Electrochemical Hydrogen Evolution Reaction of Supported Pt Nanoclusters on MoS₂: Cluster Expansion Investigation

Supported metal nanoclusters on MoS₂ have shown catalytic activity towards hydrogen evolution reaction (HER) that is comparable or better than bulk Pt. We use density functional theory calculations in conjunction with cluster expansion and ab initio thermodynamics to investigate the activity of supported Ptnanoclusters on MoS₂. We determine the hydrogen adsorption configurations under HER conditions by including multiple adsorption sites. Our results show that both Volmer-Heyrovsky and Volmer-Tafel reactions are facile on the cluster while as only the Volmer-Tafel reaction is observed for Pt (111) surfaces. This results in enhanced catalytic activity of the nano cluster. The underpinning of this behavior is discussed.