Simultaneous electrocatalytic reduction of dinitrogen and carbon dioxide on conducting polymer electrodes

Electrocatalytic C–N Coupling for Urea Synthesis

“…Reproduced with permission. [ 15 ] Copyright 2016, Elsevier Ltd. d) Electrocatalytic coupling of carbon dioxide and nitrogen to synthesize urea under ambient conditions. Reproduced with permission.…”

“…[ 14 ] Utilizing aqueous solution instead of hydrogen as the proton source would exploit the advantages of green urea synthesis and it was realized in a pressurized apparatus, as shown in Figure 3c. [ 15 ] In the mixed atmosphere of carbon dioxide (30 bar) and nitrogen (30 bar), the urea formation rate reaches the highest value of 31.8 μg h −1 cm −2 over the polypyrrole catalyst at −0.325 V (vs. normal hydrogen electrode (NHE)). Shifting the high‐pressure working condition to an ambient one would minimize the requirements for synthesis equipment as much as possible.…”

“…[12,18] The electrochemical urea synthesis at elevated pressure was achieved by Kayan and collaborators. [15] They proposed that urea production arises from the chemical reaction between carbon dioxide and ammonia from nitrogen reduction, and then the generated ammonium carbamate is converted to urea with one water molecule release. However, the driven force and the inherent mechanism for the generation of carbamate and urea have not been studied yet.…”

“…Catalyst [ref. ] Carbon source Nitrogen source Electrolyte Applied potential Urea yield rate Faradic efficiency Polypyrrole film [15] 30 bar CO 2 30 bar N 2 0.1 M Li 2 SO 4 þ 0.03 M H þ À0.325 V versus NHE 31.8 μg h À1 cm À2 6.9%…”

Electrochemical C–N coupling with perovskite hybrids toward efficient urea synthesis

“…33,34 The industrial urea synthesis proceeds by two consecutive processes, including N 2 + H 2 / NH 3 followed by NH 3 + CO 2 / CO(NH 2 ) 2 , which operate under harsh reaction conditions (350-550 C, 150-350 bar and 150-200 C, 150-250 bar, respectively). 35 Compared with the complex industrial synthetic process, simultaneous electrocatalytic xation of N 2 and CO 2 driven by a renewable energy source under ambient conditions provides a clean route for urea production. 9 The main issues in electrochemical synthesis of urea lie in three aspects: (1) extraordinarily weak chemical adsorption of inert CO 2 /N 2 on the catalysts surface; 29,30,36,37 (2) the dissociation of the highly stable C]O bond and N^N bond requires high overpotential; 13,15 (3) the parallel reaction of CO 2 /N 2 reduction suppresses the efficiency of C-N coupling and strongly competes with the desired urea formation reaction, further resulting in a large distribution of complex products.…”