What question did this study set out to answer?

This research aims to improve urea synthesis through the electrochemical co-reduction of CO2 and nitrite using bimetallic catalysts.

January 20, 2026Open Access

Spectroelectrochemical insight into copper cobalt catalysts for CO2 and nitrite co-electroreduction to urea

Key Points

This research aims to improve urea synthesis through the electrochemical co-reduction of CO2 and nitrite using bimetallic catalysts.
Developed co-sputtered bimetallic Cu-Co catalysts with varied ratios.
Measured urea yield rates at specific voltages and conditions.
Utilized spectroscopic techniques for in situ analysis of reaction intermediates.
Conducted density functional theory calculations for mechanistic insights.
Achieved a urea yield rate of 61 ± 6 mmol h⁻¹gcat⁻¹ at an optimal Cu:Co ratio of 1:1.
Identified *COOH + *NH2 coupling as the starting point for urea formation.
Demonstrated that proton balance is critical for efficient electron transfer during the reaction.

Abstract

Electrochemical CO2 and nitrite co-reduction provides a sustainable urea synthesis route but remains limited by low selectivity and an undecided C-N coupling mechanism. Here, we report co-sputtered bimetallic Cu-Co catalysts that facilitate urea formation via a tandem relay mechanism. The optimal Cu:Co ratio of 1:1 achieves a urea yield rate of 61 ± 6 mmol h⁻1gcat⁻1 at -1.2 V vs. RHE under neutral pH, emphasizing the importance of proton balance in sustaining proton-coupled electron transfer. In situ synchrotron-based infrared and Raman spectroscopy monitor the dynamic evolution of *CO, *NH2, and C‒N intermediates. In situ X-ray absorption spectroscopy indicates the structural stability of metallic Cu and Co active sites. Density functional theory calculations suggest that *COOH + *NH2 coupling initiates urea pathway, with *NH2CO formation as the potential-determining step. This study integrates rational catalyst design and in situ spectroelectrochemical analysis to advance understanding of electrochemical C-N coupling for urea synthesis.

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