Metallated Graphynes\nas Efficient Single-Atom Electrocatalysts\nfor Nitric Oxide Reduction\nto Ammonia

Abstract

Direct electrochemical ammonia synthesis from nitric\noxide is regarded\nas an attractive strategy to degrade NO contaminants into valuable\nNH₃, but the scarcity of high-efficiency and durable electrocatalysts\nto facilitate such a process impedes its applications. The emerging\ntransition metal 1,3,5-triethynylbenzene frameworks (TM-TEB), combining\nthe superiorities of single-atom metal centers and graphynes, offer\nattractive possibilities in electrochemical catalysis. This work comprehensively\nstudies the TM-TEB systems (for TM from the first three d-block series)\nand explores their potential applications as electrocatalysts for\nthe NO reduction reaction (NORR) to value-added NH₃. By\ndeveloping rational strategies, the systems with TM = Cr, Pd, and\nPt are successfully screened out as the NORR-to-NH₃ electrocatalysts\nwith superiority catalytic activity. With further consideration of\nthe selectivity, Cr-TEB is identified as a promising candidate with\nhigh catalytic activity and outstanding selectivity. Interestingly,\nboth the Δ<i>G</i>_*NO and integrated crystal\norbital Hamilton population (ICOHP) of TM-NO or N–O could be\nsuitable descriptors to demonstrate the catalytic activity of the\nNORR to NH₃. This work has fundamental scientific implications\nfor understanding the TM-TEB systems and demonstrates their great\npotential as the electrocatalysts for the NORR to NH₃,\nwhich will motivate further exploration of the applications of TM-TEB\nin catalysis.