Structural Design,Synthesis And Tuning Properties Of Platinum Based Photothermal,Catalysis Nanomaterials

Platinum has the outermost electron configuration of 5d94s1.With unfilled d sublevel,the reactants are preferentially absorbed on the surface of platinum at moderate coordination strength,which is in favor of the formation of active intermediate compounds,thus leading to high catalytic activity,accompanied with good heat resistance,anti-oxidation,corrosion resistance and other comprehensive properties.These advances make platinum becoming the most important catalysis material.Platinum is also a plasmon metal,with high-order longitudinal SPR mode in near infrared zone.Owing to the electron-phonon scattering,platinum has relative strong photothermal effect.Structural design could tune the exposed facets,adsorption properties,spatial selectivity,electronic structure,thus affecting the performance of catalysis,photothermal and so on.Such strategy has been verified by thousands of researches.Under the attractive demands of reducing the usage of platinum in the catalytic industry,improving the stability,activity and selectivity of catalytic materials,and expanding the applications in sensing,devices,biotherapeutics and so on,still a lot of researches urgently need to be studied on tuning the properties of Pt-based nanomaterials through structural design.In this thesis,we carried out the structural design,synthesis and tuning properties of new type Pt-based superstructure nanocrystals for photothermal and catalysis application.In addition,we systematically characterized the materials accompanied with the simulation,then analyzed the structure-effect relationship in the load,cladding and superstructure of platinum-based nanomaterials towards hydrogenation reaction,absorption,photothermal and biocatalysis properties.Adopting OTAB-Na as surfactant and ascorbate acid as reducing agent,Pd@Pt bimetallic nanocrystals with complicated shape are synthesized by using one-pot two-step strategy under mild reaction condition in aqueous phase,despite the distinct characteristics of palladium and platinum.This synthesis procedure could also be extended to Au@Pt.By the component adjustment and the shape design of core@superstructured-shell,the apparent spiral shell consisting of platinum nanowires tightly wraps around the palladium core,enhances the transmission capacity of the substrate and optimizes the catalytic properties of palladium and platinum.The catalyst has significantly enhanced catalytic activities in the nitrobenzene hydrogenation reaction,which solves the crucial problem that the properties in single component materials is difficult to regulate.The photothermal properties of Pt materials are enhanced by sifting up the potential in the single component material.Based on the strong plasmon effect and surface-enhanced Raman scattering in the superstructured platinum nanocrystals,we could regulate the absorption and manipulated photons to induce the electric field and then enhance catalytic activity and photothermal conversion by structural design.Using a simple acid etching procedure,the Pd cores in Pd@Pt are selectively removed,with the spiral shell-structure maintained.Such Pt Spirals hollow superstructures nanoparticles with single component and multi-level structure,take into account the demands of photothermal therapy for near-infrared molar extinction efficiency and photothermal conversion efficiency,the tumor ablation effect of which is verified in vivo.Meanwhile,we proposed and verified the energy transfer approach that photons are absorbed by plasmon nanoparticles and induce enhanced electric fields.Then free electrons in metal structures excite into hot electrons and effectively separate from the holes,dissipating the energy to heat through non-radiation.The results show the essence of superstructure in dominating the photothermal conversion efficiency and the feasibility of structural design in regulating the properties of nanoparticles.