C2 product selectivity by 2D-nanosheet of layered Zn-doped Cu2(OH)3(NO3)- a pre-catalyst for electrochemical CO2 reduction

Abstract

The natural carbon cycle cannot mitigate and recycle the excess CO2 in the atmosphere, leading to a continuous rise in the global temperature. Electrochemical conversion of CO2 is one of the useful methods to utilise this anthropogenic CO2 and convert it into value-added chemicals. However, this process suffers the challenges of product selectivity and good Faradaic efficiency. In our current work, we report the role of Zn-doping in the 2D-Nanosheet of Cu2(OH)3(NO3)- a pre-catalyst that undergoes the in situ transformation into metallic state along with surface reconstruction. Our studies show, in the aqueous medium, the optimum amount of Zn plays a crucial role in the production of ethanol with the Faradaic efficiency of ∼45.2% though C-C coupling. Temperature-programmed desorption studies conclude that Zn increases the product selectivity for CO adsorption on Cu2(OH)3(NO3) nanosheets, further facilitating the C-C coupling at higher negative potential. The detailed XPS studies also reveal that the in-situ conversion of Cu2+ to Cu0 and Cu+ at negative potential contributes to the production of C2 products. The post-catalytic microstructural and spectroscopic studies converge to this point that cumulative effect of oxidation state, surface reconstruction, as well as the presence of Zn modulates overall Faradaic efficiency for ethanol formation.