Self-sacrifficial Template Synthesis Of Alloy@Metal-organic Frameworks Core-shell Composite Nanomaterials And Their Properties

Recently,NP@MOFs nanocomposites with inorganic nanoparticles(NPs)embedded in metal-organic frameworks(MOFs)have attracted increasing research interests,owing to their unique structures and potential applications in many fields.As an emerging research area,there are still many problems in the structure-performance analysis of NP@MOFs and their applications.One of main reasons is that it is very difficult to controlled synthesis of NP@MOFs via commond methods such as encapsulation of pre-synthesized NPs by MOFs and in-situ formation of NPs in the pores of MOFs,which significantly limits the development of NP@MOFs in the study of their structure-performance and application.Self-sacrificial template is a solid-solid or solid-liquid interface reaction process,with slow reaction rate,so this method can not only theoretically control the nucleation of MOFs on nanoparticles,but also control the composition,morphology,shell ratio and other factors of NP@MOFs,eventually forming a one-by-one core-shell structure.In this dissertation,we explored controlled synthesis of NP@MOFs via a dealloying process by using alloy NPs as self-sacrificial template and studied their catalytic and absorption properties.The main results and conclusion are listed below:(1)We successfully fabricated core-shell PtCu3@MOF-74(Cu)by tuning the reaction temperature and other reaction conditions with excavated rhombic dodecahedral PtCu3 as self-sacrificial template.It was found that the matching between the etching rate of templates and coordination rate of metal ions is the key factor for the formation of NP@MOFs composites.In addition,the as-prepared PtCu3@MOF-74(Cu)can catalyze the hydrogenation of diphenylacetylene selectively,leading to the catalytic selectivity of cis-stilbene up to 100%benefiting from the synergistic effect of MOF-74(Cu)molecular sieve property and catalytic property of PtCu3.(2)Using magnetic ternary alloy Fe14(Co0.2Ni0.8)86 NPs as self-sacrificing template,we successfully prepared the magnetic core-shell structure Fe14(Co0.2Ni0.8)86@MOF-74(Ni)with different shell thickness,by controlling the reaction conditions(e.g.reaction temperature and reaction time).It was found that reaction temperature controls the composition and morphology of the product by affecting the equilibrium between the dissolution rate and coordination rate of Ni2+,while the reaction time determines the thickness of the MOFs shell.Consequently,this composite material can not only realize the efficient absorption of organic pollutants methylene blue(the maximum adsorption capacity can reach 15.1 mg/g),but also achieve efficient separation after adsorption,due to the combination of MOF-74(Ni)adsorption property and magnetic property of Fe14(Co0.2Ni0.8)86.