Functionalized Mesoporous Photonic Crystal Film for Ultrasensitive Visual Detection and Effective Removal of Mercury (II) Ions in Water

Abstract

Mercury ion (Hg2+) contamination is a worldwide serious environment problem; exploring smart sensing and adsorption materials are urgently demanded for Hg2+ monitoring and removal. Herein, a simple 1D photonic crystal to first ever feature capabilities of visually quantitative determination and effective adsorption toward Hg2+ is facilely constructed by integrating a specifically designed thiourea-functionalized nanocopolymer layer with a mesoporous TiO2 layer. Based on strong chelation and porous structure, Hg2+ is easily adsorbed on the copolymer and triggers vertically volumetric shrinkage, resulting in highlighted wavelength blue-shifts and color changes in a broad Hg2+ level scope. Utilizing the adsorption characteristic, Hg2+ existing in aqueous media can be effectively removed by the photonic film with a remarkable uptake capacity of 739.6 mg g−1. This portable nanolayered film exhibits full regeneration, facile recovery, desirable selectivity toward Hg2+, and shields interference from other metal ions, which enables future application for environmental determination and remediation. Furthermore, a novel nanopolymer-based two-regime Hg2+-capturing mechanism is first revealed by quartz crystal microbalance with dissipation monitoring, providing valuable references for future relevant adsorption researches.