Influence Of Metal-Oxide Interface Regulation On The Thermal Stability Of Nano-Au

Noble metal nanoparticle catalysts have been widely used in industrial catalysis,whose activity largely depends on their particle size.Specifically,reducing particle size is also beneficial to expose more active sites,and thus improve the atomic economy.Many catalytic reactions require triggered under the condition of relatively high temperature accompanied by exothermic phenomena,resulting in the agglomeration and deactivation of metal nanoparticles.Improving the thermal stability of the catalyst is crucial to improve its longevity and thus reduce the cost,which plays an important role in promoting its practical application.Studying the factors that affect the growth and deactivation of the catalyst has important theoretical value and practical significance for the design of nanoparticle precious metal catalysts with higher activity and longer life.In this essay,the nano-Au was selected as the model material,the inhibition of Au NPs sintering by the support structure of the catalyst was studied under the premise of controlling the particle size,uniform distribution and uniform sintering atmosphere of Au nanoparticles.The results of the research obtained are as follows:1.The TiO2 film was prepared on the surface of Ti film as the carriers of Au,and the surface morphology was TiO2 nanotubes with different length.The Au nanoparticles were uniformly supported on the surface of the support by ion sputtering to obtain a metal-based sample.The TiO2 film on the surface of the Ti piece was peeled off obtaining the oxide supported Au sample.2.Both samples with and without the metal substrate were calcined under the same inert atmosphere to observe the changes of Au particles kept at different temperatures.The results show that the Au-particles existing in the metal-based composite sintered more slowly at high temperature,and the activity was higher under the reaction atmosphere while they still remain stable at high temperature.It was verified by experiments that oxygen vacancy concentration of the materials increased due to the addition of metal Ti.DFT has verified that the nonquantitative TiO2 support can stabilize the small Au clusters and make them exbibit the trend of growing into the particles with relative small size,which can improve the thermal stability of catalysts.3.Both TiO2 and CeO2 complex hollow spheres have been designed as supports using TiO2 and carbon microspheres as templates,respectively.The diameter of TiO2 spheres was as large as about 700?800 nm,and the ball wall was relatively thick.However,for carbon spheres,it was only about 100?200 nm,and the ball wall was so thin that the Au particles could be halfinlaid between those two ball walls.The deposition-precipitation method was used to prepare Au particles with uniform particle size.The active site could be exposed while Au NPs were in contact with those two oxides.4.Dioxides supported catalysts with spherical shell structure prepared via carbon sphere templates exhibited higher catalytic activity than the catalysts prepared by TiO2 spheres in CO catalytic oxidation reaction.It displayed excellent thermal stability in the cycle test and high temperature reaction.The catalyst could remain its high activity after high temperature tests.The double oxides were in close contact with the Au particles,whose interaction made Au nanoparticles anchored more stably in the reaction.