Visible light in situ driven electron accumulation at the Ti–Mn–O3 sites of TiO2 hollow spheres for photocatalytic hydrogen production

Abstract

The application of electron-accumulation sites in the photocatalytic splitting of water for the hydrogen-production process represents a prospective strategy for the efficient use of solar energy. Herein, electron-accumulation sites (Ti–Mn–O₃) anchored on TiO₂ hollow spheres (THS) were facilely prepared by a two-step calcination method involving the modification of Mn species and surface oxygen vacancies (Ovs). The optimized photocatalyst (TM30) showed excellent activity for photocatalytic water splitting (λ ≥ 420 nm). The Ti–Mn–O₃ sites that were constructed on the surface of THS owing to electron transfer from the Mn atom to the Ti atom and three O atoms around Ovs were rich in electrons under in situ visible-light-driven conditions and constituted electron-accumulation sites, which not only greatly regulated the surface potential and band gap to enhance the separation efficiency of photogenerated charge carriers and the visible-light-responsive capability of the compound, but also improved the dissociation for the adsorption of H₂O to reduce Gibbs free energies for hydrogen adsorption as well. This study demonstrates a novel approach for the efficient use of solar energy to produce hydrogen toward water splitting.