Enhanced photocatalytic synthesis of urea from co-reduction of N2 and CO2 on Z-schematic SrTiO3-FeS-CoWO4 heterostructure.

Abstract

The photocatalytic co-reduction of CO2 and N2 is a sustainable method for urea synthesis under mild conditions. However, high-yield synthesis of urea is a challenge due to the sluggish kinetics of the C-N coupling reaction. Herein, we have successfully engineered a Z-scheme photocatalyst, SrTiO3-FeS-CoWO4, for boosting photocatalytic urea synthesis via enhancing the initial CO2 and N2 adsorption step and reducing the energy barrier for the C-N coupling reaction. A high urea yield of 8054.2 μg·gcat-1·h-1 was achieved on SrTiO3-FeS-CoWO4, which was significantly higher than the state-of-the-art. The SrTiO3-FeS-CoWO4 Z-scheme photocatalyst, with accelerated charge transfer by FeS, not only had dual active sites for the chemical adsorption and activation of CO2 and N2, but also retained the high conduction band (-1.50 eV) and accelerated supply of electrons and protons, which are responsible for its good photoreduction activity and significantly reduced energy barrier for the rate-determining step of C-N coupling reaction.