Ultrafine sulfur–doped carbon nanoparticles enhanced the transmembrane bioelectricity of Clostridium butyricum for biohydrogen production

Inorganic–biohybrid systems refer to the combination of inorganic nanoparticles with intact living cells, which have shown great potential in microbial fermentative hydrogen production. However, the typical whole–cell biohybrid systems often suffer from sluggish electron transfer and additional energy loss during transmembrane diffusion, which severely restrict the efficiency of hydrogen production. Herein, sulfur–doped carbon nanoparticles (SCNPs) are prepared by top–down laser–assisted synthesis. The inorganic–biohybrid system is constructed by assembling the SCNPs with the Clostridium butyricum cells. As expected, the biohybrid system has good viability and stability, and the H2 production of this biohybrid system is 12.5 times higher than that of the bare bacteria. Furthermore, the degradation efficiency of methyl orange by Clostridium butyricum is verified, while this hybrid system could reach over 90% in 12 h. In addition, the mechanism of enhancing hydrogen evolution is investigated. SCNPs engulfed by Clostridium butyricum have rich surface charges, which improve the efficiency of electron transduction in bacterial cells, accelerate the generation of pyruvate in bacteria, and enhance the activity of hydrogenase, thereby realizing H+ reduction and H2 generation. This method provides a simple and effective way to improve the electron transfer efficiency and reduce the energy loss in the transmembrane diffusion process to build a powerful whole–cell biohybrid system for hydrogen production.