Research On Preparation Of Mxene Based Nanomaterials And Their Application In

As a new type of two-dimensional nanomaterial,MXene(Ti₃C₂)is exensively used in the field of photocatalysis owing to its layered structure and excellent charge transport properties.The layered structure of MXene nanosheets and the size effect of quantum dots contribute to the construction of photocatalysts and provide a large number of active sites required for photocatalytic reactions.However,due to the narrow band gap of MXene,the rapid recombination of electrons/holes,and the low utilization rate of visible light,which greatly limits its application in photocatalysis.In the current photocatalysis research,MXene is often used as a co-catalyst synergistic with other materials in Photocatalytic.Based on previous studies,this article starts from the preparation of MXene nanomaterials,and aims at fast electron-hole recombination and insufficient use of visible light disadvantages.It improves photocatalysis by recombining with other band gap-matched semiconductor materials.expanding the application prospects of MXene in photocatalysis.The specific work is summarized in the following three aspects:(1)TiO₂@Ti₃C₂ nanocomposites were prepared by hydrothermal method.Using Na BF₄ as the crystal surface modifier,TiO₂ nanosheets were grown in situ on the Ti₃C₂ surface,and the TiO₂ nanosheets were randomly distributed on the MXene surface to construct a unique heterostructure photocatalyst TiO₂@Ti₃C₂.According to the degradation experiments of organic dye under full spectrum,visible light and Ultraviolet light,we found that TiO₂@Ti₃C₂ nanocomposites all have different extents of promotion effect on the degradation of Methyl orange(MO),The hydrothermal temperature at 160?,TiO₂@Ti₃C₂composite has the best photocatalytic degradation performance.The degradation efficiency of MO can reach 97.00%under Ultraviolet light.(2)The g-C₃N₄ and TiO₂@Ti₃C₂(160?)nanocomposite materials were combined by mechanical grinding.and the successful preparation of TiO₂@Ti₃C₂/g-C₃N₄ photocatalyst was proved by XRD and HRTEM.The characterization of SEM,TEM and BET found that g-C₃N₄ is closely combined with TiO₂@Ti₃C₂ and is distributed in the loose layered structure of TiO₂@Ti₃C₂.The large enough specific surface area of g-C₃N₄ ensures the smooth progress of the photocatalytic reaction.The UV-Vis absorption spectrum showed that:TiO₂@Ti₃C₂ significantly improved the visible light absorption capacity of g-C₃N₄.The photocatalysis experiment found that:the calcination temperature is 100?,the ratio of TiO₂@Ti₃C₂:g-C₃N₄ is 20%,the degradation rate of the Methylene blue(MB)under visible light reaches 99.62%,and the NO removal has good selectivity in the meantime.Finally,the photocatalytic reaction mechanism of NO removal was proposed according to capture experiments.Based on the electro-chemistry and Mott-Schottky test,the tight combination of TiO₂@Ti₃C₂/g-C₃N₄ heterojunction improves the segregation rate of electrons and holes.The combination with TiO₂@Ti₃C₂ increases the visible light absorption coefficient of g-C₃N₄ and achieves higher NO removal activity and selectivity.(3)The Bi OI,g-C₃N₄ and Ti₃C₂ quantum dots were carried by the water bath method,and the XRD and HRTEM characterization indicated that the photocatalyst Bi OI/g-C₃N₄/Ti₃C₂QDs were successfully constructed.SEM,TEM and BET proved that the composite of Ti₃C₂ QDs offer the catalyst a larger specific surface area and provided a large number of reactive sites.The UV-Vis absorption spectrum showed that Bi OI caused a significant red shift of the g-C₃N₄ absorption band edge,which significantly improved the visible light absorption capacity of the photocatalyst.The photocatalytic results showed that the NO removal activity of Bi OI/g-C₃N₄/Ti₃C₂ QDs was significantly improved,reached 46.92%.cycling experiments showed that Bi OI/g-C₃N₄/Ti₃C₂ QDs not only have a high removal rate of NO,but also have good cycle stability.Subsequently,based on the capture experiment and the M-S plots,the photocatalytic reaction mechanism of NO removal is proposed as follows:Bi OI and g-C₃N₄ have established a close relationship,and the built-in electric field is conducive to the rapid separation and transfer of electrons/holes,more reactive groups generated to participate in the process of NO removal,the p-n heterojunction photocatalyst ultimately displayed higher NO removal efficiency.