Preparation of Au/reduced graphene oxide/hydrogenated TiO2 nanotube arrays ternary composites for visible-light-driven photoelectrochemical water splitting

Visible-light-driven responsive Au/reduced graphene oxide/hydrogenated TiO2 nanotube arrays ternary composites (Au/RGO/H-TNTs) are constructed by electrophoretical deposition (EPD) of Au nanoparticles and graphene oxide sheets onto hydrogenated TiO2 nanotube arrays. Under visible light illumination (λ > 400 nm), the photoelectrochemical (PEC) current density and hydrogen evolution rate of Au/RGO/H-TNTs is 224 μA/cm2 and 45 μmol/cm2/h, which is much higher than that of pristine TNTs, H-TNTs and RGO/H-TNTs. The enhanced PEC activity of Au/RGO/H-TNTs ternary composites is attributed to (1) the outer layer of Au nanoparticles serves as photosensitizer for visible light harvesting due to the localized surface plasmon resonance effect, (2) the RGO middle layers act as excellent electron transporter which facilitating efficient separation of electron-hole pairs, and (3) the inner H-TNTs not only show certain visible light absorption due to its narrowed band gap, but also serve as electron collector and further transfer the electrons to counter electrode for hydrogen generation. The proposed PEC performance enhancement mechanism is further confirmed by electrochemical impedance spectroscopy and photoluminescence results. © 2015 Elsevier B.V.