Controlling C-C coupling in electrocatalytic reduction of CO2 over Cu1-xZnx/C.

ABSTRACT

From the perspective of sustainable environment and economic value, the electroreduction of CO2 to higher order multicarbon products is more coveted than that of C1 products, owing to their higher energy densities and a wider applicability. However, the reduction process remains extremely challenging due to the bottleneck of C-C coupling over the catalyst surfaces, and therefore designing a suitable catalyst for efficient and selective electrocatalytic reduction of CO2 is a need of the hour. With the target of producing C3+ products with higher selectivity, in this study we explored the nano-alloys of Cu1-xZnx as electrocatalysts for CO2 reduction. The nano-alloy Cu1-xZnx synthesized from the corresponding bimetallic metal organic framework materials demonstrated a gradual enhancement in the selectivity of acetone upon CO2 electroreduction with higher doping of Zn. The Cu1-xZnx alloy opened up a wide possibility of fine-tuning the electronic structure by shifting the position of the d-band centre and modulating the interaction with intermediate CO and thus enhanced the selectivity of desirable products, which might not have been accessible otherwise. The postulated molecular mechanism of CO2 electroreduction involving the desorption of the poorly adsorbed intermediate CO due to the presence of Zn and spilling over of free CO to Cu sites in the nano-alloy Cu1-xZnx for further C-C coupling to yield acetone was corroborated by the first principles studies.