Ligand-exchange assisted preparation of plasmonic Au/TiO2 nanotube arrays photoanodes for visible-light-driven photoelectrochemical water splitting

Visible-light-driven responsive Au/TiO2 nanotube arrays nanocomposites (LE-Au/TNTs) are prepared by depositing self-assembled monolayer of 3-mercaptopropionic acid (MPA) inside TNTs and then removing the ligands on the surface of Au through direct ligand-exchange method, which is beneficial for formation of intimate Au/TNTs Schottky contact after a mild annealing process. Under visible light illumination (lambda > 400 nm), the photocurrent density of LE-Au/TNTs is 202 mu A/cm(2), which is the highest value ever reported in Au/TiO2 systems. Moreover, the incident photon to current conversion efficiency (IPCE) of LE-Au/TNTs at surface plasmonic resonance induced absorption peak (555 nm) is 7.4%. It is worth noted that the hydrogen evolution rates of the LE-Au/TNTs under simulated solar irradiation (AM1.5G, 100 mW/cm(2)) are 22.5 mu mol/h, which is much higher than that of pristine TNTs (8.1 mu mol/h). In addition, the LE-Au/TNTs show higher photoelectrochemical water splitting performance than the Au/TNTs prepared by direct impregnation-precipitation (IPAu/TNTs) strategy, which is ascribed to the close Schottky contact between Au and TNTs for better charge separation and transfer. (C) 2015 Elsevier B.V. All rights reserved.