Dynamic Control of Asymmetric Charge Distribution for Electrocatalytic Urea Synthesis

Abstract

Constructing dual catalytic sites with charge density differences is an efficient way to promote urea electrosynthesis from parallel ${\mathrm{NO}}_3^{-}$ and CO₂ reduction yet still challenging in static system. Herein, a dynamic system is constructed by precisely controlling the asymmetric charge density distribution in an Au-doped coplanar Cu₇ clusters-based 3D framework catalyst (Au@cpCu₇CF). In Au@cpCu₇CF, the redistributed charge between Au and Cu atoms changed periodically with the application of pulse potentials switching between -0.2 and -0.6 V and greatly facilitated the electrosynthesis of urea. Compared with the static condition of pristine cpCu₇CF (FE_urea = 5.10%), the FE_urea of Au@cpCu₇CF under pulsed potentials is up to 55.53%. Theoretical calculations demonstrated that the high potential of -0.6 V improved the adsorption of ^*HNO₂ and ^*NH₂ on Au atoms and inhibited the reaction pathways of by-products. While at the low potential of -0.2 V, the charge distribution between Au and Cu atomic sites facilitated the thermodynamic C-N coupling step. This work demonstrated the important role of asymmetric charge distribution under dynamic regulation for urea electrosynthesis, providing a new inspiration for precise control of electrocatalysis.

Keywords: asymmetric charge density distribution; dynamic catalytic system; electrosynthesis of urea; precisely control.