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

CuCr2O4/TiO2 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 H2 evolution from oxalic acid solution under simulated sunlight irradiation. Factors such as CuCr2O4 to TiO2 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 CuCr2O4/TiO2 is more efficient than their single part of CuCr2O4 or TiO2 in producing hydrogen. The optimized composition of the nanocomposites has been found to be CuCr2O4·0.7TiO2. 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.