Tip-Induced Self-Enhanced Concentration Gradients Catalyst for Sustainable Electrocatalytic Urea Synthesis.

Abstract

Electrocatalytic C─N coupling via the co-reduction of CO₂ and NO₃ ^- represents a promising route for sustainable urea synthesis under ambient conditions, simultaneously addressing critical challenges in energy sustainability and environmental remediation. However, its practical implementation is hindered by sluggish C─N coupling kinetics and the competing hydrogen evolution reaction (HER), which severely restricts energy conversion efficiency. Herein, we propose a tip-induced local electric field strategy that generates a self-enhanced concentration gradient to promote electrocatalytic C─N coupling. By constructing densely aligned Co₃O₄ nanoneedles on carbon cloth, an outstanding electrocatalytic performance was achieved, requiring only an ultra-low potential of -0.60 V versus reversible hydrogen electrode (RHE) while delivering a high urea yield rate of 49.63 umol h^-1 cm^-2 and a Faradic efficiency of 21.37%. Finite element simulations reveal that the nanoscale high-curvature tip generates an intensified local electric field, enriching potassium ions (K⁺) at the electrode-electrolyte interface to stabilize key intermediates and direct the reaction pathway toward C─N coupling. Moreover, a series of operando spectroscopic characterizations provide direct evidence for enhanced C─N coupling process under an intensified local electric field. This work offers a generalizable strategy for energy-efficient C─N coupling, paving the way for sustainable utilization of nitrogen and carbon resources.