Two-Dimensional\nTopological Platinum Telluride Superstructures\nwith Periodic Tellurium Vacancies for Efficient and Robust Catalysis

Defect engineering in the inherently inert basal planes\nof transition\nmetal dichalcogenides (TMDs), involving the introduction of chalcogen\nvacancies, represents a pivotal approach to enhance catalytic activity\nby exposing high-density catalytic metal single-atom sites. However,\nachieving a single-atom limit spacing between chalcogen vacancies\nto form ordered superstructures remains challenging for creating uniformly\ndistributed high-density metal single-atom sites on TMDs comparable\nto carbon-supported single-atom catalysts (SACs). Here we unveil an\nefficient TMD-based topological catalyst for hydrogen evolution reaction\n(HER), featuring high-density single-atom reactive centers on a few-layer\n(7 × 7)-PtTe<sub>2–<i>x</i></sub> superstructure.\nCompared with pristine Pt(111), PtTe<sub>2</sub>, and (2 × 2)-PtTe<sub>2–<i>x</i></sub>, (7 × 7)-PtTe<sub>2–<i>x</i></sub> exhibits superior HER performance owing to its substantially\nincreased density of undercoordinated Pt sites, alongside exceptional\ncatalytic stability when operating at high current densities. First-principles\ncalculations confirm that multiple types of undercoordinated Pt sites\non (7 × 7)-PtTe<sub>2–<i>x</i></sub> exhibit\nfavorable hydrogen adsorption Gibbs free energies, and remain active\nupon increasing hydrogen coverage. Furthermore, (7 × 7)-PtTe<sub>2–<i>x</i></sub> possesses nontrivial band topologies\nwith robust edge states, suggesting potential enhancements for HER.\nOur findings are expected to advance TMD-based catalysts and exploration\nof topological materials in catalysis.