ZIF-8 derived porous ZnO with grain boundaries for efficient CO2 electroreduction

Electrocatalytic CO2 reduction reaction has been considered as a promising route to realize carbon cyclic utilization and renewable energy storage. Recently, Zn-based catalysts have attracted much attention due to their earth-abundant reserve and low cost, which can meet the demand for commercial applications at a large scale. Herein, ZnO catalyst (ZIF-8-D-ZnO) was synthesized by pyrolysis of ZIF-8 precursor for electrocatalytic reduction of CO2. The ZIF-8-D-ZnO catalyst exhibits an excellent catalytic activity for CO production than rod-like ZnO and Zn foil catalysts, with faradaic efficiency of 86.7 % and geometric current density of 16.1 mA cm−2 at −1.2 V (vs. RHE). Moreover, the overpotential over ZIF-8-D-ZnO is much lower than that of analogous catalysts. The results suggest that the grain boundaries within the porous structure facilitate CO2 electroreduction over ZIF-8-D-ZnO due to the introduction of new catalytically active sites. This work provides experimental evidence for the design of efficient Zn-based materials for CO2 electrocatalytic reduction. ZIF-8-D-ZnO catalyst with porous structure and grain boundaries exhibits much higher CO faradaic efficiency and current density than ZnO-R and Zn foil catalysts.