Carbon corrosion characteristics of CNx nanostructures in acidic media and implications for ORR performance

Abstract

Accelerated electrochemical corrosion of nitrogen-containing carbon (CN x ) oxygen reduction catalysts was performed by a chronoamperometric hold at 1.2 V versus NHE in acidic electrolyte using a rotating disk electrode system. Cyclic voltammograms were used to measure the electrochemically active quinone/hydroquinone redox reaction couple indicating the degree of carbon corrosion. Half-cell testing of CN x oxygen reduction catalyst materials showed superior carbon corrosion resistance compared to Vulcan carbon, the most ubiquitous cathode catalyst support. When oxygen reduction activity was measured before and after carbon corrosion, carbon corrosion resilience trended with the oxygen reduction activity. CN x catalysts subjected to carbon corrosion testing did not show a change in the onset of oxygen reduction reaction (ORR) activity potentials with only a slight reduction in current density, but showed improved ORR selectivity to the complete reduction of dioxygen to water.