β-Cyclodextrin and graphene oxide co-strengthened AgRu bimetal mesoporous nanozyme: An efficient strategy for visual detection and removal of toxic Hg2+ and Cl−

Abstract

In this work, to efficiently eliminate the threat of toxic Cl− and Hg2+, a kind of AgRu bimetal mesoporous nanozyme co-stabilized by β-cyclodextrin and graphene oxide (AgRu@β-CD-co-GO) was first developed by a homogeneous redox and assembly method. The mesoporous microstructure and a large number of hydroxyl groups and GO aryl rings endowed AgRu@ β-CD-co-GO with superior peroxidase-mimic performance and enough active spots to adsorb more toxic Cl− and Hg2+. Under optimal conditions (pH 4.0, 350 μL 1.5 mM TMB and 200 μL 1.0 M H2O2 and incubated for 30 min at 25 °C), AgRu@ β-CD-co-GO could accelerate the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into blue oxTMB in the presence of H2O2. Toxic Cl− or Hg2+ would exclusively alter its peroxidase-like activity, accompanied with the characteristic UV–vis absorption intensity at 653 nm (A653) decreased and color changed from blue to colorless. AgRu@ β-CD-co-GO was successfully applied for visual detection of Cl− and Hg2+ and enriched removal of them after their detection. The detection limits were low to be 3.2 × 10−10 mol∙L−1 for Hg2+ and 6.4 × 10−8 mol/L for Cl−. After detection, more than 94.9% Hg2+ and 93.8% Cl− could be removed by only a simple filtration. The mechanisms for peroxidase-mimic activity of AgRu@ β-CD-co-GO and its exclusive recognition of Hg2+ and Cl− were proposed.