Understanding the local chemical environment of bioelectrocatalysis

Significance Enzyme bioelectrochemistry concerns the integration of oxidoreductase enzymes into electrodes to enable and study the transfer of electrons between the solid-state material surface and the biological catalyst. To achieve higher enzyme loading, and hence greater current densities, high-surface-area strategies have been employed to immobilize enzymes, but these porous electrode architectures amplify the formation of local chemical gradients. Enzyme selectivity and activity is highly dependent on such changes in local environment, such as substrate concentration, pH, and electrolyte species concentration. Here, electrochemistry and computational techniques are applied to explore, and hence optimize, the local environment of the fuel-producing oxidoreductases, hydrogenase and formate dehydrogenase, within porous electrodes.