Au@SiO₂ core/shell nanoparticle-decorated TiO₂ nanorod arrays for enhanced photoelectrochemical water splitting

To improve the separation efficiency of photoinduced charge carries, Au@SiO₂ nanoparticles (NPs) with core-shell structure were loaded onto the surface of TiO₂ nanorods grown on fluorine-doped tin oxide substrate by a facile two-step process. The resulted Au@SiO₂/TiO₂ photoanodes were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, as well as photoelectrochemical measurements. Compared with pristine TiO₂ nanorod film, the Au@SiO₂/TiO₂ films showed remarkable enhancement in photoelectrochemical water splitting, with incident photon-to-current conversion efficiency increasing from 31 % to 37 % at 380 nm at 0.7 V versus saturated calomel electrode. This could be interpreted by the effect of metallic surface plasmon resonance of Au@SiO₂ NPs, which would generate an intense electromagnetic field with spatially nonhomogenous distributed intensity. As a result, the charge carriers generated in the near-surface region of TiO₂ nanorods could be easily separated. This modification method based on the effect of metallic surface plasmon resonance for promoted charge carrier separation provides a promising way to develop semiconductor photoelectrodes with high solar water-splitting performance.