Extracellular self-photosensitizer combined with metal oxide-based nano bio-hybrid system encapsulated by alginate improves hydrogen production in the presence of oxygen.

The photocatalytic nano-biohybrid systems have great potential for the conversion of solar energy to fermentative hydrogen production. Herein, a whole-cell nano-biohybrid system consisting of biosynthesized cadmium sulfide, Enterobacter aerogenes cells, and metal oxide nanoparticles was constructed. The system was encapsulated with sodium alginate and used for light-driven biohydrogen production under anaerobic and in the presence of oxygen conditions. After 48 h incubation in the presence of oxygen, the E. aerogenes cells with the encapsulated hybrid system yielded 2.7 mmol H2/mmol glucose, a 13.5-fold higher than that of the E. aerogenes cells without encapsulation. The encapsulated hybrid system could produce hydrogen for up to 96 h and could produce hydrogen even under natural sunlight conditions. These results revealed that efficient hydrogen production is possible in the presence of oxygen. Overall, the present study demonstrated the potential of using proper nano-biohybrid system with encapsulation for the production of hydrogen under ambient air condition.