Preparation and characterization of noble metal (Pt, Ag, Ru) loaded ZnGa2O4 and its photocatalytic and photoelectric performance

ZnGa2O4 nanoparticles were prepared by hydrothermal method. Noble metal (Pt, Ag, Ru) nanoparticles were subsequently selected as cocatalyst for ZnGa2O4 surface modification by photo-deposition method. XRD, SEM, TEM, HRTEM, UV–vis DRS and PL techniques were used for crystalline structure, morphology, composition, light absorption and charge separation analysis, respectively. The deposition of cocatalyst (Pt, Ag, Ru) enhanced the visible light absorption and improved the electrons and holes separation. The photocatalysts were investigated in the photocatalytic reduction of CO2 with H2O containing NaOH and Na2SO3 as sacrificed agent under the simulated sunlight irradiation. The highest photocatalytic efficiency was observed over 1 wt% Pt/ZnGa2O4, and the yield of the main reduction products, methanol, was 3.72 mmol gcat−1 under 120 min light irradiation, which was 4.3 times as compared to the unloaded ZnGa2O4. The photoelectric properties of ZnGa2O4 and 1 wt% Pt/ZnGa2O4 samples were also detected. The transient photocurrents of 1 wt% Pt/ZnGa2O4 sample are remarkably higher than that of unloaded ZnGa2O4. A possible mechanism of photocatalytic reduction of CO2 over Pt/ZnGa2O4 was proposed.