CuCr2O4/TiO2 heterojunction for photocatalytic H2 evolution under simulated sunlight irradiation

Abstract CuCr 2 O 4 /TiO 2 heterojunction has been successfully synthesized via a facile citric acid (CA)-assisted sol–gel method. Techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–vis diffuse reflectance spectrum (UV–vis DRS) have been employed to characterize the as-synthesized nanocomposites. Furthermore, photocatalytic activities of the as-obtained nanocomposites have been evaluated based on the H 2 evolution from oxalic acid solution under simulated sunlight irradiation. Factors such as CuCr 2 O 4 to TiO 2 molar ratio in the composites, calcination temperature, photocatalyst mass concentration, and initial oxalic acid concentration affecting the photocatalytic hydrogen producing have been studied in detail. The results showed that the nanocomposite of CuCr 2 O 4 /TiO 2 is more efficient than their single part of CuCr 2 O 4 or TiO 2 in producing hydrogen. The optimized composition of the nanocomposites has been found to be CuCr 2 O 4 ·0.7TiO 2 . And the optimized calcination temperature and photocatalyst mass concentration are 500 °C and 0.8 g l −1 , respectively. The influence of initial oxalic acid concentration is consistent with the Langmuir model.