Synthesis And Organic Catalyzing Application Of Oxygen Deficient Nanomaterials

Oxygen vacancies,one of the most common point defects,influence the materials' surface properties,such as electron transport,geometry and electronic structure,the activity and selectivity of the catalyst,etc.Therefore,the detection of oxygen vacancies,the deep understanding of the effects of oxygen vacancies in materials from microscopic view,and the rational introduction of oxygen vacancies into metal oxides play a vital role in improving the performance of materials.This dissertation mainly focuses on the design,synthesis and catalytic performance of oxygen-deficient metal oxide materials.The details are as follows:In chapter 2,a simple hydrogen thermal reduction method was used to uniformly load Pd nanoparticles(NPs)on the oxygen deficient Pr6O11 support.XPS and EPR analysis confirmed the existence of oxygen vacancies in support,which can act as an electron donor to increase the electron density of the Pd NPs,and it is beneficial to the adsorption and activation of the reactants,thus,improving the catalytic efficiency.The hydrogenation of p-nitrophenol and styrene are used as model reactions to evaluate the catalytic efficiency.The results show highly efficient styrene hydrogenation performance under 1 atm H2 at room temperature with a TOF value as high as 8957.7 h-1,and the rate constant value of p-nitrophenol reduction is 0.0191 s-1.In addition,the catalyst can be recovered and reused for up to 10 consecutive cycles without marked loss of activity.In chapter 3,a general and one-step template-free chemical transformation strategy without using any surfactant was investigated to fabricate multifunctional mesoporous oxides.The transformed material had a specific surface area of up to 369 m2 g-1.Specifically,the original ZnSn(OH)6(ZSH)solid nanocube was selected as a starting material,and converted it into mesostructures with a large specific area of 369 m2 g-1.This chemical conversion process was achieved by one-step solvothermal treatment through ethanol due to thermal dehydroxylation of ZSH,which are known to be hard to synthesize directly.Besides,ethanol can serve as reducing agent and produce numerous oxygen vacancies on the surface of the samples,which is in favor of the enhancing of catalytic performance.Thus,the selective aerobic oxidation of benzylamine to N-(benzylidene)benzylamine was taken as model reaction to examine the photocatalytic activity and stability of the as-prepared catalysts.The results show highly efficient oxidation performance under 1 atm O2 at room temperature.Various amines derivates were also tested to verify its wide substrate adaptability.Moreover,this method is successfully applied to obtain other mesoporous ternary metal hydroxides,such as mesostructural CuSn(OH)6.