A comprehensive comparison of oxygen and nitrogen functionalities in carbon and their implications for the oxygen reduction reaction

Abstract

Carbon materials have widespread use in catalysis mainly due to their abundance, high conductivity, large surface area, and facile functionalization through heteroatom-doping. However, both, the stability against corrosion and the catalytic performance caused by the exposure to high potentials present in relevant electrocatalytic reactions such as the oxygen reduction reaction (ORR) is recurrently underestimated. We demonstrate that importance of oxygen and nitrogen binding motives to tailor the oxygen reduction activity, selectivity and stability against corrosion. Spectroscopic results revealed that the exposure to high oxidative potentials causes i) oxidation of N-groups and decrease in N content; and ii) enrichment of CO (hydroxyl and ethers), CO (quinones), and COOH functional groups and, together, dramatically impact the ORR activity and selectivity. We present guidelines how the activity, selectivity and stability can be precisely tuned. The developed guidelines highlight the potential of tailoring the oxygen and nitrogen containing functional groups on carbon catalysts for future catalytic applications.