Formate-Mediated Electroenzymatic Synthesis via Biological Cofactor NADH

Synthetic biohybrid systems by coupling artificial system with nature's machinery may offer a disruptive solution to address the global energy crisis. We developed a versatile electroenzymatic pathway for the continuous synthesis of valuable chemicals, facilitated by formate-driven NADH regeneration. Utilizing a bismuth electrocatalyst, we achieved stable CO₂ reduction to formate with approximately 90 % Faraday efficiency at a current density of 150 mA cm^-2. The generated formate acts as a mediator to regenerate NADH, which is then coupled with immobilized redox enzymes-alcohol dehydrogenase (ADH), L-lactate dehydrogenase (LDH), and L-glutamate dehydrogenase (GDH)-to produce targeted chemicals at significant rates and exceptionally high turnover numbers (1.8×10⁶ to 3.1×10⁶). These achievements not only underscore the efficiency of the system but also its practical applicability in industrial settings. By leveraging in situ generated formate, this innovative approach demonstrates the potential of integrating electrocatalysis with enzymatic reactions for sustainable and efficient chemical production on a practical scale.