Yeast Reduced Ti³⁺ Self-Doped SrTiO₃/rGO-In-Ni₂P Nanocomposite for Efficient Visible Light-Driven Hydrogen Generation

Abstract

SrTiO 3 is a promising candidate for photocatalysis because of its tunable band structure and extreme stability. By suitably formulating nanocomposites of SrTiO 3 with other materials, it can introduce defects into the crystal lattice and thereby alter its electronic structure favorably for the desired catalytic applications. In this study, a ternary composite in the form of a coating comprising of SrTiO 3 nanocubes on yeast-reduced graphene oxide (yrGO) and Ni 2 P is developed for the generation of hydrogen by visible light-driven water splitting. The in situ tuning on the electronic state of SrTiO 3 nanocubes by a self-doping effect from the controlled and simultaneous occurrence of Ti 3+ species and oxygen vacancies via the Ti−C bond formation is achieved in the presence of a yeast-assisted reduction of GO in the SrTiO 3 /yrGO nanocomposite. Consequently, SrTiO 3 forms epitaxially self-assembled SrTiO 3 nanocubes on the surface of yrGO as a distinctive bush-like structure, which is further integrated with Ni 2 P matrix resulting in a hierarchical architecture consisting of SrTiO 3 /yrGO microflowers on the spherical Ni 2 P beds. This harmonious integration of SrTiO 3 /yrGO on Ni 2 P enriches the catalytically active sites facilitated by yrGO together with a straddling band gap alignment in the heterojunction for the efficient separation of the electron−hole pairs. The SrTiO 3 /yrGO-Ni 2 P composite coating heterojunction exhibits an outstanding performance toward solar light-driven water splitting and produces 13.25 mmol/g/h of hydrogen with an AQE value of 36.26% under 1 h irradiation after a successful compositional tuning on the coating surface.