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

Abstract

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 A(563 nm)/A(631 nm) were linear in proportion to the ClO2- concentrations with two different slopes in the ranges 0.00-0.06 mu M and 0.075-0.15 mu M, 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.