Preparation Of Photothermal Graphene-based Composites And Their Catalytic Properties

Chemical warfare agents(CWAs)pose a huge threat to humans and the environment due to their high toxicity.Research on composite nanomaterials capable of capturing and further destroying CWAs has important theoretical significance and broad application prospects for improving the overall level of China’s protective equipment.Metal organic framework(MOFs)compounds have high specific surface area and mouldability,as well as abundant adsorption and catalytic sites,which can effectively capture and rapidly catalyze the degradation of CWAs.Graphene has unique advantages in the field of multifunctional protective materials due to its light weight,high specific surface area,excellent broad-spectrum adsorption performance,good light absorption and photothermal conversion capability.In this paper,a zirconium-based MOFs materials UiO-66-NH2 are in situ loaded on graphene two-dimensional and three-dimensional supports,and the photothermal conversion effect of graphene is utilized to enhance the catalytic degradation performance of the nerve agents simulant methyl paraoxon(DMNP).Furthermore,taking advantage of the confinement effect,we designed smaller nano-MOFs catalytic particles grown on porous graphene aerogel and make full use of the synergy between adsorption and catalysis to achieve dual goals of high catalytic degradation efficiency and long-term stability.Simultaneously,a systematic study on the catalytic hydrolysis reaction mechanism of DMNP is made.The main research work is as follows:(1)Photothermal graphene/UiO-66-NH2 fabric for ultra-fast catalytic degradation of chemical warfare agent simulants:Photothermal graphene-based nanocomposite fabrics were designed by wet-spinning and partial chemical reduction and vacuum filtration of graphene oxide fibers followed by in situ growth of UiO-66-NH2.The fabrics exhibited an ultrafast photothermal catalytic decontamination of DMNP with the half-life of 3.4 min.Under simulated solar light irradiation,the photothermal conversion and instantaneous heat transfer of graphene to UiO-66-NH2 catalyst effectively accelerated the catalytic reaction kinetics,and the half-life of degradation reaction decreased to 1.6 min.The degradation rate was superior to the MOF-based catalytic fabrics reported in the international literatures.In addition,the composite fabrics showed satisfactory recycling ability,and the catalytic degradation efficiency remained over 92%after 5 cycles.The catalytic degradation process and product of DMNP hydrolysis in alkaline buffer solution were studied by chromatography and nuclear magnetic method.Combined with the relevant progress of the literature,the catalytic hydrolysis mechanism of DMNP by catalysts was proposed.(2)Preparation of three-dimensional graphene confined MOF hybrid materials and the catalytic degradation of chemical warfare agent simulants:In this study,graphene/MOFs hybrid materials were prepared by in situ growth of nano-scale UiO-66-NH2 MOFs particles on graphene sheets by facile hydrothermal and solvothermal methods.Because of the confined effect,the diameter of MOFs particles decreased to about 35 nm.In addition,the synergy between the graphene aerogel and MOFs,and photothermal effect of graphene,improved the catalytic degradation efficiency of three-dimensional composite materials,the degradation half-life is 1.8 min.Furthermore,the hybrid materials still maintain excellent catalytic activity after 5 cycles.