elevate the catalytic performance for a transition metal-based electrocatalyst because of the electronic regulation effect. Herein, a reliable self-sacrificial template-engaged approach is proposed to synthesize O-doped CoP (denoted as O-CoP) microflowers, which simultaneously considers the regualtion of electronic configuration via anion doping and sufficient exposure of active sites via nanostructure engineering. The suitable O incorporation content in CoP matrix could tremendously modify the electronic configuration, accelerate the charge transfer, promote the exposure of active sites, strengthen the electrical conductivity, and adjust the adsorption state of H*. Consequently, the optimized O-CoP microflowers with optimal O concentration display a remarkable HER property with a small overpotential of 125 mV to afford a current density of 10 mA cm-2 , a low Tafel slope of 68 mV dec-1 and long-term durability for 32 h under alkaline electrolyte, manifesting a considerable potential application for hydrogen production at large scale. The integration of anion incorporation and architecture engineering in this work will bring in a depth insight for the design of low-cost and effective electrocatalysts in energy conversion and storage systems.

V-doped Ni2P nanoparticle grafted g-C3N4 nanosheets for enhanced photocatalytic hydrogen evolution performance under visible light

Exploring low-cost and highly active photocatalysts with noble metal-free cocatalysts is of great significance for photocatalytic hydrogen evolution under simulated sunlight irradiation. In this work, a novel V-doped Ni₂P nanoparticle loaded g-C₃N₄ nanosheet is reported as a highly efficient photocatalyst for H₂ evolution under visible light irradiation. The results demonstrate that the optimized 7.8 wt% V-Ni₂P/g-C₃N₄ photocatalyst exhibits a high hydrogen evolution rate of 271.5 μmol g^-1 h^-1, which is comparable to that of the 1 wt% Pt/g-C₃N₄ photocatalyst (279 μmol g^-1 h^-1), and shows favorable hydrogen evolution stability for five successive runs within 20 h. The remarkable photocatalytic hydrogen evolution performance of V-Ni₂P/g-C₃N₄ is mainly due to the enhanced visible light absorption ability, the facilitated separation of photo-generated electron-hole pairs, the prolonged lifetime of photo-generated carriers and the fast transmission ability of electrons.

Nitrogen Disturbance Awakening the Intrinsic Activity of Nickel Phosphide for Boosted Hydrogen Evolution Reaction

Nickel phosphide (Ni₂ P) has emerged as a promising candidate to substitute Pt-based catalysts for hydrogen evolution reaction (HER) due to the hydrogenase-like catalytic mechanism and concomitantly low cost. However, its catalytic activity is still not comparable to that of noble-metal-based catalysts, and innovative strategies are still urgently needed to further improve its performance. Herein, a self-supported N-doped Ni₂ P on Ni foam (N-Ni₂ P/NF) was rationally designed and fabricated through a facile NH₄ H₂ PO₂ -assisted gas-solid reaction process. As an HER catalyst in alkaline medium, the obtained N-Ni₂ P/NF revealed excellent electrocatalytic performance with a distinctly low overpotential of 50 mV at 10 mA cm^-2 , a small Tafel slope of 45 mV dec^-1 , and long-term stability for 25 h. In addition, the spectroscopic characterizations and density functional theory calculations confirmed that the incorporation of N regulated the original electronic structure of Ni₂ P, enhanced its intrinsic catalytic property, optimized the Gibbs free energy of reaction intermediates, and ultimately promoted the HER process. This work provides an atomic-level insight into the electronic structure modulation of metal phosphides and opens an avenue for developing advanced transition metal phosphides-based catalysts.

Transition Metal Non-Oxides as Electrocatalysts: Advantages and Challenges

The identification of hydrogen as green fuel in the near future has stirred global realization toward a sustainable outlook and thus boosted extensive research in the field of water electrolysis focusing on the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). A huge class of compounds consisting of transition metal-based nitrides, carbides, chalcogenides, phosphides, and borides, which can be collectively termed transition metal non-oxides (TMNOs), has emerged recently as an efficient class of electrocatalysts in terms of performance and longevity when compared to transition metal oxides (TMOs). Moreover, the superiority of TMNOs over TMOs to effectively catalyze not only OERs but also HERs and ORRs renders bifunctionality and even trifunctionality in some cases and therefore can replace conventional noble metal electrocatalysts. In this review, the crystal structure and phases of different classes of nanostructured TMNOs are extensively discussed, focusing on recent advances in design strategies by various regulatory synthetic routes, and hence diversified properties of TMNOs are identified to serve as next-generation bi/trifunctional electrocatalysts. The challenges and future perspectives of materials in the field of energy conversion and storage aiding toward a better hydrogen economy are also discussed in this review.

Nanostructured Metal Phosphide Based Catalysts for Electrochemical Water Splitting: A Review

Amongst various futuristic renewable energy sources, hydrogen fuel is deemed to be clean and sustainable. Electrochemical water splitting (EWS) is an advanced technology to produce pure hydrogen in a cost-efficient manner. The electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are the vital steps of EWS and have been at the forefront of research over the past decades. The low-cost nanostructured metal phosphide (MP)-based electrocatalysts exhibit unconventional physicochemical properties and offer very high turnover frequency (TOF), low over potential, high mass activity with improved efficiency, and long-term stability. Therefore, they are deemed to be potential electrocatalysts to meet practical challenges for supporting the future hydrogen economy. This review discusses the recent research progress in nanostructured MP-based catalysts with an emphasis given on in-depth understanding of catalytic activity and innovative synthetic strategies for MP-based catalysts through combined experimental (in situ/operando techniques) and theoretical investigations. Finally, the challenges, critical issues, and future outlook in the field of MP-based catalysts for water electrolysis are addressed.

Regulation of morphology and electronic configuration of NiCo2O4 by aluminum doping for high performance supercapacitors

Morphology engineering and element doping are two effective strategies to boost the capacitive performance of electroactive materials. The morphology control through doping process is conducive to simplifying the preparation process. Herein, an aluminum-doped (Al-doped) strategy was used to prepare Al-doped NiCo₂O₄ nanosheet-wire structure (Al-NiCo₂O₄ NSW) by hydrothermal method and subsequent calcination. The nanosheet-wire structure was composed of one-dimensional (1D) nanowires and two-dimensional (2D) ultrathin nanosheets. 1D nanowires can provide efficient pathways for the electrons/ions transport. 2D nanosheets can enlarge the specific surface area and expose more active sites. The Al doping can change the electronic structure of NiCo₂O₄ with enhanced electrical conductivity as revealed by density functional theory (DFT) calculations. Meanwhile, a strong adsorption capacity of OH^- was obtained on Al-NiCo₂O₄ NSW for redox reactions. The Al-NiCo₂O₄ NSW electrode demonstrated a high specific capacity of 1441C g^-1 (2446F g^-1) at 1 A g^-1 and excellent cycling stability (87.6% capacity retention at 10 A g^-1 for 5000 charge-discharge cycles). The assembled asymmetric supercapacitor manifested a superior energy density of 46.2 Wh Kg^-1 at a power density of 800 W kg^-1.

Progress in the development of heteroatom-doped nickel phosphates for electrocatalytic water splitting

Hydrogen energy is expected to replace fossil fuels as a mainstream energy source in the future. Currently, hydrogen production via water electrolysis yields high hydrogen purity with easy operation and without producing polluting side products. Presently, platinum group metals and their oxides are the most effective catalysts for water splitting; however, their low abundance and high cost hinder large-scale hydrogen production, especially in alkaline and neutral media. Therefore, the development of high-efficiency, durable, and low-cost electrocatalysts is crucial to improving the overpotential and lowering the electrical energy consumption. As a solution, Ni₂P has attracted particular attention, owing to its desirable electrical conductivity, high corrosion resistance, and remarkable catalytic activity for overall water splitting, and thus, is a promising substitute for platinum-group catalysts. However, the catalytic performance and durability of raw Ni₂P are still inferior to those of noble metal-based catalysts. Heteroatom doping is a universal strategy for enhancing the performance of Ni₂P for water electrolysis over a wide pH range, because the electronic structure and crystal structure of the catalyst can be modulated, and the adsorption energy of the reaction intermediates can be adjusted via doping, thus optimizing the reaction performance. In this review, first, the reaction mechanisms of water electrolysis, including the cathodic hydrogen evolution reaction and anodic oxygen evolution reaction, are briefly introduced. Then, progress into heteroatom-doped nickel phosphide research in recent years is assessed, and a discussion of each representative work is given. Finally, the opportunities and challenges for developing advanced Ni₂P based electrocatalysts are proposed and discussed.

Recent Advances in Multimetal and Doped Transition-Metal Phosphides for the Hydrogen Evolution Reaction at Different pH values

Hydrogen is a fuel with a potentially zero-carbon footprint viewed as a viable alternative to fossil fuels. It can be produced in a large scale via electrochemical water splitting using electricity derived from renewable sources, but this would require highly active, inexpensive, and stable hydrogen evolution reaction (HER) catalysts to replace the Pt benchmark. Transition-metal phosphides (TMPs) are potential Pt replacements owing to their generally high activity as well as versatility as HER catalysts for different pH media. This review summarizes the recent progress in the development of TMP HER electrocatalysts, focusing on the strategies that have been recently explored to tune the activity in acidic, neutral, and basic media. These strategies are the doping of TMPs with metal and nonmetal elements, fabrication of multimetallic phosphide phases, and construction of multicomponent heterostructures comprising TMPs and another component such as a different TMP or a metal oxide/hydroxide. The synthetic methods utilized to design the catalysts are also presented. Finally, the challenges still remaining and future research directions are discussed.

Ni(OH)2 derived Ni-MOF supported on carbon nanowalls for supercapacitors

Metal organic frameworks (MOFs) are expected to be promising pseudocapacitve materials because of their potential redox sites and porous structures. Nevertheless, the conductivity inferiority of MOF strongly decreases their structural advantages, therefore resulting in unsatisfying electrochemical performance. Herein, we propose an efficient strategy to enhance conductivity and thus electrochemical properties, in Ni(OH)₂ is electrochemically deposited on carbon nanowalls as the precursor for oriented MOF. The synthesized vertically oriented MOF sheets show an almost triple high capacitance of 677 F g^-1 than MOF powder of 239 F g^-1 at the current density of 2 A g^-1. Correspondingly, an asymmetric supercapacitor is fabricated, which can deliver a maximum energy density of 20.7 Wh kg^-1 and a maximum power density of 23 200 W kg^-1. These promising results indicate that modulating the conductivity of MOF is the key step to pursuit upgrading electrochemical performance.

Synergistic effect of S-bridged Fe-Ni group on hydrogen evolution for pentlandite

Pentlandite is reported to exhibit good catalytic activity in hydrogen evolution reaction (HER). Many studies have paid attention to metal catalysis of pentlandite. However, the nonmetal catalysis is not considered for HER. Here, we unravel one probable catalytic mechanism of pentlandite toward HER using density functional theory. In our study models, (001) and (100) surfaces are created because there are three types of S-bridged M-M groups on them. Our study reveals that (Fe-Ni)-S center has a moderate value of Gibbs free energy while the corresponding value for (Fe-Fe)-S or (Ni-Ni)-S center is largely positive or negative. In (Fe-Ni)-S group, Fe and Ni can regulate the antibonding state of S, and then balance adsorption and desorption of proton. In addition, an intrinsic electronic potential difference exists between Fe and Ni in (Fe-Ni)-S group, which may boost the charge transfer. Particularly, (Fe-Ni)-S groups are perpendicular to the surface, and four of them make up one closed loop in the surface. It is suggested that the behaviors of such configuration composed of reaction centers resemble edge sites along the layers of MoS₂ toward HER. This study provides a deep insight into the synergistic effect of S-bridged Fe-Ni groups and enables the modulation of electrocatalytic reaction of pentlandite toward HER.

Controllable design of 3D hierarchical Co/Ni-POM nanoflower compounds supported on Ni foam for the hydrogen evolution reaction

The outstanding HER activity of Co/Ni-POM/NF stems from the synergistic effect between the metallic elements of the Co/Ni-POM and its large specific surface area.

Nanostructured metal phosphides: from controllable synthesis to sustainable catalysis

Metal phosphides (MPs) with unique and desirable physicochemical properties provide promising potential in practical applications, such as the catalysis, gas/humidity sensor, environmental remediation, and energy storage fields, especially for transition metal phosphides (TMPs) and MPs consisting of group IIIA and IVA metal elements. Most studies, however, on the synthesis of MP nanomaterials still face intractable challenges, encompassing the need for a more thorough understanding of the growth mechanism, strategies for large-scale synthesis of targeted high-quality MPs, and practical achievement of functional applications. This review aims at providing a comprehensive update on the controllable synthetic strategies for MPs from various metal sources. Additionally, different passivation strategies for engineering the structural and electronic properties of MP nanostructures are scrutinized. Then, we showcase the implementable applications of MP-based materials in emerging sustainable catalytic fields including electrocatalysis, photocatalysis, mild thermocatalysis, and related hybrid systems. Finally, we offer a rational perspective on future opportunities and remaining challenges for the development of MPs in the materials science and sustainable catalysis fields.

V-Doped CoP Nanosheet Arrays as Highly Efficient Electrocatalysts for Hydrogen Evolution Reaction in Both Acidic and Alkaline Solutions

It is of significant necessity to explore inexpensive and high-active electrocatalysts toward hydrogen evolution reaction (HER) in both acidic and basic media. In this work, V-doped CoP nanosheet arrays supported on the carbon cloth (V-CoP/CC) are fabricated though a facile water-bath/phosphorization method. The nanoarray structure on the three-dimensional self-supporting electrode can provide a large electrochemical active surface area with more exposed active sites to accelerate the reaction kinetics. Furthermore, V doping is able to tune the electronic properties and thus enhance the intrinsic catalytic activity of CoP. Consequently, the V-CoP/CC electrode exhibits excellent electrocatalytic activities toward HER in both 0.5 M H₂SO₄ and 1 M KOH solutions with small overpotentials of 88 and 98 mV at a current density of 10 mA cm⁻², respectively. The present work will offer a feasible way to tailor the catalytic activity by hetero-atoms doping toward HER.

Fe-Doped Co-Mo-S microtube: a highly efficient bifunctional electrocatalyst for overall water splitting in alkaline solution

Fe-Doped Co-Mo-S microtubes were successfully synthesized through a multistep synthetic route, employing MoO3 microrods as the sacrificial template, Co(NO3)2·6H2O and Fe(SO4)2·7H2O as the metal sources, 2-methylimidazole (2-MI) as the ligand and thioacetamide (TAA) as the S2- ion source. The as-prepared products were characterized by X-ray powder diffraction (XRD), energy dispersive spectrometry (EDS), inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), (high-resolution) transmission electron microscopy (TEM/HRTEM) and HAADF-STEM-EDS elemental mapping. Experiments showed that the as-obtained Fe-doped Co-Mo-S microtube catalyst demanded overpotentials of ∼105 and 268 mV to afford the current density of -10 mA cm-2 for hydrogen evolution reaction (HER) and 10 mA cm-2 for oxygen evolution reaction (OER) with a durability of 60 h in 1.0 M KOH solution, respectively. In a two-electrode water-splitting device, the as-prepared Fe-doped Co-Mo-S microtubes acted as both anode and cathode simultaneously. To deliver a current density of 10 mA cm-2, a cell voltage of 1.605 V was required in 1.0 M KOH solution. After continuously catalyzing the overall water splitting for 60 h, the overpotential hardly changed, implying remarkable long-term stability. Obviously, the present Fe-doped Co-Mo-S microtubes have potential applications as bifunctional catalysts for electrochemical water splitting.

Transition Metal Phosphide-Based Materials for Efficient Electrochemical Hydrogen Evolution: A Critical Review

As hydrogen has been increasingly considered as promising sustainable energy supply, electrochemical overall water splitting driven by highly efficient non-noble metal electrocatalysts has aroused extensive attention. Transition metal phosphides (TMPs) have demonstrated remarkable electrocatalytic performance, including high activity and robust durability towards hydrogen evolution reaction (HER) in acidic and alkaline as well as neutral electrolytes. In this Review, up-to-date progress of TMP-based HER electrocatalysts is summarized. Various synthesis strategies of TMPs based on selected phosphorus sources are presented, and the reaction mechanisms of HER as well as the contribution of phosphorus in the TMPs to HER activity are briefly discussed. The multiscale approaches for promoting the activity and stability of TMP-based catalysts are discussed with respect to intrinsic electronic structure, hybrids, microstructure, and working electrode interface. Some crucial issues and future perspectives of TMPs are pointed out. These modulated approaches and challenges are also instructive for constructing other high-activity energy-related electrocatalysts.

Ultrafine Co3O4 nanolayer-shelled CoWP nanowire array: a bifunctional electrocatalyst for overall water splitting

The development of bifunctional electrocatalysts based on highly efficient non-noble metals is pivotal for overall water splitting. Here, a composite electrode of Co₃O₄@CoWP is synthesized, where an ultrathin layer composed of Co₃O₄ nanoparticles is grown on CoWP nanowires supported on a carbon cloth (CC). The Co₃O₄@CoWP/CC electrode exhibits excellent electrocatalytic activity and improved kinetics towards both the oxygen and hydrogen evolution reactions (OER and HER). The Co₃O₄@CoWP/CC electrode achieves a current density of 10 mA cm⁻² at a low overpotential of 269 mV for the OER and −10 mA cm⁻² at 118 mV for the HER in 1.0 M KOH solution. The voltage applied to a two-electrode water electrolyzer for overall water splitting, while employing the Co₃O₄@CoWP/CC electrode as both an anode and a cathode, in order to reach a current density of 10 mA cm⁻², is 1.61 V, which is better than that for the majority of reported non-noble electrocatalysts. Moreover, the Co₃O₄@CoWP/CC electrode exhibits good stability over 24 h with slight attenuation. The electrode benefits from the enhanced adsorption of oxygen intermediates on Co₃O₄ during the OER, the increased ability for water dissociation and the optimized H adsorption/desorption ability of CoWP nanowires during the HER. This study provides a feasible approach for cost-effective and high-performance non-noble metal bifunctional catalysts for overall water electrolysis.

A hierarchical 3D self-supporting CoWP nanowire array shelled with an ultrathin Co₃O₄ nanolayer on carbon cloth (Co₃O₄@CoWP/CC) exhibits superior overall water electrolysis capability.

In situ conversion of layered double hydroxide arrays into nanoflowers of NixV1−x-MOF as a highly efficient and stable electrocatalyst for the oxygen evolution reaction

The Ni_0.9V_0.1-MOF exhibits superior catalytic OER performance, needing an overpotential of 290 mV at 150 mA cm⁻² in alkaline media.

New Insights into Layered Graphene Materials as Substrates to Regulate Synthesis of Ni-P Nanomaterials for Electrocatalytic Oxidation of Methanol and Water

The doping ring-core nickel phosphide/graphene nanomaterial is obtained by H₂ reduction of the flower-like nickel phosphates/graphene oxide (NiPOGO) and sea urchin-like nickel phosphates/chemically converted graphene (NiPOG) substrates. The obtained structure of nickel phosphates depends on the influence of different kinds of oxygen-containing groups on the graphene substrate. The substrate can also affect the particle size and distribution of nickel phosphate nanoparticles. The substrate can adjust the particle size, distribution, and exposed growth direction of nickel phosphide. These materials with high activity are employed as electrochemical catalysts for methanol oxidation reactions, which is ∼7 times that of pure nickel phosphide, and there is a very small Tafel slope of 47 mV decade^-1 in the water oxidation reaction. Our results highlight that the substrate structure is essential to catalytic materials for electrochemical oxidation of methanol and water.

NiFeP nanoflakes composite with CoP on carbon cloth as flexible and durable electrocatalyst for efficient overall water splitting

High-performance and earth-abundant NiFeP is an excellent bifunctional catalyst for water splitting in acidic and alkaline environments, and NiFeP nanoflakes on CoP layer composite with a conductive carbon cloth (CC) substrate as the trunk-leaf flexible structure (NiFeP/CoP/CC) is prepared by direct high-temperature phosphorization. Overpotentials of only 96.38 and 78.80 mV are required in hydrogen evolution reaction in 1 M KOH and 0.5 M H₂SO₄, respectively, to generate an electrocatalytic current density of 10 mA cm^-2. A small Tafel slope of 70.67 and 63.21 mV per decade are also observed from NiFeP/CoP/CC revealing a Volmer-Heyrovsky mechanism in both media. The electrocatalyst also delivers excellent oxygen evolution reaction performance in the alkaline environment and long-term electrochemical durability for at least 24 h in electrolytes over a wide pH range. A device is assembled with two identical flexible ultrathin NiFeP/CoP/CC as both the anode and cathode in 1 M KOH driven by a set of 1.6 V solar cells. During 32 h of electrolysis, the results show that the current of our electrodes maintains 80% performance at a constant voltage of 1.7 V for 32 h, and the NiFeP/CoP/CC anodes and cathodes have large potential in industrial alkaline water splitting.

Hollow Nanotube Ru/Cu2+1 O Supported on Copper Foam as a Bifunctional Catalyst for Overall Water Splitting

Hydrogen energy is considered as one of the ideal clean energies for solving the energy shortage and environmental issues, and developing highly efficient electrocatalysts for overall water splitting to produce hydrogen is still a huge challenge. Herein, for the first time, Ru-doped Cu₂₊₁ O vertically arranged nanotube arrays in situ grown on Cu foam (Ru/Cu₂₊₁ O NT/CuF) are reported and further investigated for their catalytic properties for overall water splitting. The Ru/Cu₂₊₁ O NT/CuF presents ultrahigh catalytic activities for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline conditions, and it exhibits a small overpotential of 32 mV at 10 mA cm^-2 in the HER, and only needs 210 mV overpotential to achieve a current density of 10 mA cm^-2 in the OER. Importantly, the alkaline electrolyzer using Ru/Cu₂₊₁ O NT/CuF as a bifunctional electrocatalyst only needs 1.53 V voltage to deliver a current density of 10 mA cm^-2 , which is much lower than the benchmark of IrO₂ (+)/Pt(-) counterpart (1.64 V at 10 mA cm^-2 ). The excellent performance of the Ru/Cu₂₊₁ O NT/CuF catalyst is attributed to its high conductive substrate and special Ru-doped nanotube structure, which provides a high electrochemical active surface area and 3D gas diffusion channel.

Ni3N/NF as Bifunctional Catalysts for Both Hydrogen Generation and Urea Decomposition

Oxygen evolution reaction (OER) has a high overpotential, which can significantly reduce the energy efficiency in water decomposition. Using urea oxidation reaction (UOR) to replace OER has been a feasible and energy-saving approach because of its lower electrode potential. Furthermore, UOR is also an important process in wastewater treatment. This paper successfully synthesizes a high-performance bifunctional catalyst for urea electrolysis. The catalyst is nickel nitride bead-like nanospheres array supported on Ni foam (Ni₃N/NF). Several characterization methods are used to analyze the catalyst's morphology, structure, and composition as well as catalytic activity/stability, including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical methods (cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy, and CAM). A concurrent two-electrode electrolyzer (Ni₃N/NF∥Ni₃N/NF) is constructed and used to validate the catalyst performance, and the results show that the cell achieves 100 mA·cm^-2 at 1.42 V, while the cell voltage of Pt/C∥IrO₂ is 1.60 V, indicating that the Ni₃N/NF catalyst is superior to precious metals.

Flexible vanadium-doped Ni2P nanosheet arrays grown on carbon cloth for an efficient hydrogen evolution reaction

Tuning the electronic structure, morphology, and structure of electrocatalysts is of great significance to achieve a highly active and stable hydrogen evolution reaction (HER). Herein, combining hydrothermal and low temperature phosphidation methods, V-doped Ni2P nanosheet arrays grown on carbon cloth (V-Ni2P NSAs/CC) were successfully prepared for the HER. It is found that the prepared V-Ni2P NSAs/CC exhibits preeminent performance for the HER. Specifically, it only requires an overpotential of 85 mV to achieve a current density of 10 mA cm-2 in 1.0 M KOH solution. Moreover, the V-Ni2P NSAs/CC shows superior electrochemical stability, maintaining its HER performance up to 3000 cyclic voltammetry cycles. This work affords a guiding strategy for the synthesis of a high-performance and stable electrocatalyst for the HER.

Self-supported Al-doped cobalt phosphide nanosheets grown on three-dimensional Ni foam for highly efficient water reduction and oxidation

Al-doped CoP nanosheets self-supported on Ni foam are shown to be an efficient bifunctional electrocatalyst for long-time overall water splitting.

Enhanced electrocatalytic activity of water oxidation in an alkaline medium via Fe doping in CoS2 nanosheets

Fe–CoS₂/CC exhibits enhanced catalytic OER performance, needing an overpotential of 302 mV at 10 mA cm⁻² in 1.0 M KOH.

Nitrogen and phosphorous co-doped graphitic carbon encapsulated ultrafine OsP2 nanoparticles: a pH universal highly durable catalyst for hydrogen evolution reaction

Synthesis of a high performance pH universal electrochemical hydrogen evolution catalyst based on OsP₂.

A novel FeS–NiS hybrid nanoarray: an efficient and durable electrocatalyst for alkaline water oxidation

A novel FeS–NiS/TM nanosheet array was developed for alkaline OER; this catalyst only requires an overpotential of 260 mV to afford a current density of 10 mA cm⁻² in 1.0 M KOH.

Recent progress in transition metal phosphides with enhanced electrocatalysis for hydrogen evolution

Increasing demand for hydrogen energy has boosted the exploration of inexpensive and effective catalysts. Transition metal phosphides (TMPs) have been proven as excellent catalysts for the hydrogen evolution reaction (HER). Very recently, the search for TMP-based catalysts has being mainly directed at enhanced electrocatalytic performance. Hence, a concluded guideline for enhancing HER activity is highly desired. In this mini review, we briefly summarize the most recent and instructive developments in the design of TMP-based catalysts with enhanced electrocatalysis for hydrogen evolution from composition and structure engineering strategies. These strategies and perspectives are also meaningful for designing other inexpensive and high-performance catalysts.

Ni(OH)2 -WP Hybrid Nanorod Arrays for Highly Efficient and Durable Hydrogen Evolution Reactions in Alkaline Media

The development of efficient non-noble-metal hydrogen evolution electrocatalysts in alkaline media is crucial for sustainable, ecofriendly production of H₂ through water electrolysis. An alkaline hydrogen evolution reaction (HER) catalyst composed of Ni(OH)₂ -decorated thungsten phosphide (WP) nanorod arrays on carbon paper was synthesized by thermal evaporation and electrodeposition. This hybrid catalyst displayed outstanding HER activity and required a low overpotential of only 77 mV to obtain a current density of 10 mA cm^-2 and a Tafel slope of 71 mV dec^-1 . The hybrid catalyst also showed long-term electrochemical stability, maintaining its activity for 18 h. This improved HER efficiency was attributed to the synergetic effect of WP and Ni(OH)₂ : Ni(OH)₂ effectively lowers the energy barrier during water dissociation and also provides active sites for hydroxyl adsorption, whereas WP adsorbs hydrogen intermediates and efficiently produces H₂ gas. This interfacial cooperation offers not only excellent HER catalytic activity but also new strategies for the fabrication of effective non-noble-metal-based electrocatalysts in alkaline media.