Group 4 and S Oxide-Based Compounds as New Cathodes without Platinum Group Metals for PEFC

摘要

A partially oxidized TaC_(0.58)N_(0.42) has been investigated as a new cathode for polymer electrolyte fuel cells. The catalytic activity for oxygen reduction reaction (ORR) significantly depended on an oxidation state of the TaC_(0.58)N_(0.42). TaC_(0.58)N_(0.42) and Ta_2O_5 had a poor catalytic activity for the ORR. The onset potential on the partially oxidized TaC_(0.58)N_(0.42) for the ORR had a maximum value of 0.9 V vs. RHE in 0.1 mol dm~(-3) H_2SO_4 at 30℃. Hard X-ray PhotoElectron Spectroscopy and XRD analyses indicated that the surfaces of the partially oxidized TaC_(0.58)N_(0.42) were oxidized, although the inner parts of the partially oxidized TaC_(0.58)N_(0.42) remained tantalum carbonitride. This result indicated that an appropriate oxidation of the TaC_(0.58)N_(0.42) was essential to enhance the catalytic activity for the ORR.