Highly sensitive chlorite ion sensor developed on the basis of etching of incurvate gold nanohexahedrons

Incurvate gold nanohexahedrons (AuNHs) are feasible colorimetric probes for the monitoring of chlorite (ClO2−) ions. In this study, incurvate AuNHs were found to respond to ClO2− ions selectively, and the addition of ClO2− ions to water samples induced selectively the etching of incurvate AuNHs, eroding the sharp apexes to rounded edges, which brought in hypsochromic shift absorption attended by a color alternation from cobalt blue to violet pink. The process of etching of incurvate AuNH vertices was characterized using X-ray photoelectron spectroscopy and atom probe tomography. ClO2− ions were successfully detected using the incurvate AuNH-based probe at pH 2.0 and 25 °C with 20 mM NaCl. The A563 nm/A631 nm were linear in proportion to the ClO2− concentrations with two different slopes in the ranges 0.00–0.06 μM and 0.075–0.15 μM, and detection limits of 3.03 and 3.27 nM in tap water and waste water, respectively. The hypersensitive and selective optical assay reported herein has been excellently implemented to determine ClO2− concentrations in spiked tap water, waste water, Clorox cleaning solution, and disinfecting wipes.