Electrocatalytic Synthesis of Urea

Many industrial chemical processes involve a high-energy demand (often still derived from fossil fuels). Urea is an important chemical for the agricultural industry, which accounts for 70% of the global nitrogen-containing fertilizer usage. Currently, urea is produced by the reaction of liquid NH 3 and CO 2 [1] in a process known as the Haber-Meiser process. Despite its importance, this process suffers from high energy demand and CO 2 emissions, mainly due to the NH 3 synthesis step (Haber- Bosch process), which relies on fossil fuel resources. Making urea with electrochemical methods has recently gained interest from the scientific community as this approach provides a way to reduce the high CO 2 emissions currently associated with urea production. Among the various nitrogen sources explored for urea electrosynthesis, nitrate (NO3-) is attractive because of its high solubility in water, low dissociation energy and potential to mitigate NO 3 − contaminations in water. Even though the mechanism of urea synthesis via CO 2 and NO 3 - coupling is still controversial and not broadly studied, most reports implicate CO* and NH 2 * surface intermediates in urea synthesis. [2] Cu is an attractive electrocatalyst as it can reduce CO 2 to CO and further products and it is also an active catalyst for the reduction of nitrate to ammonia Previous reports on Cu and Cu-based materials showed that urea can be obtained from NO 2 - . [3,4] Early research by Shibata et al. with various catalysts demonstrated that the highest faradaic efficiency towards urea from NO 3 - was achieved with a Zn catalyst. [5] In this presentation, I will show our latest results on the development of Cu bimetallic catalysts ( CuRh) for urea electrosysnthesis from CO 2 and NO 3 -[6,7] . References: [1] P. N. Cheremisinoff, Waste Minimization Cost Reduct. Process Ind. 1995 , 222–284. [2] X. Liu, Y. Jiao, Y. Zheng, M. Jaroniec, S. Z. Qiao, Nat. Commun. 2022 , 13 , 1–9. [3] S. Liu, S. Yin, Z. Wang, Y. Xu, X. Li, L. Wang, H. Wang, Cell Reports Phys. Sci. 2022 , 3 , 100869. [4] N. Cao, Y. Quan, A. Guan, C. Yang, Y. Ji, L. Zhang, G. Zheng, J. Colloid Interface Sci. 2020 , 577 , 109–114. [5] M. Shibata, K. Yoshida, N. Furuya, J. Electrochem. Soc. 1998 , 145 , 595–600. [6] D. Anastasiadou, B. Ligt, Y. He, R van de Poll, J. Simons, M C Figueiredo. . Communications in Chemistry, 6, 199, 2023 [7] D. Anastasiadou, B. Ligt, , M C Figueiredo, in preparation.