Preparation Of MXene Nanosheets With Different Active Sites And Study On Its Energy Storage Performance

Ti₃C₂T_x MXene is a typical representative of the emerging two-dimensional layered transition metal carbide family.It has the advantages of metal conductivity,graphene-like structure,small band gap,and hydrophilicity of the functionalized surface.Therefore,the application of this two-dimensional material in the field of energy storage has received extensive attention.However,the electrochemical performance of MXene in different electrolytes is quite different,and there is currently no unified view on this issue.Therefore,this paper aimed at this scientific problem and proposes that effective active sites may be the key to determining the electrochemical performance of MXene.The new idea was to improve the electrochemical performance of MXene in aprotic electrolytes by regulating the effective active sites of MXene,and to clarify the energy storage mechanism of MXene in non-acid electrolytes.The main research contents of the thesis are as follows:（1）Surveyed on the effective active sites of MXene and its electrochemical performance.Prepared uniform MXene two-dimensional nanosheets,and used Na₂CO₃for intercalation.Through concentrated acid etching and heated treatment of the number of functional groups on the surface of the material to achieve the purpose of regulating the effective active sites of MXene,and to study its supercapacitor performance.Through the material morphology characterization,it was found that the material morphology did not change significantly before and after the intercalation,even after acid etching and heat treatment;the structure characterization showed that the effective active sites of MXene were adjusted through the surface interface to make the material structure change.The characteristic peak,（002）,has obvious red shifted and blue shiftde,and the element content and valence state also demonstrated regular changes.Performance tests showed that acid etching and heat treatment had a significant impact on material properties.After acid etching treatment,the specific capacitance of MXene in the neutral electrolyte could reach 88.15 F g-1 at a current density of 0.5A g^-1,which was 1.6 times that of the I-MXene sample,and even the IC-MXene sample The specific capacitance was 11 times,which proved that in Na₂SO₄ electrolyte,the electrochemical performance of MXene material is related to the effective active site.（2）Studying on the effective active sites of MXene and its electrochemical performance.Using the two-dimensional MXene sheet as the precursor,the Ti-C bond on the surface of the MXene sheet near the defect site could be broken by-OH ion attack through KOH,and the MXene sheet was cut into one-dimensional nanoribbons to achieve structural control.The morphology characterization showed that a relatively uniform one-dimensional nanobelt was successfully prepared by KOH shearing.The electrochemical performance test results demonstrated that at a current density of0.5A/g,the specific capacitance of the nanobelt sample is 81.2 F g^-1,which is 1.5 times that of the MXene sample,which further proved that the structure can effectively control the surface of the MXene material effective active site.