Gold-Titanium Dioxide Half-Dome Heterostructures for Plasmonic Hydrogen Evolution

Abstract

Plasmonic water splitting gains increasing attention due to their broad absorption spectra and excellent chemical stability. However, plasmonic water splitting suffers from low efficiency due to difficulties of utilizing plasmonic energetic charge carriers. Structural factors need to be carefully examined to overcome the short lifetime of plasmonic hot carriers. Here we investigate Au/TiO2 half-dome patterns as a plasmonic photoelectrode to examine the effects of incident light angle and orientation of nanostructures on photochemical hydrogen evolution. Half-dome structures exhibit 4- and 3-fold higher photocurrent density and photovoltage, respectively, than a flat thin film. The enhanced photoreactivity is ascribed to the increased angle between the Au/TiO2 interface and the electric field of irradiated light. The result indicates that the kinetic momentum of the incident photon can significantly contribute to hot electron injection and reaction rate. The monolithic Au/TiO2/Pt half-dome structures are also constructed to show sustainable hydrogen evolution without external bias under visible light illumination.