Oxygen Reduction Reaction on Glycin Modified Pt(111) Electrode

Abstract

Oxygen reduction reaction (ORR) on glycin (NH2CH2COOH) modified Pt(111) electrode has been investigated using hanging meniscus rotating disk electrode system (HMRD) in 0.05 mol•L-1 H2SO4 and 0.1 mol•L-1 HClO4 solutions, respectively. Cyclic voltammograms of the glycin modified Pt (111) electrode measured in 0.05 mol•L-1 H2SO4 solution similar to that of CN- modified Pt(111) electrodes, demonstrating that sulfate adsorption is strongly inhibited at the glycin modified Pt(111). From the polarization curve of ORR recorded in 0.05 mol•L-1 H2SO4 solution, it is found that the ORR activity at the glycin modified Pt (111) is greatly enhanced with the half wave potential (E1/2) of ORR being shifted ca. 0.1 V positively, which is close to the activity of ORR at the unmodified Pt(111) in 0.1 mol•L-1 HClO4 solution. The improved ORR activity is explained by geometric effect due to the formation of well organized CN- adlayer at Pt(111) from the oxidative decomposition of glycin, which effectively inhibits the adsorption of sulfate anions.