Carbon nanotubes with fluorine-rich surface as metal-free electrocatalyst for effective synthesis of urea from nitrate and CO2

In this work, carbon nanotubes with fluorine-rich surface are firstly developed as advanced metal-free catalysts for the electrocatalytic synthesis of urea via co-activation of CO2 and NO3 - under ambient conditions. A high yield rate of 6.36 mmol h-1 gcat.-1 with a corresponding Faradaic efficiency of 18.0% was achieved for the urea formation at - 0.65 V vs. reversible hydrogen electrode. Density functional theory calculations indicate the formation of *CO and *NH2 intermediates is favorable on F-doped C active sites ("C-F2" moieties), facilitating the CN coupling reaction to form urea.