Ambient Electrosynthesis of Urea with Nitrate and Carbon Dioxide over Iron-Based Dual-Sites

The development of efficient electrocatalysts to generate key *NH2 and *CO intermediates is crucial for ambient urea electrosynthesis with nitrate (NO3-) and carbon dioxide (CO2). Here we report a liquid-phase laser irradiation method to fabricate symbiotic graphitic carbon encapsulated amorphous iron and iron oxide nanoparticles on carbon nanotubes (Fe(a)@C-Fe3O4/CNTs). Fe(a)@C-Fe3O4/CNTs exhibits superior electrocatalytic activity toward urea synthesis using NO3- and CO2, affording a urea yield of 1341.3 +/- 112.6 mu g h(-1) mg(cat)(-1) and a faradic efficiency of 16.5 +/- 6.1 % at ambient conditions. Both experimental and theoretical results indicate that the formed Fe(a)@C and Fe3O4 on CNTs provide dual active sites for the adsorption and activation of NO3- and CO2, thus generating key *NH2 and *CO intermediates with lower energy barriers for urea formation. This work would be helpful for design and development of high-efficiency dual-site electrocatalysts for ambient urea synthesis.

Automated summary

In this study, a liquid-phase laser irradiation method was used to fabricate symbiotic graphitic carbon encapsulated amorphous iron and iron oxide nanoparticles on carbon nanotubes (Fe(a)@C-Fe3O4/CNTs) as efficient electrocatalysts for ambient urea synthesis. The Fe(a)@C-Fe3O4/CNTs exhibited superior electrocatalytic activity towards urea synthesis using NO3- and CO2, with high urea yield and faradic efficiency at ambient conditions. The formation of Fe(a)@C and Fe3O4 on CNTs provided dual active sites for the adsorption and activation of NO3- and CO2, facilitating urea formation with lower energy barriers.