La and Cr Co-doped SrTiO3 as an H2 evolution photocatalyst for construction of a Z-scheme overall water splitting system

Abstract

The photocatalytic activity of a semiconductor-based photocatalyst largely depends on the semiconductor's intrinsic crystal and electronic properties. We have prepared two types of La and Cr co-doped SrTiO3 photocatalysts (SrTiO3(La,Cr)) using the polymerized complex method (PCM) and sol-gel hydrothermal method (SHM). Under λ > 420-nm visible light irradiation, only the Pt-loaded SrTiO3(La,Cr) prepared by the SHM showed efficient photocatalytic activities for both H2 evolution in the presence of an I− sacrificial reagent and for Z-scheme overall water splitting when it was coupled with the Pt-loaded WO3 in the presence of I− and IO3− as the shuttle redox mediator. The superior photocatalytic activity of SrTiO3(La,Cr) prepared by the SHM has been ascribed to its more negative conduction-band position, higher carrier concentration, and higher carrier mobility, demonstrating that the design and synthesis of an H2-evolution photocatalyst with appropriate electronic properties is crucial for achieving Z-scheme overall water splitting.