Theoretical screening of single-atom electrocatalysts of MXene-supported 3d-metals for efficient nitrogen reduction

Single-atom catalysts (SACs) with metal atoms embedded in MXenes are potentially low-cost, highly efficient, and environment-friendly electrocatalysts for ammonia production due to their high sta-bility, unique electronic structure, and the highest atom utilization. Here, density functional theory calculations are carried out to systematically investigate the geometries, stability, electronic proper-ties of SACs with the 3d-transition metal M (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) atoms embedded in the Ti defect sites of Ti2CO2 (denoted as M1@Ti2CO2). A highly stable V1@Ti2CO2 catalyst has been found to show excellent catalytic performance for N2 reduction reaction to produce NH3 after screening the 3d transition metals. The results show that V1@Ti2CO2 can not only strongly adsorb N2, but also exhibits an excellent Nitrogen reduction reaction (NRR) catalytic activity with a limiting potential of only -0.20 V and a high ability to suppress the competing hydrogen evolution reaction. The excellent NRR catalytic activity of V1@Ti2CO2 is attributed to the strong covalent metal-support interaction that leads to superb N2 adsorption ability of V atom. Furthermore, the embedded V sin-gle atoms facilitate electron transfer, thus improving the catalytic performance for NRR. These re-sults demonstrate that V1@Ti2CO2 is a potentially promising 2D material for building robust elec-trocatalyst for NRR.(c) 2023, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.