Cobalt-Rich Multimetallic Selenides-Exploring Relationships between Chemical Composition, Temperature Treatment, and Electrocatalytic Performance of Solid Electrodes

Multicomponent, transition-metal selenides characterized by TM3Se4 stoichiometry, and monoclinic pseudospinel structure were recently reported as promising catalysts for water-splitting processes. However, the initial data indicate that the simple increase in the number of composing elements might not be sufficient to maximize their performance, with the systematic screening of the different regions of multicomponent phase diagrams proving to be the most effective approach. Thus, in this work, a series of highly conductive bimetallic and trimetallic selenides were synthesized using a high-temperature synthesis and inductive hot-pressing method. Their electrocatalytic activity toward hydrogen evolution reaction was studied and correlated with the chemical composition and corresponding electronic structure, as well as temperature treatment and related microstructure, on both theoretical and experimental grounds. A clear dependence between the composition of the material, its processing, and catalytic activity was established, allowing for a better understanding and more efficient design of catalysts belonging to this material group.