Gold-nanoparticle-modified TiO2 nanowires for plasmon-enhanced photocatalytic CO2 reduction with H2 under visible light irradiation

Gold-nanoparticles (Au-NPs) incorporated TiO2-nanowires (TiO2-NWs) of controlled sizes prepared via hydrothermal and chemical reduction method have been investigated for CO2 photoreduction with H-2 under visible light irradiations. The nanocatalysts have been characterized by XRD, FESEM, TEM, N-2 adsorption-desorption, XPS, UV-vis and PL spectroscopy. Highly crystalline TiO2 nanowires of mesoporous structure were obtained in Au-deposited TiO2 NWs. Au-NPs, uniformly distributed over TiO2-NWs as Au-metal state, hindered charges recombination rate and increased TiO2 activity under visible light through plasmon excitation. With the deposition of Au-NPs, the efficiency of CO2 reduction to CO was greatly enhanced under lower energy visible light irradiations. The maximum CO and CH3OH yield rate over 0.5 wt.% Au-NPs/TiO2 NWs reached to 1237 and 12.65 mu mole g catal.(-1) h(-1), respectively. High quantum yield was also observed over Au-NPs/TiO2 NWs using H-2 as reductant. The significantly improved photoactivity was evidently due to efficient electron-hole separation and surface plasmon response of Au-NPs. The reaction-pathway is proposed to provide insights over the mechanism of Au-plasmon-enhanced CO2 conversion. (C)2015 Elsevier B.V. All rights reserved.