Heterostructure of ZnO Nanosheets/Zn with a Highly Enhanced Edge Surface for Efficient CO2 Electrochemical Reduction to CO

Electrochemical reduction of CO2 to valuable chemicals or fuels is critical for closing the carbon cycle and preventing further deterioration of the environment. Here, we discover that by adopting the Zn foil as the substrate, a ZnO two-dimensional sheet array is in situ synthesized on the Zn foil by a facile hydrothermal method. The obtained ZnO sheet array/Zn foil exhibited an outstanding CO2 reduction performance to CO, which showed the highest Faraday efficiency of 85% for CO at -2.0 V (vs Ag/AgCl) with a current density of 11.5 mA/cm(2) compared with the freestanding ZnO sheets and particles and excellent stability in the 0.1 M KHCO3 electrolyte. The in situ vertical ZnO sheet array exposed with abundant exposed (1 (1) over bar 00) edge facets can accelerate the electron transfer and improve the number of active sites, which leads to the enhanced reduction performance. Alongside, the density functional theory simulation indicated that the vertical-grown ZnO sheet array possesses lower Gibbs free energy for the CO2 activation, with a more exposed (1 (1) over bar 00) edge surface of ZnO.

Automated summary

The study demonstrates that in situ synthesis of ZnO on Zn foil can significantly enhance the CO2 reduction performance, leading to higher Faraday efficiency for CO and improved stability. This enhancement is attributed to the exposed edge facets of ZnO that accelerate electron transfer and increase the number of active sites.