Bioinspired Fe Single-Atom Nanozyme Synergizes with Natural NarGH Dimer for High-Efficiency Photobiocatalytic Nitrate Conversion
Jiyong Bian, Jing Zhao, Zixuan Zhang, Dongfei Liu, Xianen Lan, Yang Liao, Xiaoqiang An, Diannan Lu, Minmin Liang, Ruiping Liu, Junwang Tang, Huijuan Liu, Jiuhui Qu
Abstract
Nitrate reduction is of paramount importance for both the restoration of natural ecosystems and the sustainable development of chemical industries but faces challenges in the rate-limiting step of nitrate-to-nitrite conversion. Herein, we demonstrate a semiartificial photobiosynthetic platform that synergistically combines cyano-rich carbon nitride (C 3 N 4 )- supported Fe single-atom nanozymes (Fe/C 3 N 4 –CN), which mimic the electron transfer function of the NarI subunit, with native NarGH dimers for efficient light-driven nitrate reduction. Under visible light irradiation, the photobiocatalyst exhibits a state-of-the-art capability for nitrate conversion with nearly 100% nitrite selectivity and an unprecedented reaction kinetic constant ( k ) that far exceeds those of all reported visible-light-driven photocatalysts, corresponding to a 68.9-fold enhancement over the isolated C 3 N 4 photocatalysts. The synergized enzymatic catalytic efficiency ( k cat / K M (app)) reaches 1.81 × 10 6 M –1 min –1, far exceeding those of reported biological enzymes and enzyme-mimicking nanomaterials for nitrate conversion. Mechanistic studies at the atomic and molecular levels reveal that Fe single atoms and −C≡N groups on C 3 N 4 mimic the heme b D and heme b P in the NarI subunit, forming a unique electron transfer chain between the biotic–abiotic interface that enables efficient nitrate reduction. This work represents an inspiring approach to overcome the kinetic bottleneck of nitrate-to-nitrite conversion, providing essential nitrite for sustainable anammox reactions and reducing energy consumption for ammonia production.