Copper¹ and noble-metal alloys² have been shown to catalyze the electrochemical reduction of CO₂ to hydrocarbons such as methane (C₁) and ethylene (C₂). C₁ and C₂ hydrocarbons are the simplest building blocks for the synthesis of most industrial products and are therefore common chemical feedstocks. However, the production of hydrocarbons in aqueous solution is highly energy-consuming mainly due to the over-potential needed to overcome the transition states in C₁ and C₂ synthesis. In addition, there are significant efficiency losses due to the concomitant H₂ production that is kinetically and thermodynamically favored under these conditions. As ethylene and methane from fossil source are comparatively cheap, the high cost of electricity makes the production of these simple hydrocarbons prohibitively expensive.

We have developed a noble metal free catalyst that is able to reduce carbon dioxide to hydrocarbons at lower over-potentials than copper (-0.6 V vs RHE), with significant suppression of the hydrogen production compared to the CO₂ free environment. In addition, by changing the reactor configuration, CO₂ may now be converted to a valuable polymer with composition akin to an aldehyde-carbonate co-polymer. This solid product can easily be de-polymerized to its parent monomers by changing pH. The resulting complex organic acids and aldehydes produced in at only -0.9 V vs RHE, have a significantly increased value to the simple hydrocarbons making this a very promising technology.

Supported by the BASF Corporation Catalysis Division Fellowship.