Bioinspired Fe Single-Atom Nanozyme Synergizes with Natural NarGH Dimer for High-Efficiency Photobiocatalytic Nitrate...

Area of Science:

• Biotechnology
• Materials Science
• Environmental Science

Background:

• Nitrate reduction is crucial for ecosystem restoration and chemical industries.
• The conversion of nitrate to nitrite is a rate-limiting step.
• Existing methods face challenges in efficiency and selectivity.

Purpose of the Study:

• To develop an efficient semiartificial photobiosynthetic platform for light-driven nitrate reduction.
• To overcome the kinetic bottleneck in nitrate-to-nitrite conversion.
• To provide a sustainable source of nitrite for anammox reactions and ammonia production.

Main Methods:

• Combining cyano-rich carbon nitride (C3N4)-supported Fe single-atom nanozymes (Fe/C3N4-CN) with native NarGH dimers.
• Utilizing visible light irradiation to drive the nitrate reduction process.
• Conducting mechanistic studies at atomic and molecular levels to understand electron transfer pathways.

Main Results:

• Achieved state-of-the-art nitrate conversion with nearly 100% nitrite selectivity.
• Observed an unprecedented reaction kinetic constant (k), significantly outperforming existing photocatalysts.
• Demonstrated a 68.9-fold enhancement in catalytic activity compared to isolated C3N4 photocatalysts.
• Reported a synergized enzymatic catalytic efficiency (kcat/KM(app)) of 1.81 × 10^6 M^-1 min^-1, surpassing biological enzymes and mimics.

Conclusions:

• The Fe/C3N4-CN and NarGH dimer system effectively mimics the NarI subunit's electron transfer function.
• A unique electron transfer chain at the biotic-abiotic interface enables efficient nitrate reduction.
• This approach offers a promising solution for sustainable nitrite production and reduced energy consumption in chemical processes.