Spray drying synthesis of stable Cu catalyst supported on carbon with high C2 product selectivity in CO2 electrolysis

Abstract

Electrocatalytic carbon dioxide (CO₂) reduction is an appealing option that offers advantages of converting greenhouse gas CO₂ into value-added hydrocarbon products while storing green energy. Copper (Cu) is a unique catalyst that has adequate ability for adsorption and activation of CO₂, as well as important intermediate species for forming multi-carbon (C₂₊) products. In particular, monovalent Cu(I) is deemed to be responsible for C-C coupling to form C₂₊ products. However, oxidation state copper species are unstable under the CO₂ electrolysis conditions, tending to be reduced along with surface reconstruction. It is therefore important to develop a robust catalyst synthesis method to enhance the stability of Cu-based catalysts. Here, we demonstrate a spray-drying method for the synthesis of carbon-supported Cu catalysts for the electrocatalytic CO₂ reduction reaction. This method is scalable and cost-effective, allowing one to realize mass production of carbon-supported Cu catalysts. A catalyst sample thus synthesized exhibits a Faraday efficiency of C₂ products (e.g., ethylene, ethanol and acetic acid) as high as 85.8 %. In-situ attenuated total reflection-surface-enhanced infrared absorption spectroscopy and surface-enhanced Raman spectroscopy characterization results reveal that the porous carbon support stabilizes Cu₂O/CuO nanoparticles, facilitate CO₂ adsorption, enrich local important intermediates for the C-C coupling reaction.