Bimetallic Copper–Indium Co-Doped Titanium Dioxide Towards Electrosynthesis of Urea from Carbon Dioxide and Nitrate

Electrocatalytic urea synthesis offers great potential for sustainable strategies through CO2 and NO3− reduction reactions. However, the development of high-performance catalysts is often hampered by the complexity of synthetic methodologies and the unresolved nature of C-N coupling pathways. In this study, we present a copper–indium co-doped titanium dioxide (CuIn-TiO2) catalyst that exhibits remarkable efficacy in enhancing the synergistic reduction of CO2 and NO3− to produce urea. The bimetallic CuIn site functions as the primary active site for the C-N coupling reaction, achieving a urea yield rate of 411.8 μg h−1 mgcat−1 with a Faradaic efficiency of 6.7% at −0.8 V versus reversible hydrogen electrode (vs. RHE). A body of experimental and theoretical research has demonstrated that the nanoscale particles enhance the density of active sites and improve the feasibility of reactions on the surface of TiO2. The co-doping of Cu and In has been shown to significantly enhance electronic conductivity, increase the adsorption affinity for *CO2 and *NO3−, and promote the C-N coupling process. The CuIn-TiO2 catalyst has been demonstrated to effectively promote the reduction of NO3− and CO2, as well as accelerate the C-N coupling reaction. This effect is a result of a synergistic interaction among the catalyst’s components.