TiO2 nanotube arrays (NTAs) has been widely reported as a promising material for applications in photoelectrochemical (PEC) water splitting due to its light confinement, high carrier mobility property, and large surface area. One of the major drawbacks of pure TiO2 is narrow range of optical response. A great of efforts have been devoted to expand TiO2 optical absorption spectrum into the visible region by band structure engineering or coupling with other components (e.g., dyes, noble metal, semiconductor quantum dots, etc.). In particular, nanostructures of some noble metal, especially gold (Au) have been attracting much attention because they can strongly interact with light in the visible region due to their localized surface plasmon resonance (LSPR) properties. In this work, we prepared Au-decorated TiO2 NTAs by carefully depositing Au nanoparticle on the surface of TiO2 NTAs. The morphology, crystallinity, elemental composition and light absorption capability of as-obtained Au-TiO2 NTAs were distinguished on various characterizations. The designed Au-TiO2 NTAs is expected to significantly increase the Au SPR intensity and consequently boost the hot electron injection, leading to a considerable enhanced water splitting performance compared to pristine TiO2 NTAs. To elucidate effect of SPR for accelerating water splitting reaction in visible light, monochromatic incident photon-to-electron conversion efficiency (IPCE) was measured. The increased photocurrent in visible region indicates that plasmon resonances arise from the collective oscillations of the electrons close to surface of the metal, and the plasmon-excited hot electrons in the Au can be transferred to the conduction band of TiO2 NTAs. We demonstrated that SPR-mediated hot electron injection leads to highly efficient and stable visible-light PEC activity. Furthermore, we controlled the resonance wavelength by changing the size of nanoparticles, which suggests that the entire solar spectrum can be exploited using the plasmonic-metal induced hot electrons.

Hot electron and surface plasmon-driven water splitting on Au nanoparticles/TiO2 nanotube arrays

253rd National Meeting (2017)

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