Construction And Application Of Transition Metal Nanocomposites

Nanotechnology has received universal attention worldwide and has been rapidly developed in recent years.It is regarded as an important support for leading the future development of science and technology,leading the new industrial revolution and triggering changes in production methods.Nanotechnology has broad application prospects in the fields of production,life,medicine and health,and aerospace.The design and construction of high-performance nanomaterials is the cornerstone of the development of nanotechnology.By adjusting the components in the material,the morphology,crystal structure and electronic structure of the nanocomposite can be controlled,and the synergistic effect between the components can be used to improve the material performance.Based on this,this paper aims to develop a template strategy to accurately synthesize various novel transition metal-based nanocomposites to improve or overcome the limitations of individual components in different application scenarios,give full play to the advantages of each component,and make its performance better than that of individual components,so as to meet the needs of different applications.The specific research content mainly includes the following three aspects.（1）The Yolk-Shell nanocomposite materials with hierarchical porous structure have a large specific surface area and can be widely used in the fields of catalysis,energy,and sustained drug release.In this study,a one-pot method/step reaction strategy was adopted to successfully prepare the Co-based ZIF-67@Co-LDH Yolk-Shell structure.The crystal of ZIF-67 rhombic dodecahedron was etched by metal cobalt ions to gradually form the hydrophilic shell layer with mesoporous structure of Co-LDH sheet.The unique structure,hydrophilic and hydrophobic properties can control the shuttle between the inside and outside of the guest species,which can not only improve the stability of ZIF-67,but maintain ZIF-67reactivity in humid environments.The sustained release effect of the Yolk-Shell structure was studied by loading Rhodamine 6G model drug molecules.The results showed that the ZIF-67@Co-LDH composite with hierarchical porous structure had higher loading capacity and longer sustained release time compared with ZIF-67 nanocrystalline and Co-LDH hollow cage.（2）Using the rich electronic structure of transition metals and the high conductivity of carbon nanotubes,we successfully constructed the composite structure of Mn-doped Ni-LDH nanocrystals loaded carbon nanotubes by the method of in-situ growth.On the one hand,the composite structure solves the problems of poor conductivity and stability of Ni-LDH material and easy agglomeration of nanosheets.On the other hand,the surface electronic structure of Ni-LDH is adjusted by Mn ion,thereby improving the electrocatalysis of Ni-LDH on CO₂RR performance.（3）Metal-supported porous carbon nanocomposites usually exhibit high performance in the field of electrocatalysis.In this study,we used preassembled copper complexes with different nuclei(Cu₂,Cu₂₄),which were loaded on MOFs-derived carbon materials,to accurately prepare different sizes of sub-nanometer copper cluster-supported porous carbon composite structures（Cu/C）.The nanocomposite showed excellent electrocatalytic performance for CO₂RR.What’s more interesting is that compared with large nanoclusters,with the decrease of copper cluster size,the CO₂reduction products gradually transform from CO to CH₃OH and CH₃CH₂OH.