Plasmon-Enhanced Photocurrent Generation and Water Oxidation with a Gold Nanoisland-Loaded Titanium Dioxide Photoelectrode

Metallic nanoparticles showing localized surface plasmon resonance (LSPR) are efficient elements in the localization of light to nanometer-scale regions and enhance the light matter interaction. We show that gold nanoisland (Au-NI)-loaded titanium dioxide (TiO2) photoelectrodes exhibited plasmon-enhanced photocurrent generation in the visible wavelength region, and the photocurrent action spectrum was corresponding to the LSPR band. The photocurrent enhancement may result from the plasmon-assisted electron transfer reaction from Au NI to TiO2. A hole with high oxidation ability was left at the TiO2 surface states near the Au-NIs/TiO2 interface, which has the potential for photocatalytic water oxidation. The photocurrent generation efficiency of Au-NIs/TiO2 photoelectrode is highly dependent on the annealing temperature for the preparation of Au-NIs. High-resolution transmission electron microscopy and electron energy-loss spectroscopy analyses show that the interfacial structure between Au NI and TiO2 plays a crucial role in the photocurrent generation efficiency and photocatalytic ability.