The Construction Of RuO₂-TiO₂ Mixed Oxide And Investigation On Reactivity Of Co Oxidation

The surface and interfacial catalysis plays important role in chemical industry,electrocatalysis and photocatalysis.Optimizing chemical processes and understanding reaction mechanism are critical challenges for modern catalysis.Since¹960s,the foundation of surface science systems has allowed the study of surface and interfacial phenomena on atomic/molecular level.Therefore,we have updated the STM system and calibrated the XPS system of surface analysis.Furthermore,standing on insight of surface science,we have studied the interfacial properties of RuO₂/TiO₂.These researches have built base work to further research catalytic process and is helpful to construct theory of interfacial interaction between mixed oxides.Firstly,this work updated STM and XPS system.Then we studied the structure of RuO₂/TiO₂ depended on crystalline phase of suports.By optimizing the calcined temperature,and using related characterization,the critical role of TiO₂ crystalline phase on dispersity of RuO₂ is revealed.By further XPS characterization,we have identified the critical Ru loading for high dispersity of RuO₂ on r-TiO₂.Based on the ordered interfacial structure between ulthin RuO₂ and TiO₂ surface,the thesis also investigates the relationship between kinetic of CO oxidation and interfacial electrons transfer between RuO₂ and TiO₂.By combing spectroscopic studies and density functional calculation,we have acquired that at very low loadings,the majority of RuO₂ catalysts can be anchored at the defective sites of TiO₂ substrates.The electron transfers from defective sites of substrates to RuO₂ causes an increase in the apparent reaction barrier of CO oxidation.As the loading of Ru increases,RuO₂starts to appear on the terrace of TiO₂,and the apparent reaction barrier of CO oxidation decreases.At the medium loading of⁰.75 wt%,the lowest apparent reaction barrier is achieved.The phenomenon can be attributed to the electron transfer from RuO₂ to the terrace of TiO₂.Further increasing the loading of Ru,the apparent reaction barrier rises again.When the loading of Ru is more than 2 wt%,the apparent reaction barrier is found to be very comparable to that over RuO₂ catalysts supported on inert substrate,indicating that the electronic effect of TiO₂ is isolated underneath thick RuO₂ overlayers.