High-performance, two-step/Bi-enzyme lactate biofuel cell with lactate oxidase and pyruvate oxidase

The performance of biofuel cells (BFCs) depends on the number of electrons that can be harvested from one fuel molecule by the bioanode, as well as many other factors. Regular, one-enzyme bioanodes can usually harvest two electrons per fuel molecule, lowering the conversion efficiency of chemical energy stored in the fuel to electrical energy. In this study, we successfully develop a high-performance BFC with a two-enzyme bioanode that can harvest four electrons by oxidizing lactate to acetylphosphate through a two-step enzymatic reaction that uses lactate oxidase (LOx) and pyruvate oxidase (POx). A current of 1 mA is obtained from the BFC for 2500 s, with only a slight decrease in the cell voltage, reaching 0 V at 3010 s. During this time, a total of 1253 mJ is harvested. This is approximately 1.8-fold the time and double the energy that is obtained from a corresponding one-enzyme-bioanode BFC employing only LOx, thus confirming that twice the number of electrons are harvested per lactate molecule.