A heterologously-expressed thermostable Pyrococcus furiosus cytoplasmic [NiFe]-hydrogenase I used as the catalyst of H2/air biofuel cells.

Hydrogenase-catalyzed H 2 /air biofuel cells have attracted wide attention. However, how to obtain thermostable and highly active hydrogenase remains challenging. Herein, we developed a thermophilic archaea host system to heterologously express a thermostable Pyrococcus furiosus cytoplasmic [NiFe]-hydrogenase I (Pf SHI). The recombinant hydrogenase could be easily isolated and then immobilized onto a carbon nanotube-modified carbon felt electrode for further electrochemical characterization. The bioanode was able to work at a wide range of temperatures from 40 °C to 80 °C and no high potential deactivation was observed until 0.3 V at 50 °C. Cyclic voltammograms at elevated temperatures for reverse H 2 oxidation performance indicated that an inactive state might be formed and then reversed when scanning to negative position. Also, the power density of a whole cell reached 1.08 mW cm−2 using Pt/C as the cathode with a brilliant open circuit potential reaching 1.2 V. The voltage could retain 90% of its initial value after 33 h discharge at a current of 10 μA. Besides, the bioanode exhibited decent oxygen tolerance both in ambient and elevated temperatures. These results suggest that this recombinant Pf SHI can be a good candidate for catalyzing H 2 /air biofuel cells. • A method was developed to heterologously express a thermostable [NiFe]-hydrogenase. • The hydrogenase-catalyzed biofuel cell exhibited a good electrochemical performance. • The high-potential deactivation and the O 2 tolerance of the bioelectrode were discussed. [ABSTRACT FROM AUTHOR]