Study On Preparation And Properties Of Photocatalytic Functional Cotton Fabric Based On Molybdenum Disulfide Modified Metal-organic Framework

In this study,molybdenum disulfide（MoS₂）was selected to modify two metal-organic frameworks to enhance their visible light catalytic activity.At the same time,the advantages of strong adsorption,high specific surface area and low cost of cotton fabrics are used as the carrier of the powder photocatalyst,which solves the problems of difficult recovery and poor recyclability of the powder photocatalyst.（1）A novel strategy for the preparation of efficient,durable and recyclable molecular sieve-imidazole framework-8（ZIF-8）-based photocatalytic materials is proposed through the modification treatment of MoS₂.ZIF-8 was prepared by layer-by-layer self-assembly on carboxyl cotton fabric.The carboxyl group of cotton fabric formed a coordination bond with the central metal ion of ZIF-8,which greatly enhanced the binding ability between particles and fabric.The semiconductor MoS₂was in situ grown on the surface of ZIF-8 to form a MoS₂/ZIF-8 heterojunction to improve the photocatalytic activity of ZIF-8.The morphology and elemental composition of the prepared MoS₂/ZIF-8/Carboxyl cotton was characterized by SEM,EDS,FTIR and XPS.The effects of layer-by-layer self-assembled ZIF-8 and MoS₂on the charge separation efficiency and optical properties of functional materials were investigated by electrochemical impedance spectroscopy and transient photocurrent spectroscopy.Under the irradiation of visible light,the prepared functionalized fabric has a good ability to degrade methylene blue.After 21 mins of visible light irradiation,the degradation rate of methylene blue in the simulated wastewater was about 99.8%.Furthermore,the photocatalytic degradation rate of the functional material remained about94.8%even after six uses.However,pure ZIF-8 has no visible light absorption band,and the photocatalytic degradation of methylene blue in aqueous solution is almost impossible under visible light.This chapter also proposes a possible mechanism for MoS₂to enhance the photocatalytic performance of ZIF-8.（2）Based on the formation of coordination bonds between Fe³⁺and-COOH,MIL-101（Fe）was grown in situ on carboxyl cotton fabrics,and then MoS₂was coupled with MIL-101（Fe）by a simple solvothermal method to prepare Efficient,reusable and photocatalytic materials with excellent heterojunction structure.The coordination bond formed by Fe³⁺and-COOH enhances the binding effect of MIL-101（Fe）and cotton fibers,and the heterojunction structure formed by the coupling of MoS₂and MIL-101（Fe）improves the photocatalysis of MIL-101（Fe）active.The morphology and properties of the prepared MoS₂/MIL-101（Fe）/Carboxyl cotton composites were tested by SEM,XRD and FTIR,which proved that MoS₂and MIL-101（Fe）grow uniformly on the surface of cotton fibers.The composites have good visible light absorption properties demonstrated by ultraviolet diffuse reflectance（UV-Vis DRS）.Electrochemical impedance spectroscopy and transient photocurrent responses demonstrate that the formed MoS₂/MIL-101（Fe）special heterostructure is beneficial for charge carrier separation efficiency and optoelectronic performance.MIL-101（Fe）was assembled on carboxyl cotton three times and irradiated with visible light for 24 mins.The degradation efficiency of MoS₂/MIL-101（Fe）/Carboxyl cotton functional material on methylene blue reached 99.79%.Under the same conditions,the degradation rate of methylene blue by pure MIL-101（Fe）is only 60%.In addition,the photocatalytic activity of the functional material still retains 91.09%even if the methylene blue aqueous solution is degraded for 6 cycles.Likewise,a possible mechanism for MoS₂to enhance the catalytic activity of MIL-101（Fe）is proposed.The preparation method used in this study shows great potential in developing textile-based multifunctional photocatalytic materials with high degradation efficiency and high recovery.The in-situ growth of metal-organic frameworks on cotton fabrics and the formation of heterojunction structures by semiconductor modification provides a new idea for designing efficient degradable and recyclable photocatalytic materials.