Abstract
CO2 must be considered as a renewable raw material, an ideal molecule for storing renewable energies, first and foremost solar energy, in the form of renewable fuels such as methanol, methane or other hydrocarbons. To achieve this, we need to control and optimize the catalytic reduction ofCO2, either directly with light or with electricity from incident light, by overcoming the activation barriers required to transfer several electrons and protons (8 electrons and 8 protons in the case of methane, for example), in order to obtain the desired target with high selectivity. This remains a formidable challenge for chemists at the start of the 21st century [1]. Heterogeneous catalysis based on metals such as copper or carbonaceous materials doped with metal atoms has been explored with encouraging results, notably for obtaining carbon monoxide (CO) or formic acid (HCOOH), the 2-electron, 2-proton reduction products of carbon dioxide [2]. The selective, high-yield production of more reduced products, notably light hydrocarbons, remains problematic and poorly mastered, even if recent spectacular progress has been made [3].
In parallel, and unrelated to the previous approaches, molecular catalysis ofCO2 reduction has also been explored, mainly using transition metal complexes of low oxidation state, in particular with abundant metals such as Fe, Mn or Co. While excellent selectivities have been achieved for both CO and HCOOH generation [4], the production of more reduced products remains, as in heterogeneous catalysis, rare [5]. By combining molecular catalysts, which have the advantage of being selective, and carbonaceous materials, which are easy to structure down to the nanoscale and can confer enhanced stability on the system, it is undoubtedly possible to develop hybrid catalysts that can meet the challenges mentioned above. The seminar will survey the start of this long and steep road.
