Tuning the Electrocatalytic Properties of Trimetallic Pentlandites: Stability and Catalytic Activity as a Function of Material Form and Selenium Concentration

Pentlandites are one possible cost-effective alternative to platinum group metals for green hydrogen production. This study delves into the catalytic performance of trimetallic pentlandite systems, exploring the influence of selenium concentration and material form on their efficiency by combining the investigation of materials in various forms (powder catalysts, ingots, and highly densified pellets) with a computational investigation. The experimentally observed solubility limit of selenium was clarified based on the formation energies approach. The best and most stable defect combination, namely, Se:S substitution and S vacancy, was identified and correlated with improved catalytic properties of the systems with small Se addition. Further findings highlight the evolving importance of intrinsic material properties, such as bond properties, intermetallic interactions, or electronic structure, over surface effects, including the activation process, as the material density increases. The research contributes valuable insight into the intricate mechanisms governing pentlandite catalysis. Understanding these dynamics allows for intentional modifications, advancing the application of pentlandites in hydrogen production

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