Biaxial Strain-Engineered Pt-Sulfur Vacancy Dual Active Sites in Pt/MoO₂@MoS₂ Architectures for pH-Universal Hydrogen...

Developing high-performance pH-universal hydrogen evolution reaction (HER) catalysts is severely hindered by the conflicting kinetic requirements of proton reduction in acidic media and sluggish water dissociation in nonacidic environments. Here, we report an interfacial engineering strategy to construct Pt decorated core-shell MoO₂@MoS₂ (Pt/MoO₂@MoS₂) architectures featuring biaxial-strain-regulated Pt-sulfur vacancy (S_v) dual active sites to overcome these barriers. The catalyst exhibits ultralow overpotentials of 36, 60, and 74 mV at 10 mA cm^-2 in acidic, alkaline, and neutral media, respectively, along with outstanding long-term stability (sustaining at least 1000 h of continuous operation at 100 mA cm^-2 in acids). Combining with density functional theory calculations, we reveal that interfacial strain facilitates S_v formation and, together with S_v, synergistically stabilizes Pt anchoring. Within this architecture, Pt clusters serve as the primary active centers for H* adsorption in acids and dominate the H₂O adsorption/dissociation processes in alkaline/neutral environments. Crucially, the adjacent S_v sites act as dedicated desorption channels, facilitating hydrogen migration and recombinative release across the broad pH range. This synergistic configuration optimizes the HER pathway by preventing the excessive occupation of Pt sites, thereby ensuring rapid kinetics and exceptional performance. This work provides a compelling atomic-scale design principle for developing highly efficient and durable pH-universal electrocatalysts.