High-Performance Colorimetric Detection of Hg²⁺ Based on Triangular Silver Nanoprisms

Mercury ion (Hg²⁺) arising from a variety of natural sources and industrial wastes has been widely recognized as one of the most hazardous pollutants. It is very important to develop highly selective and sensitive probe for rapid detection of Hg²⁺ in aquatic ecosystems. Here we propose a new strategy for high-performance colorimetric detection of Hg²⁺, i.e., anti-etching of silver nanoprisms (AgNPRs). In the absence of Hg²⁺, the AgNPRs can be etched by I^– inducing an obvious color change from blue to red. However, in the presence of Hg²⁺, the formation of Ag–Hg nanoalloy can protect the AgNPRs from I^– etching and the color remains blue. This mechanism is verified by UV–vis, TEM, DLS, and EDS. Our AgNPRs-based colorimetric probe exhibits excellent selectivity for Hg²⁺. The limit of detection (LOD) of Hg²⁺ is 30 nM by the naked eye and 3 nM by UV–vis spectroscopy, which is lower than the mercury toxic level defined by the U.S. Environmental Protection Agency (10 nM). A good linear relationship (<i>R</i>² = 0.993) between the wavelength shift and Hg²⁺ concentrations indicates that our probe can be used for the quantitative assay of Hg²⁺. The results of Hg²⁺ detection in real environmental samples indicate the feasibility and sensitivity of our probe for application in complicated environmental samples