By loading 1 wt%
RuO2 as cocatalyst, the meso-ZnGa2O4 shows higher photocatalytic
activity for reduction of CO2 into CH4 than ZnGa2O4 obtained
by solid state reaction (SSR), owing to strong gas adsorption by
the mesostructure and more reaction sites arising from high specific
surface area (SBET = 110.4 m2 g−1 for meso-ZnGa2O4 and 4.6
m2 g−1 for SSR-ZnGa2O4).