MoSe is a promising earth-abundant electrocatalyst for the hydrogen-evolution reaction (HER), even though it has received much less attention among the layered dichalcogenide (MX ) materials than MoS so far. Here, a novel hydrothermal-synthesis strategy is presented to achieve simultaneous and synergistic modulation of crystal phase and disorder in partially crystallized 1T-MoSe nanosheets to dramatically enhance their HER catalytic activity. Careful structural characterization and defect characterization using positron annihilation lifetime spectroscopy correlated with electrochemical measurements show that the formation of the 1T phase under a large excess of the NaBH reductant during synthesis can effectively improve the intrinsic activity and conductivity, and the disordered structure from a lower reaction temperature can provide abundant unsaturated defects as active sites. Such synergistic effects lead to superior HER catalytic activity with an overpotential of 152 mV versus reversible hydrogen electrode (RHE) for the electrocatalytic current density of j = -10 mA cm , and a Tafel slope of 52 mV dec . This work paves a new pathway for improving the catalytic activity of MoSe and generally MX -based electrocatalysts via a synergistic modulation strategy.

Hydrogen has been deemed as an ideal substitute fuel to fossil energy because of its renewability and the highest energy density among all chemical fuels. One of the most economical, ecofriendly, and high‐performance ways of hydrogen production is electrochemical water splitting. Recently, 2D transition metal dichalcogenides (also known as 2D TMDs) showed their utilization potentiality as cost‐effective hydrogen evolution reaction (HER) catalysts in water electrolysis. Herein, recent representative research efforts and systematic progress made in 2D TMDs are reviewed, and future opportunities and challenges are discussed. Furthermore, general methods of synthesizing 2D TMDs materials are introduced in detail and the advantages and disadvantages for some specific methods are provided. This explanation includes several important regulation strategies of creating more active sites, heteroatoms doping, phase engineering, construction of heterostructures, and synergistic modulation which are capable of optimizing the electrical conductivity, exposure to the catalytic active sites, and reaction energy barrier of the electrode material to boost the HER kinetics. In the last section, the current obstacles and future chances for the development of 2D TMDs electrocatalysts are proposed to provide insight into and valuable guidelines for fabricating effective HER electrocatalysts.

Highly efficient earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are of great importance for renewable energy conversion systems. Herein, guided by theoretical calculations, we demonstrate highly efficient water splitting in alkaline solution using quarternary mixed nickel iron phosphosulfide (Ni1–x Fe x PS3) nanosheets (NSs), even though neither NiPS3 nor FePS3 is a good HER (or OER) electrocatalyst. With tuned electronic structure and improved electrical conductivity induced by mixing appropriate amount of Fe into NiPS3, Ni0.9Fe0.1PS3 NSs display excellent HER activity (an overpotential of 72 mV vs reversible hydrogen electrode (RHE) at a geometric catalytic current density of −10 mA cm–2 and a Tafel slope of 73 mV dec–1), which is among the best HER catalysts under alkaline conditions. Ni0.9Fe0.1PS3 NSs also show a good apparent OER activity (an overpotential of 329 mV vs RHE at a catalytic current density of 20 mA cm–2 and a Tafel slope of 69 mV dec–1), although structural investigation indicates the formation of Ni­(Fe)­OOH and Ni­(Fe)­(OH)2 layers on the catalyst surface after OER reactions as likely the real active species. These mixed nickel iron phosphosulfide non-precious-metal electrocatalysts with enhanced intrinsic activity and long-term stability and durability should have great potential in overall water-splitting applications.

Developing earth-abundant and highly effective electrocatalysts for hydrogen evolution reaction (HER) is a prerequisite for the upcoming hydrogen energy society. Two-dimensional (2D) high-entropy metal phosphorus trichalcogenides (MPCh3) have the advantages of both near-continuous adsorption energies of high-entropy alloys (HEAs) and large specific surface area of 2D materials, which are excellent catalytic platforms. As a typical 2D high-entropy catalyst, Co0.6(VMnNiZn)0.4PS3 nanosheets with high-concentration active sites are successfully demonstrated to show enhanced HER performance: an overpotential of 65.9 mV at a current density of 10 mA cm–2 and a Tafel slope of 65.5 mV dec–1. Decent spectroscopy characterizations are combined with density function theory analyses to show the scenario for the enhancement mechanism by a high-entropy strategy. The optimized S sites on the edge and P sites on the basal plane provide more active sites for hydrogen adsorption, and the introduced Mn sites boost water dissociation during the Volmer step. Two-dimensional high-entropy MPCh3 provides an avenue for the combination of HEAs and 2D materials to enhance the HER performance, which also provides an alternative materials platform to explore and design superior catalysts for various electrochemical systems.

Developing earth-abundant and low-cost electrocatalysts for water splitting is important for the conversion systems of renewable and clean energy. Herein, under the guidance of theoretical calculations, a new type of skutterudite-type ternary cobalt nickel phosphide (Co1–x Ni x P3) nanoneedle arrays (NAs) is fabricated on carbon cloth for the splitting of water. The electronic structure was tuned by doping an appropriate amount of Ni, and the resultant Co0.93Ni0.07P3 displayed good catalytic activity toward hydrogen evolution reaction (HER) with an overpotential (η10) of 87 mV versus reversible hydrogen electrode (RHE) when the current density reaches −10 mA cm–2 and the Tafel slope of the catalyst is 60.7 mV dec–1 in alkaline electrolyte. In addition, the Co0.93Ni0.07P3 also exhibited an OER activity (η20 of 221 mV vs RHE and the Tafel slope of 83.7 mV dec–1). These skutterudite-based Co1–x Ni x P3 electrocatalysts show promising potential in the applications of overall water splitting in an alkaline environment.