Enhancing solar-driven biological hydrogen production through a copper-based MXene-polypyrrole and Escherichia coli-integrated semiartificial photosynthetic system

The biohybrid-mediated semi-artificial photosynthetic system ingeniously combines the superior light-trapping characteristics of photosensitizers with the highly efficient catalytic capabilities of biocatalysts. However, the slow transfer of electrons at the micro-interface between the photosensitizer and biocatalyst is challenging for the performance of semi-artificial photosynthetic systems. Here, we report a semi-artificial photosynthetic biohybrid system comprising the positively charged hybrids of copper quantum dots/Mxenes encapsulated inside conducting polymer polypyrrole (Cu-MXene-PPY) and negatively charged Escherichia coli (E. coli) via electrostatic interaction. This system achieved an ideal state, wherein the photosensitizer possesses strong light absorption capability and a positive surface charge, enabling efficient electron transfer with E. coli. The semi-artificial photosynthetic system delivered a high catalytic performance for hydrogen production, with a yield of 2.37 mmol of hydrogen in 5 h (420–780 nm, 2000 W/m²). The mechanistic investigation of the catalysis indicated that the E. coli/Cu-MXenes-PPY biohybrids enabled inhibition of lactate production coupled with acceleration of formic acid production in bacteria under the influence of photoelectrons, which facilitated H⁺ reduction and H₂ production. Overall, this approach enables the construction of a robust semi-artificial photosynthetic system for H₂ production.