Photobiocatalytic H2 evolution of GaN:ZnO and [FeFe]-hydrogenase recombinant Escherichia coli
The need for sustainable, renewable and low-cost approaches is a driving force behind the development of solar-to-H2 conversion technologies. This study aims to develop new strategy using visible-light photocatalyst coupled to biocatalyst for H2 production. Photocatalytic methyl viologen (MV2+) reduction activity was investigated to discover active oxynitrides. In comparative studies with LaTiO2N, BaTaO¬2N and Ta3N5, it was revealed that the suitable surface area, band gap and band edge potentials are some physical factors that responsible for photocatalytic behaviors of GaN:ZnO on MV2+ reduction. The activity is enhanced at higher concentrations and alkaline pH of triethanolamine (TEOA). The expression of active [FeFe]-hydrogenase from Escherichia coli (Hyd+ E. coli) as a recombinant biocatalyst was confirmed by MV•+-dependent H2 production activity. In the photobiocatalytic system of GaN:ZnO and Hyd+ E. coli, the rate of H2 production reached the maximum level in the presence of MV2+ as an electron mediator at neutral pH as biocompatible condition. The present work reveals a novel hybrid system of H2 production using visible-light active GaN:ZnO coupled to Hyd+ E. coli, which shows the feasibility to be developed for photobiocatalytic H2 evolution under solar light.