Coupling N 2 and CO 2 in H 2 O to synthesize urea under ambient conditions

The use of nitrogen fertilizers has been estimated to have supported 27% of the world's population over the past century. Urea (CO(NH ) ) is conventionally synthesized through two consecutive industrial processes, N + H → NH followed by NH + CO → urea. Both reactions operate under harsh conditions and consume more than 2% of the world's energy. Urea synthesis consumes approximately 80% of the NH produced globally. Here we directly coupled N and CO in H O to produce urea under ambient conditions. The process was carried out using an electrocatalyst consisting of PdCu alloy nanoparticles on TiO nanosheets. This coupling reaction occurs through the formation of C-N bonds via the thermodynamically spontaneous reaction between *N=N* and CO. Products were identified and quantified using isotope labelling and the mechanism investigated using isotope-labelled operando synchrotron-radiation Fourier transform infrared spectroscopy. A high rate of urea formation of 3.36 mmol g h and corresponding Faradic efficiency of 8.92% were measured at -0.4 V versus reversible hydrogen electrode.