Dataset for "Observation of Metal-Organic Interphase in Cu-based Electrochemical CO2-to-Ethanol Conversion"

Interphases play a pivotal role in various electrochemical systems, significantly influencing performance in applications such as lithium-ion batteries by governing ion transport and electrochemical stability. This paper presents the observation of a metal-organic interphase in the electrocatalytic reduction of CO2 (CO2RR) on Cu, expanding the understanding of interphase from established electrochemical systems to CO2 conversion processes. Our investigation specifically targeted the organic modification of Cu surface. While we initially anticipated monolayer adsorption of the organic modifiers, we observed the formation of metal-organic interphases exceeding 10 nm in thickness for the modifiers with high ethanol selectivity. This finding comes from a systematic investigation of 180 nitrogen/oxygen/sulfur-terminated or water-insoluble molecular modifiers utilizing an automatic electrocatalysis platform. After 1080 CO2RR experiments, we identified the functional group properties that impact selectivity for ethanol and multi-carbon (C2+) products during CO2RR. Notably, several alkyl thiolates enhance ethanol selectivity—a phenomenon previously attributed to hydrophobic surface modifications of the catalyst. However, some modifiers without a thiol-group or even hydrophilic modifiers can also promote ethanol production. We found that these modifiers consistently produce metal-organic interphases on the Cu or CuOx surface. This interphase crucially modulates Cu surface coordination, CO2RR intermediates, and interfacial water configuration, markedly altering the catalyst's electrochemical properties. The efficacy and generality of this functionalization approach was confirmed across 11 different CuOx-based catalysts, culminating in the development of two electrocatalysts that achieved ~80% faradaic efficiency for C2+ products with ethanol partial current densities up to 328 and 507 mA cm−2, respectively. This study documents interphase in CO2RR systems, underscoring its essential role in boosting electrocatalytic performance and representing a significant advancement in CO2 conversion technology.