Electrochemical CO2 and CO reduction reactions (CO2RR and CORR) offer ways to recycle CO2 and store renewable electricity into energy-rich chemicals traditionally produced from fossil resources. Liquid hydrocarbons from CO2RR and CORR such as formate, ethanol, acetate, and propanol are widely employed commodity chemicals with high energy density and offer straightforward storage and transportability. Therefore, we sought to develop electrocatalysts with high selectivity to formate and acetate at reaction rates (current densities) of interest for industrial applications. Inspired by the high selectivity to formate of indium-based catalysts and the high activities of nanostructured catalysts, we integrated thiol-capped InP colloidal quantum dots (CQDs) into gas diffusion electrodes for CO2RR. These cathodes generate formate as the only liquid product and H2 and CO as only gas products. Selectivity, measured as Faradaic efficiency (FE), maintained above 90% in the studied current density range (400-1000 mA cm-2, see Figure). Operando Raman and electrochemical characterizations, together with ex-situ XPS analyses, reveal that the active catalyst presents coexistence of metal indium and surface sulfur, which allows for the high selectivity and activity of this catalyst. Upgrade of CO to hydrocarbons favors high selectivity toward C2+ products. Furthermore, the low solubility of CO in alkaline electrolytes results in increased energy efficiencies when CO2RR-to-CO is followed by CORR-to-hydrocarbons. Therefore, we recently developed Cu-oxide-derived electrocatalysts that enhance the FE to C2+ liquid products, mainly acetate, at industrially relevant current densities.

High-rate CO2 and CO electroreduction to liquid hydrocarbons

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