Preparation and activity evaluation of n-p CuO/CeO2ZrO2 heterojunction photocatalyst for degradation of organic azo dye in wastewater under visible light irradiation

In this paper, n-p CuO/CeO2ZrO2 heterojunction photocatalysts with different concentrations of p-CuO were prepared by an auto solution combustion method. The structural and optical properties of the photocatalyst were characterized by X-ray powder diffraction (XRD), X-ray spectrum (EDS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the photocatalyst was evaluated by the degradation of an aqueous azo dye acid orange 7 (AO7) solution. Experiments were carried out to asset the effect of n-CuO loaded on the n-CeO2ZrO2 photocatalytic properties and determine the adsorption potential of azo dye on p-CuO/n-CeO2ZrO2 at different pH values. Potential degradation pathway for photocatalytic degradations has been proposed using some radical scavengers to evaluate intermediates. Under similar visible light conditions, the photodegradation rate of dye catalyzed by p-n CuO/ CeO2ZrO2 was much faster than that of n-type CeO2ZrO2. The sample with a p-n CuO/CeO2ZrO2 ratio of 0.021 presented the best photocatalytic activity, which was 35% higher than that of n-CeO2ZrO2.