Nature of C─N Coupling in Urea Electrosynthesis for Catalyst Design.

Abstract

Electrocatalytic co-reduction of CO2 and NO3 - offers a low-carbon route to urea, yet practical deployment is constrained by unsatisfactory efficiency due to the absence of a quantitative, theory-guided catalyst design principle. In this study, we propose the generalized dipole moment (GDM) of active sites as a transferable descriptor guided by charge-locking asymmetric site polarization (CLASP) mechanism, that can quantify polarization strength correlated with selectivity prediction for catalysts. Constant-potential simulations show that increasing GDM strengthens *CO2 adsorption, promotes H2O dissociation, and progressively favors C─N coupling relative to the competing protonation pathway. The slow-growth method further tracks charge evolution along the *CO─*NO coupling coordinate, confirming that polarized active sites precharge *CO and facilitate the predominant C-to-N charge-redistribution tendency during formation of critical coupling intermediates. Guided by this descriptor, a series of Ln─Cu alloy catalysts were designed to validate the predicted scaling, with La─Cu as the best candidate.