Plasmon-enhanced light energy conversion using gold nanostructured oxide semiconductor photoelectrodes

We have successfully demonstrated plasmon-enhanced photocurrent generation using gold nan-oparticle- loaded titanium dioxide single-crystal (TiO2) photoelectrodes with visible-light irradiation. Water molecules serve as an electron source in photocurrent generation, and oxygen evolution occurs due to water oxidation from a gold nanostructured TiO2 photoelectrode as a half reaction of water splitting. On the basis of this property, the photocurrent generation system was applied to the plasmon-induced water-splitting system using both sides of the same strontium titanate (SrTiO3) single-crystal substrate without an electrochemical apparatus. The chamber on the side of the gold nanoparticles was the anode side, whereas the chamber on the side of the platinum plate was the cathode side. Platinum was used as a co-catalyst for hydrogen evolution. Hydrogen and oxygen were separately evolved from the anode and cathode chambers, respectively. Water splitting was induced with a relatively low chemical bias of 0.23 V due to plasmonic effects based on efficient water oxidation. Similar to the artificial photosynthesis system, we have also demonstrated ammonia formation via nitrogen fixation using ruthenium as a co-catalyst via an analogous setup of the water-splitting system.