Fig. 4

Comparison to the TiO2(P25)-Cu2O hybrid catalysts. a TEM image of the TiO2(P25)-Cu2O hybrid structure. The scale bar represents 20 nm. b XPS spectrum of the TiO2(P25)-Cu2O hybrid structure in the region of Cu 2p3/2. c Amounts of H2 (blue triangle), CH4 (black square), and CO (red circle) production using the TiO2(P25)-Cu2O catalysts as a function of the irradiation time. d Selectivity of gas products using ZnO-Cu2O (left) and TiO2(P25)-Cu2O (right) catalysts