1 Photoelectrochemical Water Splitting Nanoporous GaN Three-electrode cell System Three-electrode cell System Three-electrode cell System Effects by: Surface to voluem maximum → increased active site Reconstruction of band structure and surface composition Nanostructure CuO Schematic diagram PEC characteristics Effects by: Double side photoelectrode → improve efficiency Facile process and scalable Light-Driven HER Based on Core-Shell Photocatalysts Au@CeO2 core-shell Simulation structure Optimized structure Effects by: Surface plasmon Core-shell unique properties N-CeO2 graphene core-shell Simulation structure Optimized structure Effects by: Nitrogen dopant Graphene conductivity Core-shell unique properties Au@CeO2@graphene Simulation structure Why photocataysis: Cost-effentiveness Simple strategy High effciency Applications: Water splitting H2 generation CO2 reduction Gas sensing