Investigation on the surface charge separation in Pt-supported morphology-related-TiO2 and its effect on water splitting

Abstract

Lowering Pt loading in the catalyst while maintaining its superior catalytic efficiency during hydrogen evolution reaction (HER) is essential for the large-scale application of water splitting. The utilization of strong metal-support interaction (SMSI) through morphology engineering has emerged as an effective strategy in fabricating Pt-supported catalysts. However, a simple and explicit routine to realize the rational design of morphology-related SMSI remains challenging. Here we report a protocol for the photochemical deposition of Pt, which benefits from the intrinsic difference in absorption capability of TiO2 to establish proper Pt+ species and charge separation domains on the surface. With a comprehensive investigation of the surface environment through experiments and Density functional theory (DFT) calculations, charge transfer from Pt to Ti, the separation of electron-hole pairs, and the enhanced electron transfer in the TiO2 matrix were confirmed. It is reported that H2O molecules can be spontaneously dissociated by the surface Ti and O, generating OH stabilized by adjacent Ti and Pt. Such adsorbed OH group induces changes in the electron density of Pt, consequently favours the H adsorption and enhances the HER. Benefiting from the preferable electronic state, the annealed Pt@TiO2-pH9 (PTO-pH9@A) exhibits an overpotential of 30 mV to reach 10 mA cm−2 geo and a mass activity of 3954 A g-1Pt, which is 17-fold higher than the commercial Pt/C. Our work provides a new strategy for the high-efficient catalyst design by the surface state- regulated SMSI.