Creation of a facile heterojunction in Co/ZnO–TiO2 for the photocatalytic degradation of alizarin S

Abstract

Advanced oxidative process is an efficient method to photocatalytically degrade the effluent pollution by organic dyes with a suitable catalyst. Photocatalysts with a heterojunction not only improve the excitation efficiency of the catalyst in the presence of light by broadening the wavelength range of absorption but also reduce the rate of recombination. ZnO and TiO₂ were successfully synthesized in this study via solution combustion synthesis. Wurtzite ZnO was grown along with anatase TiO₂ to create a heterojunction of ZnO–TiO₂, and Co loading was carried out to improve the rate of electron transfer between the heterojunction for enhanced photocatalytic activity. The photogenerated electrons are injected from the conduction band of ZnO to TiO₂via Co to create ˙O²⁻ and holes from TiO₂ to form OH˙, which help to degrade alizarin S. The detailed photocatalytic experiment confirmed Co/ZnO–TiO₂ as an extremely efficient catalyst, which shows the complete degradation of the dye alizarin S in just 40 minutes under UV light illumination.