Study On Degradation Performance Of Noble Metal Nanocomposites Based On Metal-organic Framework To Organic Dyes

New hybrid materials based on noble metal nanoparticles and metal organic framework（MOF）were designed and fabricated by the self-assembly methods,and their properties were discussed.Firstly,ZIF-8 MOF was prepared,and then MOF carriers of Co-N-C and Mn-N-C hybrid materials derived from Co-ZIF-8 and Mn-ZIF-8 were prepared respectively.Au Nanoparticles decorated on MOF carriers nanocomposites were prepared by diethylenetriamine（deta）as coupling agent.The obtained Au@Co-N-C and Au@Mn-N-C nanocomposites were characterized by some techniques in detail,and the catalytic performance of the new hybrid materials in dye degradation was discussed.The specific research work is as follows:（1）ZIF-8 metal organic framework of the typical analcite imidazoles was synthesized by using 2-methylimidazole and Zn（NO₃）₂ as precursors.Its structure and morphology were characterized by SEM,XRD and FT-IR.The results show that ZIF-8 has good dispersibility,homogeneity of particle size and regularity of dodecahedron contour.（2）The Co doped ZIF-8 MOF carrier was synthesized by using Co（NO₃）₂,Zn（NO₃）₂ and 2-methylimidazole as precursors.Gold nanoparticles（Au NPs）were supported on Co-ZIF-8 by in-situ growth by using HAuCl₄ as gold source and diethylenetriamine（deta）as coupling linker.Au@Co-N-C nanocomposites were prepared at 900℃in Argon atmosphere by calcining Co-ZIF-8.Their structure and morphology were characterized by SEM,TEM,XRD and XPS which proved that Au nanoparticles were well dispersed and loaded on the Co-N-C and the hybrid materials retained the dodecahedral morphology of Co-ZIF-8.The catalytic degradations of MB,MO,RB and 4-NP by Au@Co-N-C nanocomposites in aqueous solution were studied.The results confirm that Au@Co-N-C nanocomposites have good catalytic activity for MO and MB and the kinetic analysis of the catalytic degradation of MO and MB was also discussed.Its degradation effects on the four dyes is MO>MB>4-NP>RB and the catalytic degradation of MO and MB follow the first-order linear relationship.Besides,the stability and reusability of Au@Co-N-C were also evaluated.The results show that the catalyst still has good catalytic activity for MO and MB after 9 cycles of reuse.（3）Using Mn₂（CH₃COO）₃,Zn（NO₃）₂ and 2-methylimidazole as raw materials,Mn-ZIF-8 was synthesized by steam-assisted conversion method and chemical doping method,and then Mn-N-C was obtained by calcining Mn-ZIF-8 at 900℃under Argon atmosphere,and subsequently the as-synthesized Mn-N-C samples experienced acid leaching at 80℃to obtain the porous structure.With HAuCl₄ as the gold source,and DETA as the coupling agent,Au NPs（gold nanoparticles）were loaded on the Mn-N-C carrier through the adsorption force of Mn-N-C,finally the nanocomposites were calcined at 900℃under Argon atmosphere again to obtain Au@Mn-N-C nanocomposites.Their structure and morphology were characterized by SEM and TEM which showed that Au nanoparticles were well dispersed and loaded on the Mn-N-C metal-organic framework and the hybrid materials retained the dodecahedral morphology of Mn-ZIF-8.The catalytic degradations of MB,MO,RB and 4-NP by Au@Mn-N-C nanocomposites in aqueous solution were studied,from which we got that Au@Mn-N-C nanocomposites had good catalytic activity for MO and 4-NP,the kinetic analysis of the catalytic degradation of MO and 4-NP was also explored,furthermore,its degradation effects on the four dyes was MO>4-NP>MB>RB and the catalytic degradation of MO and 4-NP followed the first-order linear relationship.Moreover,the stability and reusability of Au@Mn-N-C were evaluated too.The results indicate that the catalyst still has good catalytic activity for MO and 4-NP after10 cycles of reuse.