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 FE_urea 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 FE_urea of Cu₃-TPF and Cu₃-clusters due to their structural rigidity, further highlighting the importance of dynamic bond strain in optimizing catalytic performance.