Carbon dioxide (CO₂) is considered one of the many greenhouse gases responsible for the global warming. Its average concentration in the atmosphere has already exceeded 400 ppm and it has been increasing since the beginning of the industrial revolution. Nowadays, the increase rate has been estimated to 2.3 ppm per years. Such value has called for stringent measures, in order to tackle this trend and reverse the loop in short time.

Among all greenhouse gases, CO₂ is inert but could represent an important source of carbon. The electrochemical conversion of CO₂ into value-added products presents an innovative way towards energy storage, while at the same time lowering CO₂ concentrations in the environment. However, lower overpotential, better selectivity and higher electrode’s lifetime are required to make the process economically viable. For such reasons, new electrocatalysts must be investigated and improved as soon as possible [1].

One of the best catalysts for electrochemical CO₂ reduction is metallic copper because of its capability to produce high quantities of hydrocarbons. Kuhl et al. reported 16 different products on a Sigma Aldrich copper electrode in a potential window comprised between E = -0.8 V vs. RHE and E= -1.2 V vs. RHE, among them 14 oxygenates products. Such result demonstrates that copper can be a promising catalyst because of its capability to promote selectively C-C coupling reaction pathways [2]. Up to now, however, only Shibata and coworkers [1] demonstrated different CO₂RR performances on Cu electrodes from different manufacturers: for Eurofysica^® copper electrodes, a wide range of hydrocarbons was obtained before electropolishing, whereas, with an electropolished electrode, only methane and ethylene were obtained. Instead, employing Alfa Aesar^® copper electrodes, methane and ethylene were the only products obtained, regardless of the use of an electropolishing technique [3].

In light of this result, we aim to investigate the electrocatalytic performance of copper electrodes from different suppliers, to provide a better understanding on what conditions affect the electrochemical reduction of CO₂ (CO₂RR) on copper foil electrodes. Furthermore, this study will provide additional benchmarking of CO₂ reduction on copper. In addition to Alfa Aesar® and Sigma Aldrich®, copper electrodes from Goodfellow^® and Mateck^® will be investigated. Several solid-state measurements will be carried out and linked to CO₂RR performance at E= -0.8 V, -1.0 and -1.2 V vs. RHE.

Additional parameters that will be taken into consideration are:

1) Grain size

2) Grain boundaries density

3) Crystallographic orientation of grains

4) Ratio of Copper oxides

5) Surface roughness