Light-driven, bias-free nitrogenase-based bioelectrochemical cell for ammonia generation

Area of Science:

• Biotechnology
• Electrochemistry
• Photochemistry

Background:

• Nitrogen fixation is essential for life, with nitrogenase being the key enzyme.
• Current methods for nitrogenase activation are energy-intensive.
• Harnessing light can reduce the energy demands of nitrogen fixation.

Purpose of the Study:

• To develop photo-bioelectrochemical cells (PBECs) for nitrogenase activation.
• To utilize light irradiation to lower the energy input for nitrogen fixation.
• To explore novel biotic-abiotic systems for value-added chemical production.

Main Methods:

• Constructed PBECs with BiVO₄/CoP and CdS/NiO photoanodes.
• Utilized glucose as an electron donor for nitrogenase activation.
• Employed fluorescence probe and ¹H-NMR spectroscopy for ammonia quantification.

Main Results:

• A BiVO₄/CoP based PBEC achieved efficient nitrogenase activation with minimal external bias (200 mV) and suppressed oxygen generation.
• A CdS/NiO based PBEC enabled bias-free nitrogenase activation, producing 100 μM ammonia with 12% faradaic efficiency.
• Demonstrated the feasibility of light-driven enzyme activation for chemical synthesis.

Conclusions:

• Developed novel PBECs for light-driven nitrogen fixation using nitrogenase.
• Established a foundation for biotic-abiotic systems to activate enzymes for chemical production.
• Showcased a sustainable and energy-efficient approach for ammonia synthesis.