Structure Dependent Product Selectivity for CO 2 Electroreduction on ZnO Derived Catalysts

Electrochemical conversion of CO2 is an attractive alternative to releasing it to the atmosphere. Catalysts derived from electroreduction of metal oxides are often more active than when starting with metallic phase catalyst. The origin of this effect is not yet clear. Using ZnO nanorods, we show that the initial structure of the oxide as well as the electrolyte medium have a profound impact on the structure of the catalytic active Zn phase, and thereby the selectivity of the catalysts. ZnO nanorods with various aspect ratios were electrochemically reduced in different electrolytes leading to metallic Zn with different structures; a sponge‐like structure, nanorods and nanoplates. The sponge‐like Zn produced syngas with H2 : CO=2, and some formate, the nanorods produced only syngas with H2 : CO=1, while Zn nanoplates exhibited 85 % selectivity towards CO. These results open a pathway to design new electrocatalysts with optimized properties by modifying the structure of the starting material and the electroreduction medium.
The structure to evolve: Electron micrographs illustrates the evolution of Zn structure from the electroreduction of ZnO nanorods, and the effects on the product selectivity in the CO2 electroreduction. This work shows that the structure/morphology, and hence product selectivity of oxide‐derived Zn catalysts in CO2 electroreduction, can be tuned by changing the structure/aspect ratio of the staring ZnO nanorods and the reduction condition.