Graphene-induced formation of visible-light-responsive SnO₂-Zn₂SnO₄ Z-scheme photocatalyst with surface vacancy for the enhanced photoreactivity towards NO and acetone oxidation

As a ternary complex oxide with good physic-chemical stability, Zn₂SnO₄ is a promising candidate in the photocatalytic application. However, the photocatalytic activity of Zn₂SnO₄ needs further to improve due to its wide bandgap (about 3.4 eV) and intrinsic high recombination rate of photo-generated charge carriers. In this paper, the positive influence of graphene on the structure and visible photocatalytic activity of Zn₂SnO₄ in oxidation of NO and acetone was systematically investigated based on the fact that graphene has the property of high electronic conductivity for transporting and storing electrons. It was found that the presence of graphene not only induces the formation of SnO₂, but also introduces Sn vacancy, which can trigger the visible light photocatalytic activity. The photocatalyst loading with 3.0 wt% of graphene shows the highest photocatalytic reactivity towards oxidation of NO and acetone under visible light illumination. Graphene can efficiently transfer the photo-produced electrons from the conduction band of Zn₂SnO₄, retarding the recombination of carriers and therefore enhancing the visible photo-reactivity. A visible-light-responsive photocatalytic reaction model based on the three-component-photocatalyst SnO₂- Zn₂SnO₄ /graphene was put forward. Copyright © 2017 Elsevier B.V. All rights reserved.