Study On The Synthesis,Characterization,and Sensing Performance Of MOFs And Their Composites With CDs

Metal organic frameworks（MOFs）,as a porous material,have the advantages of large specific surface area,adjustable pore size,high thermal stability,and diverse structures.They are widely used in sensing,adsorption,catalysis,and other fields.MOF composite materials can achieve comprehensive properties that cannot be achieved by a single component material by complementing and correlating the properties of each component,For example,composite materials CD@MOFs Due to the combination of the advantages of CDs and MOFs,in the field of sensing,MOFs are either endowed with recognition performance that they did not originally possess,or the sensitivity and detection limit of MOFs as sensors are improved,It makes them a very promising material for application.Basis on it,this article focuses on the synthesis of MOFs and composite materials,as well as their applications in sensing.The main research works are as follows:1,Rare earth metal-based metal organic framework material Tb-MOF was prepared by solvothermal method.The study found that the suspension of this material in aqueous solution exhibited bright green fluorescence.When exposed to Cr（Ⅵ）solution,a strong fluorescence quenching phenomenon could be observed,and it had good sensitivity and anti-interference ability.Therefore,the Tb-MOF material can be developed as a sensor for detecting Cr（Ⅵ）,with linear ranges of 0-5.305μM,0-3.5μM for detecting CrO₄^2-and Cr₂O₇^2-,respectively.And the minimum detection limit can reach 3.5×10^-1μM and 2.6×10^-1μM.This concentration is lower than the highest international standard（0.5ppm）for Cr（Ⅵ）content in wastewater.2,Mn-MOF with layered structure was synthesized by hydrothermal method under high temperature and pressure.Then,using the same method,different volumes of carbon quantum dots were mixed with MOFs precursors to synthesize CD@Mn-MOFs.Experiments have shown that this composite material can be used as an electrochemical sensor to detect the content of hydrogen peroxide in aqueous solutions.It was found that the addition of carbon quantum dots not only improved the sensitivity of MOFs for detecting hydrogen peroxide,but also lowered the detection limit for hydrogen peroxide.Therefore,loading carbon quantum dots into MOF to synthesize composite materials is a good method to improve MOF performance.3,A layered bimetallic Co/Mn MOF was synthesized by hydrothermal method,and then the same method was used to synthesize CD@Co/Mn-MOF composite material.Experiments have shown that this composite material can be used as a fluorescence sensor for detecting the quinolone antibiotics in aqueous solutions.Taking norfloxacin as an example,the minimum detection limit of this composite material is 0.7μΜ,the minimum detection limit for Co/Mn MOF is 3.5μΜ.It can be seen that composite materials have reduced the minimum detection limit by 5 times compared to a single material.This experiment once again proves that loading carbon quantum dots is an effective way to improve MOF performance.