Weak CO binding sites induced by Cu–Ag interfaces promote CO electroreduction to multi-carbon liquid products

Abstract

Electrochemical reduction of carbon monoxide to high-value multi-carbon (C ₂₊) products offers an appealing route to store sustainable energy and make use of the chief greenhouse gas leading to climate change, i.e., CO ₂. Among potential products, C ₂₊ liquid products such as ethanol are of particular interest owing to their high energy density and industrial relevance. In this work, we demonstrate that Ag-modified oxide-derive Cu catalysts prepared via high-energy ball milling exhibit near 80% Faradaic efficiencies for C ₂₊ liquid products at commercially relevant current densities (>100 mA cm ⁻²) in the CO electroreduction in a microfluidic flow cell. Such performance is retained in an over 100-hour electrolysis in a 100 cm ² membrane electrode assembly (MEA) electrolyzer. A method based on surface-enhanced infrared absorption spectroscopy is developed to characterize the CO binding strength on the catalyst surface. The lower C and O affinities of the Cu–Ag interfacial sites in the prepared catalysts are proposed to be responsible for the enhanced selectivity for C ₂₊ oxygenates, which is the experimental verification of recent computational predictions.

Abstract

Here, the authors demonstrate a Cu-based catalyst with Cu–Ag interfacial sites, which favor oxygenate over alcohol production in CO ₂ electroreduction. Near 80% selectivity for multi-carbon liquid products in a 100 cm ² membrane electrode assembly electrolyzer is exhibited over 100 h.