Electrocatalytic trends of different Cantor entropy alloys for alkaline and acidic hydrogen-evolution reactions

Medium- and high-entropy alloys (MEAs and HEAs) are the basis of unique electrocatalysts for hydrogen-evolution reactions (HERs) due to their tunable chemical compositions and microstructures. Here, various Cantor MEAs (CoFeNi, CoFeNiMn, CoFeNiCr) and a HEA (CoFeNiMnCr) made up of affordable non-noble transitional metals with different structures (primary matrix and secondary phases, grain sizes, lattice parameters) were successfully synthesized with an inert-gas melting process. A close correlation was established between their physicochemical properties (elemental composition, microstructure, crystal structure) and the hydrogen-binding ability of the elements in the alloy on the electrocatalytic HER activity and stability in alkaline and acidic media. Advanced performances of electrocatalysts toward HERs were revealed in a specially designed electrochemical cell. Effectively identifying these electrocatalytic trends lays the groundwork for the strategic design of multi-component alloy electrocatalysts for practical HERs. • MEAs and HEA composed of non-noble transition metals were successfully synthesized by an inert melting process. • Prepared electrocatalysts exhibited very promising electrocatalytic activity and stability for alkaline and acidic HER. • A close correlation between the physicochemical and electrochemical properties of MEAs and HEA for HER has been established.