Synthesis And Optical Applications Of Core-Shell Structured Inorganic Nanomaterials

In recent years,nanomaterials have attracted much attention due to their rapid development in frontier fields such as catalysis,optics,electronics,and biomedicine.With the development of synthetic strategies and material characterization techniques,the properties of nanomaterials have been intensively investigated.The preparation of highquality nanomaterials has become the focus of attention.Core-shell structure nanomaterials have been widely concerned and studied due to their excellent properties.The existence of the shell materials can improve the properties of the original nanoparticles,such as improving the stability and dispersibility of the nanoparticles,improving the optoelectronic properties of semiconductor materials,affecting the growth of the core nanoparticles,enhancing the catalytic activity,and so on.Although a series of core-shell nanostructures have been successfully prepared,most of the existing studies rely on the research experience that are of poor repeatability.Therefore,it is particularly important to study the formation mechanism of core-shell structure and the mechanism of action of shell materials.This paper summarizes the controllable preparation of coreshell nanocrystals,discusses the influence of shell materials on the optical properties,stability,growth mode,and explores the applications of core-shell nanostructures information storage and photothermal therapy.The main research contents of this paper are as follows:1.CsPbX-₃@PbSO₄ core-shell nanocrystals were prepared by constructing PbSO₄ shell layer on the surface of CsPbX-₃ to improve the optical properties and stability of CsPbX-₃ nanocrystals.Compared to pristine CsPbX-₃ nanocrystals,the as-prepared CsPbX-₃@PbSO₄ nanocrystals exhibit significant enhancement in the optical properties.Benefiting from the efficient protection of inert PbSO₄ nanoshell,the obtained CsPbX-₃@PbSO₄ core-shell nanocrystals demonstrate great stability against light irradiation and polar solvents,including ethanol and acetone.Furthermore,anionexchange reaction is strongly restricted upon the encapsulation of PbSO₄ shell.2.Through the high temperature sintering strategy,the NH4AlP2O7 shell was successfully introduced to encapsulate the CsPbX-₃ nanocrystal,which greatly improved the stability of CsPbX-₃.Theoretical calculations prove that P2O74-is bound to Pb atoms on the surface of CsPbBr3 through Pb-O bonds.The as-obtained core-shell CsPbBr3@NH4AlP2O7 NCs exhibit impressive stability against water and maintain the initial optical properties with negligible change in 400 days.Furthermore,significant improvement of irradiation/thermal resistance has been realized due to the protecting role of pyrophosphate.The nanocrystals can retain 100%and ca.90%of the original PL after hundreds of heating/cooling cycles and several hundred hours of UV light irradiation,respectively.As a result,the core-shell products can be directly used for high-resolution inkjet-printing,enabling the printed fluorescent information to be resistant under harsh environmental conditions.3.The phenolic resin（RF）shell layer was used as the confinement space for the growth of gold particles to explore the effect of substance diffusion on the growth of the confinement space.Adjusting the cross-linking degree of RF can precisely control the transmission rate of Au monomer in confined space.As the transmission rate slows down,the self-nucleation phenomenon becomes more obvious in the confined space.We designed RF shell as a surface stress regulator（oxalic acid）buffer pool to regulate the surface stress of gold seeds to prepare gold superparticles with high photothermal conversion in the near-infrared region.4.A strain modulation strategy was proposed to produce branched Au nanostructures by promoting the growth of Au on Au seeds in the Volmer-Weber（island）mode instead of the typical Frank-van der Merwe（layer-by-layer）mode.The key of this strategy is to continuously deposit polydopamine formed in situ on the growing surface of the seeds to increase the chemical potential of subsequent deposition of Au,thus achieving continuous heterogeneous nucleation and growth.The branched Au superparticles exhibit a broad spectral absorption and photothermal conversion efficiency of 91.0%.Their superior photothermal efficiency allows us to further demonstrate the efficacy of these branched Au superparticles in cancer therapy and reveal their detailed biomolecular mechanism by proteomic analysis.