East China Normal University achieves high efficiency hydrogen production by live bacteria photocatalytically

On September 8, 2022, the team of Professor Zhang Zhonghai of East China Normal University and Associate Professor Zhang Wenming of Nanjing University of Technology jointly published a new study entitled “Living intracellular inorganic-microorganism biohybrid system for efficient solar hydrogengeneration” in the journal Joule.

The study observes for the first time the phenomenon of photo-enhanced biological hydrogen production on non-photosynthetic bacteria and non-genetically engineered bacteria, and constructs a non-metallic inorganic-biological hybrid system within cells, which integrates the excellent light absorption efficiency of inorganic semiconductors and the highly specific biocatalytic ability of microorganisms, and has great potential to become a sustainable and efficient platform for enhanced hydrogen production. The corresponding authors of the paper are Fu Baihe and Zhang Zhonghai; The first author is Wu Dan.

Efficiently collecting solar energy and converting it into chemical fuels, especially hydrogen, is a global challenge. However, the current efficiency of converting solar energy into hydrogen still does not meet the needs of the future hydrogen economy. The urgent need for renewable, sustainable and efficient hydrogen production is driving the rapid development of advanced technologies, and bio-hydrogen production based on whole-cell microorganisms is one of the most promising strategies.

Recently, The research group of Professor Zhang Zhonghai of East China Normal University reported a non-metallic inorganic semiconductor-microbial hybridization system in vivo, and C3N4QDs penetrated into E. coli (E. coli). coli), so that it can be photocatalyzed directly in bacteria, to achieve efficient catalysis of biomass hydrogen production. The work was the first to find that sunlight has an enhanced effect on biological hydrogen production by typical non-photosynthetic bacteria that have not been genetically engineered, and the experimental results overturn the traditional conclusion that light does not act on non-photosynthetic bacteria. NADH within bacteria acts as a molecular photocatalyst that enhances light-induced biomass hydrogen production. In addition, E. coli, as a living photocatalyst, can continue to multiply and grow in the reaction solution, prolonging the life of the catalyst.

Figure 1: E. Hydrogen production test and mechanism diagram of coli.

In order to further improve the interaction between light and non-photosynthetic bacteria, the study constructed a non-metallic inorganic semiconductor-microbial hybridization system in vivo, combining C3N4QDs with E. Coli co-culture, C3N4QDs have good biocompatibility and suitable size, easy to enter E by bacterial endocytosis. Inside the coli, an inorganic semiconductor-microbial hybridization system is formed. In E. In coli, C3N4 QDs/NAD+ junctions are formed through unique π-π electron conjugates, and a unique combination is formed between inorganic semiconductor quantum dots and live microbial photocatalysts, which effectively promotes the separation and transfer of photoelectrons, thereby achieving the highest hydrogen-producing activity.

Figure 2: Schematic diagram of the construction of a C3N4QDs/E. coli hybrid system.

The long-term stability and sustainability of the C3N4QDs/E. coli composite system is also important for the conversion of biomass to hydrogen. The complex system was tested for 50 h in a dark/light cycle, and no significant loss of hydrogen production activity was detected, which proved that the hybrid system had long-term stability. In long-term trials, bacterial viability is determined by colony-forming units (CFU), and E. coli remains 90% after 50 h of reaction (initial concentration is[5.0±0.4]×108 cells ml-1), the results confirm the superior biocompatibility of C3N4QDs. The C3N4QDs/E. coli hybridization system has a maximum conversion activity of ~7,800±12 μmol g-1h-1 (bacterial dry weight), which is 77% higher than the previously reported maximum value.

This study constructs an intracellular non-metallic inorganic-biological hybrid system as a living microbial photocatalyst, promotes the separation and transfer of optoelectrons, prolongs the life of the catalyst, thereby obtaining the maximum hydrogen-producing activity and revealing the advantages of in vivo hybridization system in hydrogen production. Inorganic semiconductor-microbial hybridization strategies in an alternative, more complex and more diverse way open up a new path for future improvements in solar conversion efficiency. (Source: Science Network)

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