Au Nanocrystals@Defective Amorphous MnO<sub>2</sub> Nanosheets Core/Shell Nanostructure with Effective CO<sub>2</sub> Adsorption and Activation toward CO<sub>2</sub> Electroreduction to CO
Junliang Zhang, Weipei Sun, Lianchun Ding, Zhengcui Wu, Feng Gao
Abstract
CO2 electroreduction (CO2ER) is a promising avenue to convert aerial CO2 into carbonaceous fuels or value-added chemicals. In this work, we constructed Au nanocrystals@defective amorphous MnO2 nanosheets core/shell nanostructure (Au NCs@a-MnO2 NSs) with tunable lateral size of nanosheets shell for efficient CO2ER to CO. The good gas-permeable behavior in the special nanocrystals/defective nanosheets core/shell nanostructure expanded the adsorption capacity of CO2 molecules. Au NCs core in Au NCs@a-MnO2 NSs brought about high electrical conductivity and boosted electron transport from the catalyst to adsorbed CO2 molecules, while a-MnO2 NSs shell with large numbers of oxygen defects favored the activation of CO2 molecules for the subsequent reduction reaction. The optimal Au NCs@a-MnO2 NSs with ∼60 nm lateral size of nanosheets shell output the utmost CO faradic efficiency (FECO) of 90.5% at −0.7 V and remained with a high FECO > 80% from −0.6 to −0.8 V. Meanwhile, Au NCs@a-MnO2-60 NSs displayed partial current densities of 3.6 mA cm–2 at −0.7 V and 14.3 mA cm–2 at −1.0 V for CO. It also exhibited outstanding stability with negligibly decreased current densities after 12 h electrocatalysis at −0.5, −0.7, and −0.9 V. The synergy between Au NCs core and a-MnO2 NSs shell is contributed to its prominent activity, selectivity, and stability for CO2ER to CO. This work integrates conductivity promotion and defect engineering by noble-metal@defective amorphous oxide core/shell nanostructure toward improved CO2ER.