A new hetero-junction p-CuO/Al2O3 for the H2 evolution under visible light

This study was undertaken to assess the potentiality of the hetero-junction p-CuO/Al2O3 (20/80) for the photochemical hydrogen liberation. The catalysts, synthetized by nitrate route at 400 degrees C, were characterized by thermal analysis, X-ray diffraction, electrical properties and photo-electrochemistry. The hetero-junction was synthesized at 400 degrees C, to preclude the formation of the spinel CuAl2O4. A forbidden band of similar to 1.32 eV was determined from the diffuse reflectance of CuO. The capacitance-potential (C-2 - E) plot, plotted at neutral (pH similar to 7) is characteristic of p-type behavior with a flat band of +0.60 V-SCE. Therefore, the potential of the conduction band (CB) of CuO (-0.42 V-SCE), made up mostly from Cu2+: eg orbital, is more cathodic than that of H-2 level, leading to the feasibility of H-2 evolution upon visible light illumination (2.09 x 10(19) photons/s). The best performance with H-2-liberation rate of 68 mu mol (g catalyst)(-1) min(-1) was obtained in NaOH electrolyte (0.1 M) in presence of S2O32- (10(-2) M) as sacrificial agent, leading to a quantum efficiency of 0.37%. More interestingly, the photoactivity was improved during the second cycle. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.