The Construction Of Platinum Nano-Zinc Zeolite Imidazole Frame Composite And The Application In Mercury Ion Colorimetric Sensing Analysis

Mercury ion(Hg²⁺)is a kind of common heavy metal ion that is difficult to be degradated.Once the content of Hg²⁺is excessive,human living environment and health will be threatened and destroyed.Therefore,it is crucial to develop a simple and sensitive method for detecting Hg²⁺.In recent years,the colorimetric method has received wide attention because of its sensitive method,simple equipment,and qualitative or semi-quantitative analysis of the naked eye.In this paper,by using the excellent peroxide mimic enzyme activity of platinum nanocomposites,we established two kinds of novel colorimetric method of Hg²⁺detection:catalytic oxidation of peroxide substrate TMB and the etching action of gold nanorods?Au NRs?induced resonance?LSPR?peak shift with color change,respectively.The main contents of the research are as follows:1.The Pt NPs@ZIF-8 core-shell composite was prepared by coating the platinum nanoparticles?Pt NPs?with the porous structure of zinc zeolitic imidazole framework?ZIF-8?,and its morphology,structure,specific surface area and elemental composition were characterized.It was found that the prepared material possessed excellent peroxide mimic enzyme activity,and can catalyze the oxidation of TMB in the presence of hydrogen peroxide?H₂O₂?,while the presence of mercury ions can effectively inhibit the peroxidase activity of the material.Based on this,we have developed a new method based on Pt NPs@ZIF-8 colorimetric detection of mercury ions.Under the optimal experimental conditions,the decrease of TMB²⁺absorbance and the concentration of Hg²⁺showed a good linear relationship in the range of 5 nM-0.2?M,with a detection limit is 3 nM,which is comparable with other methods.The Hg²⁺recovery rate of actual water samples such as tap water and moat water is 93.2-101.4%,which is expected to be applied to the monitoring of future environmental water samples.2.In the presence of H₂O₂,the oxidation product TMB²⁺produced from Pt NPs@ZIF-8composite catalyzed the TMB oxidation can etch Au NRs,which will result in a blue shift of LSPR peak with obvious color change.Because of the specific inhibitory effect of Hg²⁺on the peroxide mimic enzyme activity of Pt NPs@ZIF-8 composite,we have established a new method for the determination of Hg²⁺in water by multicolor colorimetry based on Au NRs etching action.The experimental results show that the LSPR peak blue shift wavelength of Au NRs has a good linear relationship with the logarithm of Hg²⁺concentration in the range of 5 nM-1?M,and the detection limit is 1.5 nM,which is lower than the highest allowable concentration of Hg²⁺in drinking water regulated by the World Health Organization?WHO?.The Hg²⁺recovery rate of actual water samples such as drinking water and pond water is 96.4-104.3%.In addition,the method achieved a variety of color changes and is expected to be applied to on-site inspection of water quality.