DFT Study of N-modified CoMoC Electrocatalyst with Separated Active Sites for Enhanced Ammonia Oxidation.

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 CoMoC with separated active sites of NH 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 CoMoC play essential roles in NH 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.