COnFinement of Formate dehydrogenases into ionic gas diffusion Electrodes for the Enzymatic conversion of CO2 – CO2FFEE

Carbon dioxide (CO2) should not be seen anymore as a waste but as an alternative carbon feedstock to produce platform chemicals and energy carriers. Amongst emerging strategies to produce valuable chemicals from CO2, biochemical processes provide promising alternatives, as they run on relatively mild conditions, are ecologically-friendly and highly selective. In particular, the formate dehydrogenase from Methylobacterium extorquens AM1 (MeFoDH1) has demonstrated superior CO2-reducing properties to convert CO2 into formate. However, MeFoDH1 requires a loosely bound cofactor, NADH, which is relatively unstable and expensive. To make such enzymatic reactors suitable for industrial applications, NADH-free alternatives must be developed. In this context, CO2FFEE will propose the synthesis of NADH-free enzymatic electrodes with high stability, superior CO2-reducing properties, and high selectivity. To do so, we propose to tackle a key challenge: to favor the direct electron transfer between MeFoDH1 and nanostructured graphene/ionic liquid electrodes. The design of molecularly engineered ionic liquids bearing multiple task-specific functionalities will allow preparing cutting-edge bio-hybrid gas diffusion electrodes with superior stability and electro-biocatalytic properties. By the end of the project, we expect to develop a NADH-free enzymatic flow electrolyser with high Faradaic efficiency (close to 100 %), high CO2 conversion yield, operational stability over several hours and competitive specific current densities superior to 100 mA/cm2. As-produced formate could be readily converted to formic acid which could be employed as a clean fuel for direct formic acid fuel cells or as a safe hydrogen storage material and therefore holds great potential in the current development of the hydrogen economy. Beyond formate, this project will be the first step towards multienzymatic cascade reactors to selectively produce methanol or other valuable chemicals.