Interfacial coupling effects in g-C3N4/SrTiO3 nanocomposites with enhanced H2 evolution under visible light irradiation

The g-C3N4/SrTiO3 nanocomposite is an important material in photocatalysis, but little attention has been paid to their interfacial interaction in photocatalytic reaction. Herein, we prepare the g-C3N4/SrTiO3 nanocomposites via a two-step mechanically milling and calcination process. The composite exhibited the highest H2 evolution activity superior to that of the pure g-C3N4 and SrTiO3 in the visible light. The results of UV–vis DRS, PL and photoelectrochemical measurements demonstrated that g-C3N4/SrTiO3 exhibited more visible light adsorption and faster photo-generated charge transfer. Furthermore, the interfacial electronic structures of g-C3N4/SrTiO3 nanocomposites were thoroughly characterized. According to the XPS and DFT results, with the help of a strong built-in electric field presenting in the g-C3N4/SrTiO3 interface, the photo-generated electrons flow to the SrTiO3 from g-C3N4, leading to the highly-efficient electron separation and more H2O molecules photo-reduction to H2. This work explicates the significant role of built-in electric field in H2 evolution on g-C3N4/SrTiO3 photocatalyst.