Controllable Preparation Of Au@SnO₂ Core-Shell Plasmonic Materials And Its Photocatalytic Performance

With the advancement of science and technology and the improvement of quality of life,ever-incrementing industrial and agricultural production activities have produced more and more harmful environmental pollutants which are discharged into the aquatic environment,causing worldwide environmental and health Of serious concern.Photocatalysis technology is an effective and sustainable method of environmental remediation,which can photocatalytically degrade toxic and refractory pollutants into mineralized small molecules under mild environmental conditions,such as CO₂,H₂O,halogen ions,etc.However,traditional widely used photocatalysts?TiO₂,ZnO?can only absorb 5%of solar radiation in ultraviolet range.How to extend the spectral range of light absorption to visible?⁴2%sunlight?and infrared light?⁵3%sunlight?range,chemically modify wide band gap semiconductors,and finely design the electronic energy band structure of the photocatalyst to optimize light collection and charge separation,have become an important scientific issue.Recently,plasmon materials have received extensive attention due to their unique plasmon resonance characteristics and strong visible light absorption capability.However,the lifetime of hot carriers generated by metal plasmons is too short,and most of them are consumed in the form of heat radiation.How to construct a suitable plasmon structure,optimize the photoelectric separation scheme,and analyze various influencing factors in the process of photocatalytic degradation will be very important for photocatalytic degradation of environmental pollutants.In this thesis,we constructed tunable plasma resonance Au@SnO₂ core-shell structures,matched the energy band structure,optimized the photoelectric separation scheme,and pursued efficient visible light catalytic degradation of various environmental pollutants.The research contents of this thesis mainly include the following aspects:?1?We prepared Au nanospheres and Au nanorods in various sizes and length-to-diameter ratios by the seed growth method,and then assembled a layer of SnO₂ nanoparticles on the surfaces of Au nanospheres and nanorods by hydrothermal method,respectively.The composition and structure of the samples were characterized in detail by means of XRD,TEM,SEM,UV-Vis absorption spectroscopy and XPS.By adjusting the size of Au core,shell thickness of SnO₂,shell density,materials morphology,and other factors on the plasmon resonance absorption and energy band structure,to optimize the synthesis and growth process conditions and achieve a controlled synthesis strategy.?2?Using Au@SnO₂ spherical shell material to study the effect of plasmon resonance absorption shift?red-shift/blue-shift?on the performance of photocatalytic degradation of rhodamine B.Investigate the laser wavelength dependence and light intensity dependence on the photocatalytic performance.Analysis of the effects of various synthesis and growth factors?core size,shell thickness?on their photocatalytic degradation performance,and discussion of the photocatalytic kinetic behavior and calculation of quantum efficiency.?3?We investigated the photocatalytic performance of Au@SnO₂ rod shell material on degradation of tetracycline hydrochloride at different excitation wavelengths.the laser wavelength dependence and the light intensity dependence of the photocatalytic performance are discussed,by using illumination with different excitation wavelengths.In addition,the photocatalytic kinetic process is analyzed,and the photocatalytic mechanism is explained through free radical trapping experiments.