Enhanced Photoelectrocatalytic Activity of Methanol Oxidation on TiO2-Decorated Nanoporous Gold

Au-TiO2 nanocomposites have been widely investigated for their potential applications in solar energy conversion, CO oxidation, and methanol reforming reactions. In this study, commercial TiO2 nanoparticles were assembled on the surface of nanoporous gold (NPG) to fabricate novel TiO2/NPG nanocomposite electrodes. Electrochemical and photoelectrochemical techniques were used to investigate the characteristics of the electrodes. Large photocurrent and nearly reversible voltammetric responses were observed for methanol photoelectrocatalysis under UV radiation, indicating an effective elimination of gold surface passivation due to a pronounced synergistic effect between TiO2 and NPG. A possible mechanism was proposed to elucidate such a synergistic effect, which is based on the reaction of the photogenerated reactive intermediates on the surface of NPG. Kinetic studies showed that the coupling of TiO2 with NPG in our system could lead to about a 30% decrease of apparent activation energy for methanol electrooxidation.