Highly efficient and selective electrosynthesis of urea via co-reduction of carbon dioxide and nitrate over the TiNx catalyst

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Green and sustainable electrosynthesis of urea at ambient conditions through co-reduction of CO2 and NO3− (CR-CO2/NO3−) is regarded as a new avenue for nitrogen fertilizer production, however, the lack of novel electrocatalysts capable of selective C-N coupling hinders its wide application. Herein we reported a TiNx catalyst (TiN/TiN0.3) prepared by facile electric explosion method for electrocatalytic urea synthesis via CR-CO2/NO3−. The derived catalyst with porous nanostructure and specific active phase (TiN0.3) is more conductive for efficient C-N coupling. Consequently, a faradaic efficiency (FE) of 43.1 ± 3.1 % and a urea formation rate as high as 1488 ± 95 μg h−1 mgcat−1 were reached over the TiNx electrode, outperforming most of the reported CR-CO2/NO3− systems toward urea synthesis. In-situ attenuated total reflection Fourier transformed infrared spectroscopy and isotope-labeling experiments demonstrated the details about electrochemical coupling processes. The simulation study suggested that the TiN0.3 (100) facet facilitates the electroreduction of CO2 and NO3−, and decreases the energy barrier for generation of the key intermediates (*CO/*NH2), thus leading to the selective formation of urea. This work accomplished highly efficient electrochemical CR-CO2/NO3− toward nitrogen fertilizer production over a novel TiNx electrocatalyst for the target process.