An oxygen-coordinated cobalt single-atom electrocatalyst boosting urea and urea peroxide production

Abstract

Urea and urea peroxide play important roles in agricultural and industrial production. The development of mild and efficient synthetic methods to achieve these two chemicals has attracted great attention, but a huge challenge. Here, we report an oxygen-coordinated cobalt single-atoms catalyst (Co–O–C) for ambient electrosynthesis of urea and hydrogen peroxide, respectively, then achieving urea peroxide. As a result, Co–O–C exhibits superior electrocatalytic activity toward urea synthesis with CO₂ and NO₃⁻, affording a remarkable urea yield rate of 2704.2 ± 183.9 μg h⁻¹ mg_cat.⁻¹ and the corresponding faradaic efficiency of 31.4 ± 2.1% at −1.5 V (vs. RHE). In a flow cell, the Co–O–C delivers an apparently enhanced R_urea value of 4648.2 ± 401.2 μg h⁻¹ mg_cat.⁻¹ and a FE value of 53.2 ± 4.6% at −1.4 V (vs. RHE). Noticeably, Co–O–C also demonstrates superior electrocatalytic activity of two-electron oxygen reduction reaction (2e⁻ ORR) with an H₂O₂ yield rate of 538.8 ± 2.7 mmol h⁻¹ g_cat.⁻¹ at 0 V (vs. RHE). Utilizing the synthesized urea and H₂O₂ as reactants, urea peroxide was successfully produced. The X-ray absorption fine structure spectrum reveals the dynamic surface reconstruction of Co–O–C under ambient electrocatalysis. The theoretical calculations uncover that the strong interactions between adjacent Co–(O–C₂)₄ moieties facilitate the C–N coupling for urea and the formation of *OOH intermediates for H₂O₂.