Zirconium Oxide-Based Compound as New Cathode Without Platinum Group Metals for PEFC

Partially oxidized zirconium carbonitride (Zr-CNO) powders were evaluated as a nonprecious metal cathode for polymer electrolyte fuel cells (PEFCs). Zr-CNO powders were prepared from zirconium carbonitrides (ZrC0.5N0.5) with heat-treatment under N-2 containing 2% H-2 and 0.25% O-2 gas at 1000-1400 degrees C. Voltammetry was performed to evaluate the catalytic activity for oxygen reduction reaction (ORR) under nitrogen and oxygen in 0.1 mol dm(-3) H2SO4 at 30 degrees C. Although the onset potential of the ORR for untreated ZrC0.5N0.5 was 0.55 V vs a reversible hydrogen electrode (RHE), the onset potential of the appropriate oxidized Zr-CNO reached 0.97 V vs RHE. X-ray diffraction and X-ray photoelectron spectroscopy data suggested that the surface of Zr-CNO was oxidized to ZrO2, and ZrC0.5N0.5 remained in the inner part of the Zr-CNO particles. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3382960] All rights reserved.