Preparation Of 1D Nanowire/MXene Composite Nanowire/MXene Composite And Its Application In Supercapacitors

At present,with the rapid development of industry and great assumption of fossil fuels,there is an increasing enthusiasm for researchers on renewable energy sources,among which the new efficient energy storage and conversion devices are the most critical part.As one of the new two-dimensional transition metal materials,MXene has attracted a lot of attention according to their outstanding electrical conductivity,large specific surface area,strong mechanical properties and high flexibility.Among MXene materials,Ti₃C₃T_xowing to the advantages of low toxicity,easy preparation and high stability has been widely used in the fields of energy storage.But the self-stacking of interlayers seriously hindered their practical application in supercapacitors.In order to solve the above problems,in this research,the one-dimensional nanowires were instered between the MXene Ti₃C₂T_x nanosheets to inhibited layers stacking.Bulk silver as a noble metal benefits from its superior electrical conductivity.Moreover,silver nanowires(AgNw)can effectively increase the specific surface area and facilitate electron transport.Nitrogen doped titanium dioxide nanowires(N-TiO₂Nw)which can be used as the cathode material for supercapacitors due to their stable chemistry,high surface and interfacial areas,over-negative redox potential and high hydrogen evolution overpotential.Composite nanomaterials have been prepared by combining two-dimensional MXene Ti₃C₂T_x nanosheets with one-dimension nanowires.Then the electrochemical performance of nanomaterials has been tested.This research provides a new method of Ti₃C₂T_x-based supercapacitors in practical application.The main research contents of this paper are as follows:1.MXene Ti₃C₂T_x nanosheets were prepared via in-situ synthesis,using hydrogen fluoride(HF)to etch MAX phase.AgNw was fabricated by polyol method,and Ag is growing along(111)plane in ethylene glycol.TiO₂ Nw was obtained by calcination of molten salt,then N-TiO₂Nw was synthesized by calcination of TiO₂Nw under N₂ atmosphere.2.The composite electrode material with different mass ratio of AgNw has been fabricated by mixing the AgNw with MXene Ti₃C₂T_x nanosheets in different proportions.The microtopography and internal structure of the composite materials were analyzed by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD)and Fourier transform infrared(FT-IR).The electrochemical test in the three-electrode system shows that the composite nanomaterials with the 5 wt%silver nanowire(M@5%AgNW)has the best electrochemical performance.The specific capacitance of composite nanomaterial electrode about 379.06 F g^-1 at the scanning rate of 10 mVs^-1,and 1 M H₂SO₄ as the electrolyte,with low charge transfer resistance.Besides,the capacitance retention reaches 98.2%after1,000 cycles at 10 A g^-1.These results have indicated that the MXene-based composite nanomaterials modified by AgNw possess excellent electrochemical properties and promising prospects.3.MXene/N-TiO₂ Nw composite nanomaterials have been prepared successfully by mixing MXene Ti₃C₂T_x nanosheets with N-TiO₂Nw in in different proportions.N-TiO₂ Nw established a network to improve surface area and the electrochemical performance of electrode.The appearance and internal morphology,structure,chemical composition and bonding force of materials were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),electron selection diffractometry(SAED),X-ray diffractometry(XRD),Fourier transform infrared spectroscopy(FT-IR)and Raman analyzer.X-ray photoelectron spectroscopy(XPS)was used to analyze the morphology and valence state of various element in the nanomaterials.The absorption properties of the material were analyzed by ultraviolet-visible spectrophotometry(UV-Vis).Cycle voltammetry(CV)test and galvanostatic charge-discharge(GCD)test declared that the mass ratio of N-TiO₂ Nw and MXene Ti₃C₂T_x in 7.5:1possessed optimum electrochemical performance.The mass specific capacitance of MT-7.5:1electrode has been calculated according to result about 208.78 F g^-1 at the current density of 1A g^-1,1 M H₂SO₄ as the electrolyte Electrochemical impedance(EIS)measurements of the composite electrode showed that the penetration of electrolyte was promoted,the recombination of nanosheets was inhibited,which benefited from the network of N-TiO₂ Nw established between MXene layers,greatly inhibited the re-stacking of nanosheets,accelerated the ion transport in the material and improved the electrochemical performance of the electrode which has provided new research ideas of MXene-based electrodes of supercapacitors.