The synergy between Ti species and g-C3N4 by doping and hybridization for the enhancement of photocatalytic H2 evolution

Abstract

A Ti species modified g-C₃N₄ photocatalyst was synthesized via an in situ hydrothermal route and the subsequent low-temperature calcination. The hydrothermal process results in not only the fabrication of TiO₂/g-C₃N₄ heterojunctions, but also the coordination between Ti species and g-C₃N₄, which are verified by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrical resistance test confirms that the coordination can improve the electrical conductivity of composites and can make the charge transfer easier. The photoluminescence (PL) and photocurrent measurements exhibit that the hybridization enhances the separation efficiency of photo-induced electrons and holes. As a result, the Ti species modified g-C₃N₄ photocatalysts exhibit much higher photocatalytic H₂ evolution than the simple heterojunction of TiO₂/g-C₃N₄ obtained via a microwave method and the mechanical mixture of TiO₂ and g-C₃N₄ under visible-light irradiation. The coordination mechanism and synthesis route of TiO₂/g-C₃N₄ heterojunctions are proposed.