Protruding Pt single-sites on hexagonal ZnIn 2 S 4 to accelerate photocatalytic hydrogen evolution.

Single-site cocatalysts engineered on supports offer a cost-efficient pathway to utilize precious metals, yet improving the performance further with minimal catalyst loading is still highly desirable. Here we have conducted a photochemical reaction to stabilize ultralow Pt co-catalysts (0.26 wt%) onto the basal plane of hexagonal ZnIn 2 S 4 nanosheets (Pt SS -ZIS) to form a Pt-S 3 protrusion tetrahedron coordination structure. Compared with the traditional defect-trapped Pt single-site counterparts, the protruding Pt single-sites on h-ZIS photocatalyst enhance the H 2 evolution yield rate by a factor of 2.2, which could reach 17.5 mmol g -1 h -1 under visible light irradiation. Importantly, through simple drop-casting, a thin Pt SS -ZIS film is prepared, and large amount of observable H 2 bubbles are generated, providing great potential for practical solar-light-driven H 2 production. The protruding single Pt atoms in Pt SS -ZIS could inhibit the recombination of electron-hole pairs and cause a tip effect to optimize the adsorption/desorption behavior of H through effective proton mass transfer, which synergistically promote reaction thermodynamics and kinetics.