Electrochemical Nitrate Reduction at Sn-Modified Single Crystalline Metal Electrodes

Abstract

Sn-modified Pt, Pd and PtPd alloy electrodes have been known as the most active electrode for the electrochemical reduction of nitrate, which becomes abandant in ground water and industrial drain water. However, these electrodes were usually polycrystalline and the research at well-defined electrode surfaces were required to understand the reaction mechanism and the nature of reaction sites. In the present study, we prepared Sn-modified Pt(111) and Pd(111) electrodes to investigate the nitrate reduction in acidic solution. Pd-doped Pt(111) electrodes are also prepared. The coverage dependences of Sn at single crystalline electrodes on the activity toward nitrate reduction have been estimated by CV in detail. For Pt(111) and Pd(111), the oxidation induced alloying between Sn and the substrate, which was confirmed by XPS measurements, caused enhancement in the electrochemical activity toward nitrate reduction.