Separating the active sites of intermediates is a promising strategy to improve the N-modified Co₃Mo₃C catalytic activity for AOR.

Abstract

Since the facile oxidation of ammonia is one key for its utilization as a zero-carbon fuel in a direct ammonia fuel cell, developing the ammonia oxidation reaction (AOR) catalysts with cost-effective and higher activity is urgently required. However, the catalytic activity of AOR is limited by the scaling relationship of the intermediate adsorption. Based on the density functional theory, the N-modified Co₃Mo₃C with separated active sites of NH₃ dehydrogenation and N−N coupling has been designed and investigated, which is a promising strategy to circumvent the scaling relationship, achieving improved AOR catalytic performance with a lower theoretical overpotential of 0.59 V under fast reaction kinetics condition. The calculation results show that the hollow site (Co−Mo−Mo and Co−Co−Mo) and Co site in N-modified Co₃Mo₃C play essential roles in NH₃ dehydrogenation and N−N coupling, respectively. This work not only benefits for understanding the mechanism of AOR, but also provides a fundamental guidance for rational design of AOR catalysts.