Efficient Synthesis of Pyruvic Acid from Biomass based on Gas-Liquid-Solid Triphase Bioelectrochemical Cascade Reaction

The enzymatic synthesis of pyruvic acid (PyA) from biomass-derived lactic acid (LA) using oxidases under mild conditions represents a promising sustainable route. However, its efficiency is hindered by insufficient O 2 mass transfer and undesired PyA degradation resulting from the enzymatic byproduct H 2 O 2 . Herein, we present an gas-liquid-solid triphase bioelectrochemical reaction system that can address these two challenges symmetrically. This design ensures an efficient supply of O 2 from the air phase to the lactate oxidase (LOx) active zone, thereby overcoming the mass-transfer constraint of oxygen. Simultaneously, the in situ electro-oxidation of H 2 O 2 minimizes the degradation of PyA. Consequently, the reaction system achieves a production rate of 54.34 µM h −1 U −1 , which is 63-fold greater than that of conventional liquid-solid diphase enzymatic systems. Mathematical modeling and electrochemical studies revealed that enhanced local O 2 levels and efficient H 2 O 2 removal are the keys to superior performance. This work provides a sustainable and efficient route for PyA biosynthesis while demonstrating the potential of engineered bioelectrocatalytic environments for green synthesis. Graphical A triphase (air–liquid–solid) bioelectrochemical cascade reaction system is utilized for enzyme-catalyzed pyruvate production. This approach effectively overcomes the challenges of hypoxic conditions and pyruvate oxidation in the presence of H 2 O 2 . Compared to the conventional diphase enzymatic system, the formation rate in this triphase bioelectrochemical cascade system is enhanced by a factor of 63.