Surface plasmon-driven photoelectrochemical water splitting of TiO 2 nanowires decorated with Ag nanoparticles under visible light illumination

Abstract Here, we demonstrate that TiO 2 nanowires (NWs) can be significantly driven by visible light through the decoration with Ag nanoparticles (NPs) (Ag-decorated TiO 2 NWs). The Ag-decorated TiO 2 NWs show remarkably photoelectrochemical (PEC) water splitting performance under illumination with λ > 420 visible light due to surface plasmon resonance (SPR) of Ag NPs. In this work, low power of the used light source (100 mW/cm 2 ) was not capable of heating the Ag-decorated TiO 2 nanowire photoanode enough to directly split water. In addition, under irradiation with λ > 420 nm visible light, no photocurrent was produced by TiO 2 nanowire photoanode indicates that electron transitions between valence band and conduction band do not take place in prepared anatase TiO 2 NWs. Meanwhile, the SPR energy (2.95–2.13 eV 2 NWs to generate electro-hole pairs through SPR-enhanced electromagnetic fields. Thus the remarkably visible-light-responsive PEC water splitting activity of Ag-decorated TiO 2 NWs is not attributed to local heating caused by SPR-mediated photothermal process, large enhancement of electromagnetic fields induced by SPR and scattering of resonant photons. We propose that the visible light PEC water splitting performance of Ag-decorated TiO 2 NWs is attributed to electron transfer from Ag NPs to the conduction band of TiO 2 NWs mediated by SPR. In addition, a Schottky barrier established at the interface of Ag NPs and TiO 2 NWs prevents these transferred electrons from returning to the Ag NPs and significantly retarded the recombination of electron-hole pairs in the Ag NPs, also contributing to visible-light-driven PEC water splitting performance. So the remarkably visible-light-driven PEC water splitting performance of Ag-decorated TiO 2 NWs is attributed to the synergistic effects of electron transfer mediated by SPR and the Schottky barrier between Ag NPs and TiO 2 NWs. The achieved Ag-decorated TiO 2 NWs can be added to these previously prepared TiO 2 photocatalysts mainly driven by SPR of Au NPs for the development of new visible light photocatalysts.