Turning Color Confusion to Clarity: A Layered Ce-Based Nanozyme Drives Rapid Wavelength Transition for Discriminative Detection of Nerve Agent during Decontamination.

Organophosphate (OP)-based nerve agents (NAs) pose serious risks to human life, demanding materials that facilitate rapid decontamination and reliable detection with selectivity. Ce-based metal organic frameworks (MOFs) are considered as promising candidates due to their high reactivity. However, their intrinsic yellow color misleads detection of NAs such as paraoxon, which releases yellow p-nitrophenol. Here, we report a bioinspired 2D metal-organic layer (MOL) construct, Ce-BTB-MOL, a phosphotriesterase nanozyme with abundant binding sites that not only facilitate rapid degradation of paraoxon (t1/2 = 6 min), but quick detection by a smart mechanism. This nanozyme seamlessly arrests product with its binding to Ce clusters and triggering wavelength transition that overcomes color confusion, enabling quick and confident detection within 13 s on paper strips. Mechanistic studies reveal that p-nitrophenol binding to Ce clusters induces ligand-to-metal charge transfer (LMCT), producing an intense orange-brown signal. Based on the wavelength transition response, this nanozyme also showcases selective discrimination of structurally similar OPs, a challenge for conventional systems. Ce-BTB-MOL achieves real-time, affordable, portable, easy, and rapid sensing without the requirement of sophisticated equipment, with a detection limit as low as 1.24 µg, quantifiable by smartphone RGB analysis. Importantly, the nanozyme demonstrates high selectivity against several interferents, allowing precise surface contamination analysis.