Pt(Cu) catalyst on TiO 2 powder support prepared by photodeposition-galvanic replacement method

A new kind of ternary Pt(Cu)/TiO2 catalyst was prepared by photodeposition of Cu on TiO2 powder support and subsequent galvanic deposition of Pt from a solution of K2PtCl6 salt. For its characterization energy-dispersive spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction were applied. The electrochemical and photoelectrochemical behavior of the platinized Cu/TiO2 catalyst with respect to methanol oxidation reaction (MOR) was evaluated by cycling potentiometric and chronoamperometric electrochemical measurements in darkness and under UV light irradiation. The electrocatalytic activity of the Pt(Cu)/TiO2 catalyst towards MOR was evaluated and compared to that of a commercial Pt/C catalyst. The inherent catalytic activity demonstrated by Pt(Cu)/TiO2 electrode was higher than the Pt/C catalyst and the specific mass activity was comparable. At low overpotential the current at the Pt(Cu)/TiO2 catalyst is further enhanced under UV light illumination. The improved behavior of Pt(Cu)/TiO2 is associated with effective dispersion and utilization of Pt due to several circumstances. It is prepared by galvanic displacement of photodeposited Cu and galvanic deposition on photoreduced Ti(III) sites. Due to this, Pt-Cu interaction, as well as the mutual potentiating action of Pt and TiO2 eases the oxidative detachment of CO poisonous intermediates from Pt (in the dark) and enhance TiO2 photogenerated electron-hole separation efficiency (under illumination).