Plasmon-enhanced visible light photoelectrochemical and photocatalytic activity of gold nanoparticle-decorated hierarchical TiO2/Bi2WO6 nanorod arrays

Abstract

In this study, we show that the poor visible light photoelectrochemical (PEC) and photocatalytic activities of both wide-bandgap TiO2 and small-bandgap Bi2WO6 photocatalysts can be remarkably enhanced by constructing hierarchical Bi2WO6 nanosheet-wrapped TiO2 nanorod arrays (NRAs). X-ray photoelectron spectroscopy (XPS) measurements give direct experimental evidence for the establishment of a type II band alignment, which realizes visible light PEC performance of heterogeneous architecture through the transfer of photoexcited electrons from Bi2WO6 to TiO2. Moreover, Au nanoparticles (NPs) grown on the hierarchical Bi2WO6 nanosheets of TiO2/Bi2WO6 NRAs drastically enhance visible light PEC and photocatalytic activity of heterogeneous architectures because of surface plasmon resonance (SPR) effect. Benefiting from the synergistic effect of the type II band alignment and SPR effect, the hierarchical TiO2/Bi2WO6/Au NRAs achieve a photocurrent density of 29 μA cm−2, 11 times higher than that of TiO2 NRAs and 2.6 times as high as that of hierarchical TiO2/Bi2WO6 NRAs at 1 V vs Ag/AgCl. The hierarchical TiO2/Bi2WO6/Au NRAs exhibit remarkable stability in 2 h of light illumination. Additionally, the hierarchical TiO2/Bi2WO6/Au architectures show a significantly enhanced photocatalytic degradation for methyl blue (MB) molecules with a photodegradation of 91.5%. The study sheds new light on constructing visible light photocatalyst by forming the type II band alignment and integrating SPR effect.