Sn Stability of Sn-Modified Pt Electrode for Reduction of Nitrate

This work investigated the stability of a Sn-modified Pt electrode for the reduction of nitrate using two type electrodes prepared by adsorption or electrodeposition of Sn onto Pt. In order to find the causes for the instability of the electrode, the effects of the condition of the solutions in which the electrode was used and the potential applied to the electrode on the electrochemical and metallurgical behaviors of the Sn on the Pt electrode were investigated. The Sn of the Sn-modified Pt electrode existed as a Sn hydroxide form, which brought about an easy loss of the electroactivity of the electrode in solution. During the reduction of nitrate, the electroactivity of the electrode was affected by the potential applied to the electrode. When a more negative potential than the redox potential between and Sn was applied, the Sn hydroxide was converted to Sn metal that was diffused into Pt, which led to a loss of electroactivity of the electrode as well. The solid diffusion of Sn increased linearly with the applied potential. The Sn-electrodeposited Pt electrode was more favorable for maintaining the integrity of the electrode during the electrolysis than the Sn-adsorbed Pt electrode.