Carbonic Anhydrase-Inspired Zn-Single-Atom Nanozyme with High Stability for Enhanced CO₂ Hydration Performance

Efficient and durable catalysts are essential for enhancing the rate of CO₂ hydration in aqueous capture systems and addressing the environmental challenges posed by rising atmospheric CO₂ levels. Traditional capture methods that rely on strongly alkaline solvents face substantial drawbacks, including high regeneration energy costs and safety concerns owing to harmful byproducts. Carbonic anhydrase (CA), a zinc-containing metalloenzyme, catalyzes CO₂ hydration at near-diffusion-limited rates but rapidly degrades in real-world environments. Although various CA-mimetic catalysts have been investigated, they frequently exhibit poor durability and structural stability. In this study, we introduce ZnNC900, a robust Zn single-atom nanozyme derived from a zeolitic imidazolate framework (ZIF-8) through controlled carbonization. ZnNC900 exhibited remarkable catalytic activity for the p-nitrophenyl acetate esterase reaction, which was attributed to its CA-resembling single-atomic Zn sites. Furthermore, surface functionalization with amine-terminalized polyethylene glycol improves the colloidal stability and catalytic performance of ZnNC900 by enhancing its hydrophilicity and CO₂ affinity. These enhancements highlight the potential of ZnNC900 as a durable and efficient catalyst for aqueous CO₂ capture.