(322a) A Multi-Layer Gas Diffusion Enzyme Electrode for CO2 Reduction to Formate

Direct conversion of CO₂ to value-added chemicals, fuels and materials holds great promise for the effective reduction of CO₂ emission thereby mitigating global temperature increase. The high stability of CO₂ and low solubility are the major challenges to the chemical conversion of CO₂ in aqueous solution. Enzymatic conversion of CO₂, through intrinsically powered high affinity to the low concentration substrate and mildness of reaction, is suffered by the poor activity. Here we present an electro-enzymatic process for converting CO₂ into formate. A multi-layer gas diffusion bioelectrode was fabricated using formate dehydrogenase from Clostridium ljungdahlii (ClFDH), an enzyme featured as metal-dependent and oxygen-tolerant. CO₂ was converted to formate by direct electron transfer (DET) at this electrode. Carbon nanotube, polyaniline and gold nanoparticles, thiol self-assemble monolayer, ClFDH and polydopamine were deposited on the electrode. Polyvinylidene fluoride (PVDF) membrane serves as the gas diffusion layer. The mass and electron transfer of the gas-liquid-solid triphase interface and the chemistry of CO₂ activation by enzymes during the electrocatalysis process were examined, respectively, so to optimize the formate productivity.