Catalytic activity of Zr oxynitrides prepared by reactive sputtering for oxygen reduction reaction

Abstract

Zirconium-based compounds prepared by an R.F. reactive sputtering method using Zr target under Ar+0₂+N₂ atmosphere with heating a substrate were evaluated as a non-platinum cathode for polymer electrolyte fuel cells. The effect of the substrate temperature and the gas atmosphere during the film formation on the catalytic activity for the oxygen reduction reaction (ORR) and the characteristics of the films were investigated. The catalytic activity for the ORR increased with the increasing substrate temperature. The ZrO_xN_y prepared at P_Ar=0.886 Pa, P_N2=0.41Pa, and P_O2=1.7m Pa with a substrate temperature of 800°C had a superior catalytic activity for the ORR. The onset potential for the ORR had a maximum of 0.8 V vs. RHE. Thin film XRD analysis revealed that the ZrO_xN_y with a high catalytic activity for the ORR contained the Zr₂ON₂ crystalline structure.