Atomically dispersed N-coordinated Fe-Fe dual-sites with enhanced enzyme-like activities

Replacement of enzymes with nanomaterials such as atomically dispersed metal catalysts is one of the most crucial steps in addressing the challenges in biocatalysis. Despite the breakthroughs of single-atom catalysts in enzyme-mimicking, a fundamental investigation on the development of an instructional strategy is still required for mimicking biatomic/multiatomic active sites in natural enzymes and constructing synergistically enhanced metal atom active sites. Herein, Fe₂NC catalysts with atomically dispersed Fe-Fe dual-sites supported by the metal-organic frameworks-derived nitrogen-doped carbon are employed as biomimetic catalysts to perform proof-of-concept investigation. The effect of Fe atom number toward typical oxidase (cytochrome C oxidase, NADH oxidase, and ascorbic acid oxidase) and peroxidase (NADH peroxidase and ascorbic acid peroxidase) activities is systematically evaluated by experimental and theoretical investigations. A peroxo-like O₂ adsorption in Fe₂NC nanozymes could accelerate the O–O activation and thus achieve the enhanced enzyme-like activities. This work achieves the vivid simulation of the enzyme active sites and provides the theoretical basis for the design of high-performance nanozymes. As a concept application, a colorimetric biosensor for the detection of S^2– in tap water is established based on the inhibition of enzyme-like activity of Fe₂NC nanozymes.