Bi2O3 microspheres combined electron-deficient B-reduced graphene oxide as functional electrocatalyst for effective synthesis urea from N2 and CO2

Abstract

Electrochemical synthesis urea, which couples N2 and CO2, is seen as a potential promising and sustainable alternative to traditional harsh industrial process. However, the significance of the rational design electrocatalyst has been enthused due to the hard activation of N≡N, the prevalence of sub-reactions, and the low current density. Herein, an electrocatalyst, Bi2O3/B-reduced graphene oxide (RGO) was prepared for synthesis urea with a Faraday efficiency (FE) of 12.8 %, urea yield of 9.2 mmol g−1h−1 and urea current density 0.47 mA cm−2 at −0.8 V, while maintaining long-term stability. The Bi2O3/B-RGO possess a unique porous structure with continuous micron pores that facilitated the rapid mass transfer, improved kinetic efficiency and enlarged electroactive sites, which together improve the urea synthesis performance. Interestingly, the Bi2O3/B-RGO electrocatalyst is not only have excellent electrochemical properties, but also favours the adsorption and activation of reactants (N2 and CO2) due to the B-RGO (Lewis acid) and the Bi2O3 (Lewis base). This work may provide new insights into the exploration of advanced catalysts for electrochemical urea synthesis and other sustainable applications.