CO oxidation and CO 2 reduction on carbon supported PtWO 3 catalyst

Abstract

The activity of a carbon supported PtWO 3 (PtWO 3/C) catalyst in the CO oxidation and CO 2 reduction reactions was evaluated in sulfuric acid solution at room temperature. Cyclic voltammetry combined with on-line mass spectrometry shows that the oxidation of both saturated CO adlayer and dissolved CO on PtWO 3/C material commences at rather low potentials, ca. 0.18 and 0.12 V vs. RHE, respectively. However, the low-potential process seems to involve only a minor fraction of the CO adlayer, the major part of the adsorbed CO layer being oxidised at the potentials as high as those for pure Pt catalysts—ca. 0.7 V vs. RHE. PtWO 3/C material was found to reversibly de-activate upon a prolonged exposure to the CO-saturated solution due to the inhibition of the hydrogen tungsten bronze formation. The reduction of CO 2 on PtWO 3/C leads to the formation of an adsorbate – presumably CO – on the Pt sites of the catalyst. Although the rate of the adsorbate build-up on PtWO 3/C at 0.1 V is lower than that on pure Pt/C, our results indicate that upon a prolonged exposure of the PtWO 3/C electrode to a CO 2-saturated solution a complete poisoning of the Pt sites with the adsorbate is likely to occur at room temperature.