The growing global energy demand and environmental concerns highlight the need for efficient and sustainable clean energy technologies. (1−4) Among various clean energy carriers, hydrogen has emerged as a promising alternative to fossil fuels owing to its high gravimetric energy density and zero carbon emissions. (5−7) Water electrolysis is a key method for producing “green” hydrogen using renewable electricity, but its efficiency is significantly constrained by the intrinsically sluggish kinetics of the hydrogen evolution reaction (HER) at the cathode. Efficient electrocatalysts are essential to lower the energy barrier (overpotential) of this reaction. (8−11) Although noble metal-based catalysts, particularly Pt, remain the benchmark for HER performance, their high cost and limited natural abundance severely restrict large-scale industrial applications. (12−18) This has spurred intensive research into earth-abundant alternatives. (19) In this context, 3d transition metal-based materials represented by iron (Fe), cobalt (Co), and nickel (Ni) have attracted extensive attention as promising alternatives to noble metal catalysts due to their natural abundance, low cost, and considerable catalytic potential. Accordingly, a variety of catalytic systems have been developed, including transition metal oxides, hydroxides, sulfides, phosphides, nitrides, and alloys, achieving substantial progress in water electrolysis. (20−22) Among them, transition metal selenides (TMSes) have gained considerable attention due to their tunable electronic structures, favorable hydrogen adsorption free energy, and good electrical conductivity, rendering them promising candidates for HER in alkaline media. (23−25)

Nevertheless, traditional TMSes often suffer from limitations such as insufficient density of catalytically active sites and poor long-term stability under high current densities, which restrict their practical applications. (26,27) The synergistic interactions arising from multimetal compositions can optimize the hydrogen adsorption free energy and accelerate the reaction kinetics. (28) High-entropy materials (HEMs), composed of five or more principal elements in near-equimolar ratios, exhibit unique properties such as high-entropy effects, severe lattice distortion, sluggish diffusion kinetics, and cocktail effects. These characteristics contribute to superior electrocatalytic performance compared to lower-entropy counterparts. (29,30) The compositional tunability of HEMs allows for the design of catalysts with optimized electronic structures, leading to enhanced intrinsic activity and improved stability. (31) For instance, Jiang et al. (32) demonstrated the superior performance of a flower-like high-entropy selenide (CoNiFeCuCr)Se synthesized via a two-step solvothermal method, outperforming its quaternary, ternary, binary, and unary analogues. Furthermore, in situ growth of catalytic materials on conductive substrates like metallic foams presents significant advantages: it circumvents the need for polymeric binders, which can impede conductivity and block active sites, provides excellent electrical contact, facilitates mass transport through inherent porosity, and ensures robust mechanical adhesion. (33,34) Crucially, the physicochemical properties and electrocatalytic performance of selenide catalysts are strongly dependent on selenization parameters, particularly the temperature and duration. These factors govern the kinetics of metal–selenium bond formation, thus affecting the crystallinity, phase composition, and nature of the active phases. Therefore, controlling selenization conditions is vital for tailoring the electrocatalytic properties of high-entropy selenides...

Ziwu Liu - Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization, School of Chemical Engineering and Jiangsu Province Engineering Laboratory of High Efficient Energy Storage Technology and Equipment, China University of Mining & Technology, Xuzhou ,221008Jiangsu, China;