Triangular silver (Ag) nanoplates with sharp corners exhibit fascinating optical properties, but their triangular shapes are not thermodynamically stable. However, this intrinsic instability can be used to realize novel applications. In the current work, we designed such application, one in which the spontaneous rounding of the sharp corners of the Ag nanoplates exposed to bromide ions (Br<sup>-</sup>) was used to develop a novel sensing platform for the quantification of water in water-ethanol mixtures. The rate of change of the color and spectral features of a water-ethanol mixture containing Ag nanoplates resulting from the introduction of KBr was found to be strongly correlated with the volume fraction of water in the mixture. This relationship, which was attributed to the previously determined dependence of the solubility of KBr on the volume fraction of water in water-ethanol mixtures, allowed for the quantification of water in water-ethanol mixtures having any water volume fraction (from 0 to 1.0). This colorimetric sensing platform exhibited reliable sensing results in real water-ethanol mixture samples and it was also successfully applied to determining the relative amount of water in water-isopropyl alcohol mixtures, suggesting that it could furthermore be applied to mixtures of water and other alcohols as well. We believe that the nanocrystal-based sensing platform holds great potential for use as a point-of-care analytical tool for the quantification of water in the fine chemical, pharmaceutical, and food and beverage industries.

Metal nanocrystal-based sensing platform for the quantification of water in water-ethanol mixtures

2019 Spring National Meeting

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