Reduction of nitrate on tin-modified palladium-platinum electrodes

The Sn-modified PdPt (Sn/PdPt) electrodes, prepared on Au film substrates by sputtering the PdPt alloy followed by Sn-adsorption, were characterized by cyclic voltammetry and X-ray photoelectron spectroscopy and examined for the reduction of nitrate. The unmodified PdPt (Pd/Pt = 31/69) electrodes did not show any catalytic activity for the nitrate reduction. Tin-modification of the electrodes significantly increased the reduction activity, and the maximum activity was obtained at the Sn surface coverage (θSn) of 0.8. The main reduction product was N2 (44%). Based on the comparison of the observed electrocatalytic activity and product distribution on the Sn/PdPt electrodes and that expected for a physical mixture of Sn/Pt and Sn/Pd, it became clear that there exist synergetic effects between the Pd and Pt on both the activity and N2 production. Further analysis of the product distribution based on the number of bond formations and cleavage clarified that the N2 production capability was enhanced as a result of the enhanced NO bond cleavage, NN bond formation, and the reduced NH bond formation. [Display omitted] •Sn/PdPt electrodes were prepared by the sputtering PdPt alloy and Sn-adsorption.•Sn/PdPt electrodes were examined for the reduction of nitrate.•The maximum activity of the nitrate reduction was obtained at the Sn coverage of 0.8.•The main reduction product was N2 (44%).•The synergetic effects of Pd and Pt on the activity and N2 production were observed.