Au Nanocrystals@Defective Amorphous MnO2 Nanosheets Core/Shell Nanostructure with Effective CO2 Adsorption and Activation toward CO2 Electroreduction to CO

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(@-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 similar to 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 CO2 ER to CO. This work integrates conductivity promotion and defect engineering by noble-metal@defective amorphous oxide core/shell nanostructure toward improved CO2ER.

Automated summary

Au nanocrystals@defective amorphous MnO2 nanosheets core/shell nanostructure was developed for efficient CO2 electroreduction to CO. The optimized structure with 60 nm nanosheets shell size achieved the highest faradic efficiency for CO production and exhibited excellent stability.