The enhanced water splitting photocurrent has been observed through plasmonic mesoporous composite electrode TiO2–CMK-3/Ag under visible light irradiation. Strong light absorption achieved from the integrations of ordered mesoporous carbon (CMK-3) and silver plasmonic nanoparticles (NPs) layer in the TiO2, which significantly increased the effective optical depth of TiO2–CMK-3/Ag photoelectrode. The carbon-based CMK-3 also increased the surface wetting behavior and conductivity of the photoelectrodes, which resulted in a higher ion exchange rate and faster electron transport. The synthesis of high crystalline TiO2–CMK-3/Ag composite photocatalyst was verified by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Pronounced enhancement of light absorption of TiO2–CMK-3/Ag photoelectrode was confirmed by UV/vis spectrophotometers. Two orders of magnitude of the enhanced water splitting photocurrent were obtained in the TiO2–CMK-3/Ag composite photoelectrode with respect to TiO2 only. Finally, spatially resolved mapping photocurrents were also demonstrated in this study.
