Pyrolysis of Deep Eutectic Solvents for the Preparation of Supported Copper Electrocatalysts

Electrochemical CO₂ reduction on Cu-based catalysts can form a variety of products including hydrocarbons, alcohols and formate, besides carbon monoxide and hydrogen. Compared to other electroactive metals, copper has a rather low cost and low toxicity. We have developed a novel method for catalyst preparation using deep eutectic solvents (DES), where the pyrolysis of a metal-containing DES leads to a material consisting of a metal embedded in a carbon support rich in oxygen and nitrogen functional groups (CNO). We focus on the preparation of copper-based materials as catalysts for the electrochemical CO₂ reduction. Depending on the nature of DES, the properties of the carbon support can be changed. The electrochemical activity of the materials was correlated with the preparation parameters such as variation of DESs, copper precursor and/or pyrolysis temperature. These Cu/CNO copper catalysts showed formate formation rates up to 85.5 μmol h⁻¹ cm⁻² at 1.5 V vs. Ag/AgCl.