Hydrogenases are nature's efficient catalysts for both the generation of energy via oxidation of molecular ​hydrogen and the production of ​hydrogen via the reduction of protons. However, their ​O₂sensitivity and deactivation at high potential limit their applications in practical devices, such as fuel cells. Here, we show that the integration of an ​O₂-sensitive hydrogenase into a specifically designed viologen-based redox polymer protects the enzyme from ​O₂ damage and high-potential deactivation. Electron transfer between the polymer-bound viologen moieties controls the potential applied to the active site of the hydrogenase and thus insulates the enzyme from excessive oxidative stress. Under catalytic turnover, electrons provided from the ​hydrogen oxidation reaction induce viologen-catalysed ​O₂ reduction at the polymer surface, thus providing self-activated protection from ​O₂. The advantages of this tandem protection are demonstrated using a single-compartment biofuel cell based on an ​O₂-sensitive hydrogenase and ​H₂/​O₂ mixed feed under anode-limiting conditions.

http://www.nature.com/nchem/journal/v6/n9/full/nchem.2022.html