A Near-Perfect Pt Cocatalyst with a Spatially Oriented Distribution of Pt/Pt for Photocatalytic Water Splitting.

Loading the cocatalyst, e.g., Pt, is a promising strategy for photocatalytic overall water splitting, in which metallic state Pt° facilitates proton reduction and positive valence state Pt inhibits H/O recombination. However, simultaneously leveraging the advantages of Pt and Pt in Pt-photocatalyst hybrids for photocatalytic water splitting is challenging. Herein, a universal strategy is demonstrated for modulating Pt valence state, obtaining a spatially oriented distribution of Pt/Pt and a close to zero proton reduction barrier, along with isolated O adsorption. As a proof of concept, Pt undergoes electron transfer to ZnInS, accompanied by partial oxidation from Pt to Pt through the introduction of electron-deficient centers in ZnInS via vanadium doping and sulfur vacancy (V-Sv-ZIS). Reverse electron transfer induces Pt dominating 83% of the region near the Pt/V-Sv-ZIS interface and Pt dominating in the remaining 17% near the Pt cluster center, which can be extended to other Pt-based catalyst systems. The dominant Pt inhibits O adsorption and induces the lowest H/O recombination rate of 4%, and the minimal Pt obtains a 152.2-fold increase in photogenerated electron density, ultimately realizing a 45.4-fold increase in photocatalytic activity. A 10 m large-area photocatalytic system is fabricated, producing 6.4 L of H per day under natural sunlight.