The Last Frontiers and Challenges in Urea Electrochemical Production Using Carbon Dioxide and Nitrate.

To reach complete decarbonization by 2050, much effort must be devoted to the electrification of hard-to-abate sectors and the substitution of fossil fuels with renewable sources. Currently, one of the most polluting sectors is the ammonia production through the Haber-Bosch process which is energy-intensive. Moreover, the hydrogen needs to produce ammonia derived from steam reforming of methane gas and the water shift reaction, in turn consuming fossil fuels and emitting more than 2% of the CO2 globally. Ammonia is the building block to produce urea which is the most used nitrogen-containing fertilizer. In the past few years, urea electrosynthesis starting from CO2 and nitrate has captured significantly the interest of the scientific community as it could become the cornerstone to achieve an intense and resilient urea production to reduce emissions and avoid usage of fossil fuels. Here, we discuss the status of the latest achievements in this field, focusing on the reaction mechanisms, different types of electrocatalysts and catalysis pursued, and the detection of urea and their intermediates using a plethora of diverse instruments and methods. This review points out the most critical aspects for research and highlights the potential routes for overcoming the main issues to be solved.