Unique Geometrical and Electronic Properties of TM2B2 Quadruple Active Sites Supported on C2N Monolayer Toward Effective Electrochemical Urea Production

Abstract

Developing high-performance electrocatalysts for urea production using CO2 and N2 holds great potential to mitigate environmental pollution and energy crisis. In this study, 26 kinds of quadruple TM2B2 ensembles supported on porous C2N monolayer are designed as the potential electrocatalysts, with the expectation to provide sufficient space for the co-adsorption of CO2 and N2 and fulfill a synergistic effect of transition metal (TM) and boron atoms. Cr2B2@C2N is selected as the promising electrocatalyst with a record-low limiting potential of −0.37 V (vs RHE) in the neutral environment, by using a three-step screening strategy, i.e., stability of the catalyst, adsorption pattern of N2, and desorption of urea. With the help of artificial intelligence approaches, simple geometric and electronic descriptors are identified for the selectivity and activity of the electrocatalysts, which correlate strongly with the TM-B distance and the number of d electrons and electronegativity of TM atoms. The geometric descriptor narrows the scope to the early-TM-containing systems while the electronic descriptor produces the Cr-containing system. Results of this study provide a novel perspective to the electrochemical synthesis of urea that is useful to the rational design of effective electrocatalyst toward urea production.