Novel electrocatalysts via mechanochemistry: Binary & ternary mixed transition metal dichalcogenides

This study investigated the preparation of 2D transition metal dichalcogenide (TMD) hybrids via mechanochemical activation and examined their catalytic activity towards the hydrogen evolution reaction (HER). Binary and ternary mixtures of TMD materials were prepared and characterized, focusing on their electrochemical performance. The ternary hybrids exhibited superior HER activity compared to binary hybrids, with MoS₂+MoSe₂+WS₂ demonstrating the lowest onset potential (-0.47 V vs Ag/AgCl). Tafel slope calculations indicated that ternary hybrids generally exhibited lower Tafel values, suggesting enhanced reaction kinetics. Both binary and ternary hybrids followed a Volmer-Heyrovsky mechanism, where the Volmer discharge step was rate-determining for HER. Electrochemical rate constant determination revealed varying values (ranging from 0.52 × 10^–3 cm s^-1 to 8.2 × 10^–3 cm s^-1) among the TMD hybrids, with mixtures containing selenium components generally exhibiting higher rate constants than those without. This improvement in catalytic activity was attributed to increased surface area, combined effect of two or more TMDs and potential exfoliation of TMDs during mechanochemical processing, exposing more active sites for HER. These findings underscore the potential of mechanochemically prepared TMD hybrids as efficient HER electrocatalysts.