Introduction

CO2 capture and storage, alongside transforming CO2 into alternative products, are methods aimed at slowing or even stopping the accumulation of CO2 in the atmosphere. Electrochemical conversion, thou very promising, is of non-immediate applicability due to the high stability of the CO2 molecule, the slow kinetics and the complex mechanisms of the CO2 reduction reaction. Among the numerous products of CO2 reduction, formic acid and carbon monoxide (CO) are the only economically viable products obtained with relevant productivity rates. However, the output of the process is usually a mixture of products, difficult or not easy to use industrially. In addition, the parasitic reaction of hydrogen evolution usually occurs in higher yield than the reduction of CO2 in aqueous electrolyte. Therefore, electrode materials are required that can provide high CO2 conversion efficiency and at the same time high selectivity towards a specific reaction product, in particular towards CO; materials of this kind are generally known in electrochemistry as electrocatalysts.

Technical features

The inventors have found that copper(I) oxide (CU2O, cuprous oxide) containing antimony (5 and 30% by weight), when used to produce an electrode coupled to an electrochemically conductive materials, such as carbon black, enables the electrochemical reduction of CO2 to CO to be achieved with higher values of faradic efficiency and selectivity than known materials. The electrocatalyst is obtained via the following steps:

1. Dissolving copper (II) salt and antimony (III) salt in a solvent selected from ethanol, ethylene glycol, acetylacetone, diethylamine, ethylenediamine, oleylamine, N,N-dimethylformamide, mixtures of these solvents with each other, with water or with aqueous solutions of D-glucose, hydrazine hydrate, amino acids or sodium carboxymethylcellulose;
2. Heating the solution in a microwave oven at a temperature between 180 and 230 °C for a time between 1 and 10 minutes;
3. Separating the precipitate from the solution and drying.

Possible Applications

• Carbon dioxide reduction;
• Production of CO for industrial applications.

Advantages

• High selectivity towards CO;
• Use of copper and antimony: inexpensive and widely available;
• Cost effective and scalable process.