Spectroelectrochemical insight into copper cobalt catalysts for CO2 and nitrite co-electroreduction to urea
Putri Ramadhany, Thành Trần-Phú, Jodie A. Yuwono, Rosalie K. Hocking, Zhipeng Ma, Xuan Minh Chau Ta, Priyank V. Kumar, Denny Gunawan, Bernt Johannessen, Antonio Tricoli, Alexandr N. Simonov, Rose Amal, Rahman Daiyan
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. Electrochemical conversion of CO2 and nitrite offers a green route to produce urea. Here, the authors report co-sputtered copper cobalt catalysts enable efficient C–N coupling through a tandem mechanism, yielding 61 mmol h⁻1gcat⁻1 urea at –1.2 V vs. RHE.