Optimizing the electronic structure of copper and cobalt dual-sites for efficient electrosynthesis of urea

Abstract

Construction of dual catalytic sites to regulate the adsorption and activation of CO2 and NO3− is critically important for selective electrosynthesis of urea. Here, we report a CuCo alloy nanoparticles encapsulated in N-doped carbon nanotubes (CuCo@N-CNTs) catalyst for efficient and selective electrosynthesis of urea. The results demonstrated that the carbon nanotubes and the molar ratio of Cu to Co have key influence on the surface electronic structure of CuCo@N-CNTs, thus effectively regulating the adsorption and activation of CO2 and NO3− to obtain high-efficiency urea synthesis. As a result, the fabricated Cu1Co1@N-CNTs exhibited the highest urea yield of 3489.01 ± 34.35 μg h−1 mgcat−1 with a Faraday efficiency of 73.69 ± 1.83% at −0.8 V (vs. RHE). The in-situ spectroscopy and mass spectrometry measurements revealed that the first C−N coupling reaction is to generate *CONH2 species through *CO and *NH2 originated from the co-reduction of CO2 and NO3− on Cu1Co1@N-CNTs. This can be further supported by the theoretical calculations results. Furthermore, the competitive side reactions such as CO2 reduction, H2 evolution and NO3− reduction can be effectively suppressed by modulating the position of the d-band centre of CuCo alloy nanoparticles, promoting the electrosynthesis of urea.