Partially oxidized niobium carbonitride as a non-platinum catalyst for the reduction of oxygen in acidic medium

Partially oxidized NbC0.5N0.5 has been evaluated as a non-platinum catalyst for the reduction of oxygen in acidic medium. NbC0.5N0.5 powder was partially oxidized in N2 gas containing O2 of 10−4 atm at the temperature range of 700–1000 °C. Partially oxidized NbC0.5N0.5 had a definite oxygen reduction reaction (ORR) activity, while as-prepared NbC0.5N0.5 and completely oxidized Nb2O5 had a poor catalytic activity for ORR. The onset potential of the partially oxidized NbC0.5N0.5 for the ORR achieved 0.92 V vs. RHE in 0.1 M H2SO4 at 30 °C. The results of X-ray absorption spectroscopy and ionization potential measurements suggested that oxygen-vacancy defects might be responsible for the oxygen reduction capability by creating electronically favorable oxygen adsorption sites.