Hollow C@MoS2 nanotubes with Hg2+-triggered oxidase-like catalysis: A colorimetric method for detection of Hg2+ ions in wastewater

C@MoS2 nanocomposites with hollow nanotube structures were synthesized through the hydrothermal sulfuration of molybdenum precursor along with the carbonization of glucose. Interestingly, it was found that the so obtained C@MoS2 nanzymes could specifically exhibit much enhanced oxidase-like catalysis after the addition of Hg-2. Herein, carbon might not only play a role in accelerating charge transfer, but also conduct the synergistic effects with MoS2 to provide more catalytic active sites of nanzymes as compared with pristine MoS2. Especially, the introduction of Hg2+ could induce C@MoS2 nanozyme to produce more quantities of highly oxidative superoxide radicals through the strong Hg-S chelation in the catalysis reactions, as confirmed by the electron spin resonance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectra, and radical capturing experiments. A catalysis-based colorimetric platform with C@MoS2 nanozyme was thereby constructed for the quantitative analysis of Hg2+ ions, showing linear responses to Hg2+ in the range of 0.010-100 mu M with the detection limit of 2.7 nM, which is lower than those of current analysis methods. More importantly, the proposed colorimetric assay could be applied for detecting Hg2+ in environmental wastewater with the satisfactory detection recoveries, showing great potential applications for environmental monitoring, biomedical sensing, and food detection fields.