Synthesis Of Two-Dimensional Transition Metal Carbide And Its Application In Electrochemical Detection Of Uranylion

Two-dimensional transition metal carbide（MXene）is a class of new layered nanomaterial with novel structure and unique properties,which has been widely used in environmental treatment,radionuclide removal and other fields.Due to its novel structure and unique characteristics,MXene-based materials has been widely explored in the applications of energy storage and environmental remediation fields.MXene materials have the advantages of large specific surface areas,abundant active adsorption sites,good hydrophilicity and controllable layer space,and such purely inorganic materials also exhibit excellent radiation resistance and good electrochemical properties,thus can be considered as ideal candidates for the electrochemical detection of radioactive element.Therefore,it has potential application value in the field of electrochemical detection of radionuclides.In this work,three different MXene materials were synthesized and their electrochemical detection performance against uranyl ions was investigated,and an electrochemical detection method for uranyl ions was established.The results are as follows:1.Three kinds of Ti₃C₂T_x MXene materials were synthesized.The preparation conditions of the three materials were optimized.And yield of the three materials have improved.The morphology and phase structure were analyzed.Multilayer Ti₃C₂T_x MXene material（M-Ti₃C₂T_x）was prepared by HF etching,single layer Ti₃C₂T_x MXene material（S-Ti₃C₂T_x）was prepared by LiF+HCL etching and ultrasonic peeling,and potassium ion alkali intercalated Ti₃C₂T_x MXene material（K-Ti₃C₂T_x）was obtained by KOH as alkali intercalation agent.Three Ti₃C₂T_x MXene materials were characterized by XRD,SEM and XPS.XRD results showed that all three materials were successfully synthesized with correct structure.SEM results show that M-Ti₃C₂T_x and K-Ti₃C₂T_x are multilayer accordion-like layered structures,while S-Ti₃C₂T_x is thin layer structure.XPS results showed that nano-sized titanium dioxide particles were formed on the surface of K-Ti₃C₂T_x.2.Three Ti₃C₂T_x MXene materials were loaded on glassy carbon electrode（GCE）using the classic titration coating method to obtain three Ti₃C₂T_x MXene modified electrodes:M-Ti₃C₂T_x/GCE,S-Ti₃C₂T_x/GCE and K-Ti₃C₂T_x/GCE.The electrochemical detection performance of three Ti₃C₂T_x MXene modified electrodes for trace uranyl ions(UO₂²⁺)was further studied.Cyclic voltammetry（CV）results showed that the electrochemical response of K-Ti₃C₂T_x/GCE modified electrode to UO₂²⁺was significantly enhanced compared with that of unmodified GCE electrode,M-Ti₃C₂T_x/GCE and S-Ti₃C₂T_x/GCE.The cyclic voltammetry results at different sweep velocities show that the electrochemical behavior of UO₂²⁺on K-Ti₃C₂T_x/GCE modified electrode is mainly controlled by diffusion,and the redox reaction occurs on the surface of the electrode.3.The reasons for the electrochemical response of U（VI）to K-Ti₃C₂T_x/GCE were explained by analyzing the changes of phase structure,end group content,isoelectric point and electron conduction rate of K-Ti₃C₂T_x materials before and after alkalization.K-Ti₃C₂T_x has a negative charge on its surface,and its multi-layer structure makes it have a larger surface area and more adsorption sites,which are conducive to the pre-adsorption and enrichment of UO₂²⁺cations.K⁺intercalation improves the interlayer stability of Ti₃C₂T_x MXene,thus eliminating the interference of capacitive effect of Ti₃C₂T_x MXene material in the electrochemical detection process.The alkali activation treatment of KOH increases the content of Ti-O and Ti-OH end groups on MXene surface and forms part of nano-sized titanium dioxide particles,thus providing more active coordination sites for UO₂²⁺and thus improving the electrochemical response of K-Ti₃C₂T_x/GCE to UO₂²⁺.The F-terminal group content of K-Ti₃C₂T_x MXene material decreased from 14.27%to 2.08%after intercalation,which was conducive to the increase of its electron conduction rate and the electrochemical detection of UO₂²⁺by K-Ti₃C₂T_x/GCE.4.Based on the above results,K-Ti₃C₂T_x/GCE was selected as the working electrode for the electrochemical detection of uranyl ions.Further,differential pulse voltammetry（DPV）scanning showed that at pH=4.0,the modified K-Ti₃C₂T_x/GCE electrode showed a good linear relationship for the detection of UO₂²⁺in the range of0.5-10mg/Luraniumconcentration.Thestandardcurvewas y（muA）=0.4356x（mg/L）+3.7375,and the correlation coefficient R²=0.997.The standard deviation of blank solution was calculated by 10 parallel measurements of the same blank control solution.The detection limit was 0.089 mg/L（S/N=3）with the standard deviation of 3 times blank solution as the detection limit.5.K-Ti₃C₂T_x/GCE was used as the working electrode to establish its electrochemical detection platform for uranyl ion.This method has low detection limit,high sensitivity,good stability and repeatability.In the future,it is necessary to further improve the selectivity,sensitivity and anti-interference ability of the electrode,so that it can be applied to the electrochemical detection of uranyl ion in actual water.At the same time,the electrochemical detection performance of other MXene materials on uranium,thorium and other more radionuclides can also be systematically explored,and the electrode materials with good selectivity and high sensitivity can be screened out.