A comprehensive study on rational biocatalysts and individual components of photobiocatalytic H2 production systems

Abstract

Photobiocatalytic system has been developing as a promising approach for H2 production. Herein, the rational characteristics of biocatalysts and the role of individual components affecting the efficiency of the system were investigated. Photocatalytic studies showed that tris (2-amino-2-hydroxymethyl-1,3-propanediol) was an ideal electron donor for viologen reduction by TiO2. Biocatalytic reaction revealed that cell permeability, the redox potential of electron mediators and the cell envelope were crucial to the activity of whole-cell biocatalysts. In photobiocatalytic system, recombinant Escherichia coli with a turnover frequency of 39.43 ± 3.77 s−1 based on [FeFe]-hydrogenase activity was a more rational biocatalyst than Anabaena variabilis. A comprehensive study found that the presence of TiO2, light and biocatalysts strongly enhanced H2 production, whereas Tris and MV2+ had less influence. A maximum rate was found at 16.73 ± 1.03 μmol/min with a solar-to-H2 conversion of 1.58 ± 0.10 %. Understanding the role of each component will guide the development of high-efficient photobiocatalysis.