Efficient electrocatalysts refined from metal-dimer-anchored PC6 monolayers for NO reduction to ammonia

An electrochemical nitric oxide (NO) reduction reaction (NORR) can not only eliminate the harmful pollutant but also offer a green approach for ammonia synthesis under mild conditions. However, the activities and Faradaic efficiencies of present electrocatalysts are still not suitable for commercial applications and the mechanism has been rarely studied in detail. Here, by means of first-principles calculations and microkinetic modeling, the potentials of a series of metal-dimer anchored on the PC6 monolayer (M-2/PC6 BAC) as efficient NORR electrocatalysts were examined. Thirteen possible pathways are taken into consideration for the NORR process and a comprehensive reaction network is first constructed. Consequently, the Cr-2/PC6, Mn-2/PC6, Fe-2/PC6 and Re-2/PC6 BACs are screened out as promising candidates for NORR catalysis. Particularly, the Fe-2/PC(6)BAC exhibits the best performance among the studied BACs and its NORR rate constant (2.73 x 10(7) s(-1)) at 298.15 K is several orders of magnitude larger than those of the other BACs. It can be known from the electronic calculations that the nature of the interaction between NO and the metal-dimer is ascribed to the donation-backdonation mechanism. This work not only provides eligible BACs for NH3 synthesis but also offers an atomic understanding on the NORR process. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Through first-principles calculations and microkinetic modeling, the potential of a series of metal-dimer anchored on the PC6 monolayer as efficient NORR electrocatalysts was examined. Four promising candidates for NORR catalysis, Cr-2/PC6, Mn-2/PC6, Fe-2/PC6, and Re-2/PC6 BACs, were screened out. Among them, Fe-2/PC(6)BAC showed the best performance with a significantly higher NORR rate constant compared to other BACs. This work not only provides eligible BACs for NH3 synthesis but also offers an atomic understanding of the NORR process.