Preparation and Characterization of p-n Heterojunction Photocatalyst Cu2O/In2O3 and its Photocatalytic Activity under Visible and UV Light Irradiation

The photocatalyst In2O3 was prepared from indium hydroxide calcined at 500 degrees C for 3 h. The p-n heterojunction photocatalyst Cu2O/In2O3 was prepared by ballmilling through doping Cu2O into In2O3 and using absolute alcohol as a disperser. The photocatalyst was characterized by X-ray powder diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, terephthalic acid photoluminescence probing technique, photoluminescence emission spectra, and transmission electron microscopy. The results showed that the photocatalytic activity of the Cu2O/In2O3 was much higher than that of In2O3 on the photocatalytic reduction of Cr2O72-. However, the photocatalytic activity was much lower than that of In2O3 on the photocatalytic oxidation of methylene blue. Namely, Cu2O/In2O3 has higher photocatalytic reduction activity but lower photocatalytic oxidation activity. For the photocatalytic reduction of Cr2O72-, the optimum amount of doped Cu2O is 0.5 wt %. Compared with pure In2O3, the photoabsorption wavelength range of the photocatalyst redshifts and improves the utilization of the total spectrum. The effect of ballmilling time on the photocatalytic activity was investigated. The mechanisms of influence on the photocatalytic activity were also discussed by the p-n junction principle and the valance band theory. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3489945] All rights reserved.