The recently emerged photosynthetic biohybrid systems (PBSs) integrate the advantages of the light‐harvesting ability of semiconductors and the catalytic power of biological metabolism. Herein, negatively charged iodine‐doped hydrothermally carbonized carbon (I‐HTCC) is interfaced with surface modified Escherichia coli cells through a facile “add‐on” mode via electrostatic interactions. As a result of the photoexcited electrons, the self‐assembled I‐HTCC@E. coli biohybrid shows enhanced hydrogen production efficiency with a quantum efficiency of 9.11% under irradiation. The transduction of photoelectrons from I‐HTCC to cells is the rate‐limiting step for H2 production and is delivered through both direct injection and the NADH/NAD+‐mediated pathways. The injected photoelectrons fine‐tune the H2 production through the formate and NADH pathways in a subtle manner. The excellent biocompatibility and photostability of the I‐HTCC@E. coli biohybrid demonstrate its potential real‐world application under sunlight. In addition, the proposed “add‐on” mode is extended to a series of negatively charged common carbon‐based materials with different levels of promotion effects compared with that of pure bacterial cultures. This facile and effective mode provides an insight into the rational design of the whole‐cell PBSs with various semiconductors for H2 production.

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Klebsiella pneumoniae with crude glycerol-utilizing and hydrogen (H2)-producing abilities was successfully isolated from return activated sludge from Shatin Sewage Treatment Works. The H2 production strategy used in this study was optimized with crude glycerol concentrations, and 1,020 μmol of H2 was generated in 3 h. An inorganic–microbe hybrid system was constructed with metal-free hydrothermal carbonation carbon (HTCC) microspheres to enhance the H2 production under visible light (VL) irradiation. Under optimized VL intensity and HTCC concentration, an elevation of 35.3% in H2 production can be obtained. Electron scavenger study revealed that the photogenerated electrons (e–) from HTCC contributed to the additional H2 production. The variation in intercellular intermediates, enzymatic activity, and reducing equivalents also suggested that the photogenerated e– interacted with K. pneumoniae cells to direct the metabolic flux toward H2 production. This study demonstrated the feasibility of using an inorganic–microbe hybrid system as a waste-to-energy technology.

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