Potential-driven dynamic strain in chemical bonds for urea electrosynthesis.

Regulating the bond lengths of electrocatalysts to manipulate their surface-attached intermediates is crucial for orienting the parallel NO3 - and CO2 reduction pathways towards the target urea product. However, in potentiostatic systems, the fixed bond lengths cannot selectively control the competition among multiple thermodynamic processes. Herein, we successfully balanced the activities of NO3 - and CO2 reduction in urea electrosynthesis by constructing a potential-driven dynamic system, in which the Cu-O bond lengths in the Cu5-PPF electrocatalyst were precisely controlled between 2.12/2.24 Å and 2.37/2.34 Å. The dynamic elastic strain of Cu-O bond lengths optimized the N- and C-pathways separately, achieving the highest urea-selective performance at equilibrium. In the dynamic system, the FEurea was up to 61.6%. In situ spectroscopy and theoretical analyses revealed that the shorter Cu-O bond lengths favored the N-pathway, promoting the generation of key *NO intermediates, while the elongated Cu-O bond lengths enhanced the adsorption of CO2 and the formation of *COOH in the C-pathway. Moreover, controlled experiments revealed that the dynamic system did not enhance the FEurea of Cu3-TPF and Cu3-clusters due to their structural rigidity, further highlighting the importance of dynamic bond strain in optimizing catalytic performance.