Interfacing Iodine‐Doped Hydrothermally Carbonized Carbon with Escherichia coli through an “Add‐on” Mode for Enhanced Light‐Driven Hydrogen Production

Abstract 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.