Forming Ceria Shell On Au-Core By LSPR Photothermal Induced Interface Reaction Used For Catalytic Reactions

In recent years, the core-shell structure of nano materials have been attracted much attention for their applications in heterogeneous catalysis. Due to synergy between core-shell components, so that it will have some new properties;the metal@oxide nanocomposite favors the interaction enhancement between the metal core and the oxide shell as well as improves anti-sintering ability of the metal particles, both of which are very valuable for metal/oxide catalysts. Core-shell nanometal oxides is a kind of new material, during the preparation, the key issues is whether "shell" or its precursor reactions localized on on the surface/interface of metal nanoparticles.In this thesis, a novel method for preparing core shell structure of Au@ceria was presented maked use of the Au nanoparticles?NPs? LSPR. The localized surface plasmon resonance?LSPR? is the result of the interaction between plasmonic metal NPs and the light with resonant frequency, LSPR can convert the energy of the light into heat, and the heat can trigger the shell formation reactions confined on the surface of the Au NPs. In short of the preparation procedure, aqueous sol of Au NPs, citric acid, ethylene glycol and cerous nitrate were irradiated with a Xe arc lamp, maintaining the temperature of the sol at 25 °C by cooling and stirring the sol. After different irradiation time, the heat from LSPR induced polymerization reaction in the sol, resulting in cerium gel formation which enveloped each of the Au NPs. Through the subsequent process, then will get a series of Au@CeO₂ core-shell structure.We conducted the structure of Au@CeO₂ precursor solution with transmission electron microscopy?TEM?, UV-visible spectroscopy?UV-vis? analysis, and explored different irradiation time effect on shell thickness. The result showed that with the increase of irradiation time, shell thickness is gradually increased, and the thickness reaches the maximum after 2 h, and no longer increase, at the same time, it also proved that different reaction time can control the thickness of the shell. Then we prepare Au@CeO₂ precursor composites with the average sizes of Au NPs, and also found different sizes of Au NPs coating CeO₂ precursor with different shell thickness.Finally in order to evaluate the catalytic properties of the Au@CeO₂ core-shell, the different carriers were been choosen to support Au@GCEC by impregnation method, then dried and calcined to obtain core-shell catalysts. And CO oxidation, photocatalytic water-splitting are used as probe reaction, they all exhibited good catalytic properties.