Engineering a Self-Grown TiO2 /Ti-MOF Heterojunction with Selectively Anchored High-Density Pt Single-Atomic Cocatalysts for Efficient Visible-Light-Driven Hydrogen Evolution

Abstract

A photocatalyst TiO₂ /Ti-BPDC-Pt is developed with a self-grown TiO₂ /Ti-metal-organic framework (MOF) heterojunction, i.e., TiO₂ /Ti-BPDC, and selectively anchored high-density Pt single-atomic cocatalysts on Ti-BPDC for photocatalytic hydrogen evolution. This intimate heterojunction, growing from the surface pyrolytic reconstruction of Ti-BPDC, works in a direct Z-scheme, efficiently separating electrons and holes. Pt is selectively anchored on Ti-BPDC by ligands and is found in the form of single atoms with loading up to 1.8 wt %. The selective location of Pt is the electron-enriched domain of the heterojunction, which further enhances the utilization of the separated electrons. This tailored TiO₂ /Ti-BPDC-Pt shows a significantly enhanced activity of 12.4 mmol g^-1 h^-1 compared to other TiO₂ - or MOF-based catalysts. The structure-activity relationship further proves the balance of two simultaneously exposed domains of heterojunctions is critical to fulfilling this kind of catalyst.

Keywords: Charge Transfer; Heterojunction; MOFs; Photocatalysis; Structure-Activity Relationship.