HERFD XAS operando study of Re and Mo ultradispersed sulfide electrocatalysts of hydrogen production

Hydrogen production is a major axis for the future energy transition. Sulfide catalysts and in particular MoS2 are widely studied for electrochemical hydrogen evolution (HER). Our preliminary data show that atomically dispersed Mo, Re and Mo-Re sulfide clusters are highly active in the HER. However their catalytic action is far from being understood. For example, since ultradispersed sulfide clusters are very prone to oxidation, it is unclear whether the active species are sulfide or oxysulfide ones. In this proposal by combining high resolution XANES with catalysts ultradispersion we strive to unravel the catalytic mechanisms in the ultradispersed sulfides: to study the structure of ultradispersed Mo, Re and Mo-Re sulfide species and to compare them with the nanoparticle references; to clarify the electronic effects in the mixed Mo-Re sulfide species and to follow redox transformations of ultradispersed sulfide clusters in a wide range of electrochemical potentials.