Scaling relations for ammonia oxidation

The ammonia oxidation reaction (AOR) is a reaction of great interest for its potential to upcycle ammonia waste, creating fertilizer salts beneficial for the agricultural industry. Currently, AOR catalysts typically suffer either from high onset potentials or catalyst poisoning, and better catalyst materials must be found in order for AOR to be viable for large-scale fertilizer production. Experimentally, it is difficult to study the interactions of adsorbates on catalyst surfaces on an atomic level, whereas computational studies provide us with a means to study catalysts on this scale. In this study, we use density functional theory (DFT) calculations to develop linear scaling relations for ammonia oxidation using a set of ten reference metals. The scaling relations were used in a microkinetic model to predict the most active transition metal electrocatalysts for the AOR. • Established ammonia oxidation reaction linear scaling relations for the first time. • Demonstrated trends between adsorbate geometries and their Bader charges. • Observed hydrogen bonding between ammonia oxidation intermediates and transition metal surfaces. • Developed a microkinetic model with density functional theory-calculated reaction energies and approximated barriers to predict that Os, Co, and Rh should be the best catalysts for the AOR nitrate pathway.