Electrocatalysed carbon dioxide reduction

While many serious issues and problems now face the human population, perhaps the ones with the largest effects on the long-term viability and success of the planet’s inhabitants are those of energy availability and global climate change. These two issues are in part connected in a chemical sense via the simple carbon dioxide (CO₂) molecule.

For well over a century humans have been exploiting the cheap and abundant energy sources found naturally in liquid oil and gaseous hydrocarbons, with the dominant use serving as fuels for transportation needs. However, in addition to the energy produced, the total oxidation of hydrocarbons also produces CO₂ and H₂O as the ultimate chemical products. Every 4 liters of gasoline that is burned releases approximately 10 kilograms of CO₂ to the atmosphere. Levels of the known greenhouse gas CO₂ in the atmosphere are unquestionably increasing, and while there may be some debate about how much of the rise in concentration is man-made versus naturally-occurring, the fact remains that the levels are rising and are contributing to climate change. Therefore, it would be of critical interest to address both of these issues by removing CO₂from the atmosphere and transforming it into CO or some other small organic molecule that can be used as a transportation fuel precursor for recycle.

“Nickel(II) and Nickel(0) complexes of bis(diisopropylphosphino)amine: Synthesis, Structure and Electrochemical Activity” Dickie D. A., Chacon B. E., Issabekov A., Lam K., Kemp R. A., 2016, Inorg. Chim. Acta, 2016, 453, 42

Despite the view that main group (s and p block) elements are often considered relatively “simple” elements, Prof. Kemp has found in his previous work that unusual and surprising chemical behavior is often demonstrated by complexes of these metals.  

Ideally, our overall concept for the preparation of a new CO₂ electroreduction catalyst is to use a) an inexpensive, earth-abundant metal complex, in b) a solvent system that is “green” (ultimately water or ionic liquids), under c) mild conditions of temperature and pressure, to d) interact with and reduce CO₂ to either CO or other small molecules that can be converted into transportation fuels by known catalytic processes, e.g., Fischer-Tropsch, by e) using free electrons capable of being generated by renewable means such as electrochemistry.

The overall concept consists in making an electro-catalyst bearing a Lewis acid and a Lewis base.

Much to our delight, the first generation of electrocatalysts has proven to be efficient in reducing CO₂ into CO however the exact mechanism is still under investigation.

Our ultimate goal is the graft the catalyst on an electrode and to directly incorporate the electrogenerated CO into a valuable organic molecule.