Atomic‐Scale Robust Modulation of Pt on Monolayer MoS₂ for Enhanced on‐Chip Hydrogen Evolution Reaction

Abstract Maintaining high catalytic performance while maximizing metal atom utilization requires atomic‐level modulation of catalyst microstructure in noble‐metal catalyst design. On‐chip microreactors enable precise measurements of catalytic activity in specific regions, advancing the understanding of structure‐property relationships. Here, Pt single atoms (SAs), clusters, and sub‐2.5 nm nanoparticles (NPs) are synthesized on monolayer MoS₂ via defect‐anchoring. On‐chip electrochemical measurements during hydrogen evolution reaction (HER) demonstrated that Pt clusters‐MoS₂ exhibited superior activity, achieving a 94 mV overpotential at 10 mA cm⁻², much lower than that of Pt SAs‐MoS₂ (202 mV) and Pt NPs‐MoS₂ (259 mV). Density functional theory calculations revealed that the electron transfer from MoS₂ to Pt clusters altered H* adsorption site, yielding a near‐zero Gibbs free energy for enhanced HER activity. The work reveals the structure‐property relationships in Pt‐modified MoS₂ catalysts, guiding atom‐efficient noble metal catalyst development for HER and emphasizing precise mapping between preparation, microstructure, and performance.