One of the most important methods for the reduction of dinitrogen to ammonia is the Haber-Bosch process and this reaction is vital to agriculture and currently consumes ~2% of global energy. This reaction also produces a large amount of CO2 because of using of fossil fuels to run the reaction at high temperatures. Electrocatalytic reduction of N2 – the nitrogen reduction reaction (NRR) – is an environmentally friendly replacement for producing NH3. A lot of electrocatalysts such as noble and non-noble metal oxides and nitrides are being investigated for this purpose. Recently, interest in cobalt oxynitride and other Earth-abundant oxynitrides is growing for NRR. However, one important issue is still unclear, and it is the role of lattice N and lattice O in this reaction. Based on DFT calculations, both lattice N and solvated N2 can be reduced to ammonia by cathodic polarization of cobalt oxynitride films. Both lattice N and N2 reduction mechanisms involve oxide-supported Co surface sites ([Co]O in preference to N-supported sites ([Co]N). Moreover, the result demonstrates that the formation of CoN, Co-N=N-H, and other proposed reaction intermediates prefer [Co]O rather than [Co]N surface sites.

Computational study of cobalt oxynitride electrocatalyst for ammonia production

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.