Facile hydrothermal preparation of a ZnFe2O4/TiO2 heterojunction for NOx removal

Abstract

Titanium dioxide (TiO2) has become the most promising photocatalyst. It is non-toxic and has a wide range of sources, but its application is limited due to its weak visible light absorption capacity. Compounding with other materials to form heterojunctions has proven to be effective strategies for enabling high photocatalytic performances under visible light. Here, the ZnFe2O4/TiO2 composites had been synthesized by a facile hydrothermal method to realize efficient visible light photocatalytic activity of NOx removal. A series of characterizations, such as XRD, ESR, in-situ DRIFTS, etc., were used to analyze the physical and chemical properties of the photocatalyst, which demonstrated that the composite material had more active sites and a faster electron transfer rate. The optimal sample (12 wt% ZnFe2O4/TiO2) had a NOx removal rate of 54 % nearly 11 times higher than that of original TiO2. On the basis of the above photocatalytic experimental results and characterizations, a possible mechanism or pathway was proposed and illustrated. This work can provide a feasible strategy to prepare TiO2-based composite materials with magnetic separation properties to effectively remove NOx.