Methyl orange as a novel colorimetric iodide indicator with in situ generation of H2O2 by etching uncoated Ag–Ti3C2 nanohybrids

Iodine intake remains a major public health concern, as both iodine excess and deficiency are related to adverse effects on health. Therefore, developing simple and economical methods to detect I − is still in great demand. Herein, we constructed a visual I − sensing platform based on the uncoated Ag–Ti 3 C 2 nanohybrids using methyl orange (MO) as a colorimetric indicator . Plasmonic nanostructures are frequently employed in colorimetric analysis , but uncoated Ag nanoparticles (NPs) are unstable because their surface energies are usually high. Considering that Ag NPs can be etched by I − via forming Ag–I bond, we introduce Ag–Ti 3 C 2 nanohybrids because uncoated Ag NPs with immaculate surfaces are more conducive to binding with I − and being etched. Dissolved O 2 molecules adsorbed on Ti 3+ of Ti 3 C 2 MXenes enable the in situ generation of H 2 O 2 by iodine-etching of uncoated Ag–Ti 3 C 2 nanohybrids. ∙OH radicals promote the degradation of MO through a self-driven Fenton-like process, exhibiting the color variation from orange to transparent. Under optimal conditions, the absorbance of MO at 465 nm decreases linearly with the concentration of I − in the range of 0.5–300 μM, with a limit of detection as low as 0.31 μM. This work opens the feasibility of iodine-etching of Ag in developing novel probes for facile colorimetric determination of I − .