Confining Reaction Intermediates in Oxide-Derived Hollow Cu-Zn Bimetallic Catalyst Facilitates Selective Formation of C2+ Alcohols from Electrochemical Carbon Dioxide Reduction.

Copper has long been the only element known to produce multicarbon (C2+) products from CO2 through electrochemical pathways. However, its low kinetic barrier favors ethylene formation over C2⁺ alcohols at the selectivity-determining step (SDS). Alloying Cu with secondary metals has been explored to shift selectivity toward alcohols, but these approaches often suffer from poor activity and selectivity. In this work, we probe the role of confinement of reaction intermediates in favoring C2+ alcohol selectivity and overall C2+ product in oxide-derived hollow Cu-Zn bimetallic catalysts. From finite element method (FEM) simulation, it was observed that hollow catalyst increases the retention time of the reaction intermediates that favor the C─C coupling. Confinement gives rise to a two-fold increment in the overall C2+ product. We observed that the hollow Cu-Zn catalyst gives a Faradaic efficiency (FE) of 50.13% toward C2+ alcohol and an overall FE of 81% toward C2+ product at a very high current density of 300 mA cm-2 in 1 M KHCO3. DFT calculation shows that Zn affects selectivity determining step (SDS) and favors the formation of alcohol over ethylene. Various in situ techniques, such as X-ray absorption spectroscopy, infrared spectroscopy, Raman spectroscopy, and differential electrochemical mass spectroscopy, were used to understand the active phase of the catalyst and mechanism in detail.