| Popis: |
The hetero-junction 5% CuO/ZnO elaborated by co-precipitation is studied by thermal analysis, X-ray diffraction, ATR spectroscopy, and optical reflectance to assess its performance for the H2 photoproduction. The specific surface area averages ~7 m2 g−1 while the crystallite size varies from 20 to 50 nm. The diffuse reflectance spectra shows an indirect transition at 3.13 eV for ZnO and a direct transition at 1.60 eV for CuO. The capacitance-potential plot of the sensitizer CuO exhibits p-type conduction, due copper deficiency, with a flat band potential of 0.075 VSCE. ZnO works as an electron bridge; its conduction band of ZnO (−0.68 VSCE) is cathodically localized with respect to that of CuO and CuOH2O/H2 level (~−0.5 VSCE), yielding H2 evolution under visible light illumination. H2 liberation rate of 340 µmol h−1 (g catalyst)−1 and a quantum yield of 0.38% were obtained under full light (27 mW cm−2) for a catalyst dose of 0.25 mg/mL and pH ~ 7 in presence of \({{\text{SO}}_{3}}^{2 - }\) as reducing agent; H2 liberation rate of 340 µmol h−1 (g catalyst)−1 and a quantum yield of 0.38% are determined. |
