Cd1-xZnxS biomineralized by engineered bacterium for efficient photocatalytic hydrogen production

The biomineralization process endows living microorganisms the ability to synthesize various inorganic nanomaterials with low cost, less environmental contamination, and good physicochemical properties. However, biosynthesis of band structure tunable photocatalysts is less investigated compared with traditional chemical synthesis methods. In this study, through varying the ratios of Zn2+/Cd2+ in the bacterial culture medium, a series of Zn-dopped CdS (Cd1-xZnxS) photocatalysts with various band structures are synthesized by engineered Escherichia coli with a surface-displayed biomineralization system. The bacterial-synthesized Cd1-xZnxS has an average particle size of <50 nm and are deposited on the bacterial cell surface. Through this strategy, significantly increased material loading is achieved. Under simulated sunlight, the biomineralized Cd1-xZnxS with a 0.044 molar ratio of Zn/Cd shows the highest photocatalytic hydrogen evolution rate (1,146 μmol/h/g), which is even better than that of the many chemically synthesized Cd1-xZnxS. Overall, biomineralizing heavy metal ions into band structure tunable photocatalysts via bacterial surface-display strategy is a promising approach to synthesize a series of band structure tunable nanomaterials for both energy conversion and environmental remediation purposes.