Design Synthesis,structure Regulation And Catalytic Properties Of Several Supported Noble Metal Nanomaterials

Catalytic reactions play an important role in industrial chemical transformations.The increasing energy crisis and environmental problems prompte scientists to develop more efficient catalyst systems in various fields.Nano-catalysts showed excellent catalytic performance due to their small particle size,high specific surface area,and abundant unsaturated surface atoms and attracted much attention.In-depth insight into the relationship between the fine structure and catalytic performance of nano-catalysts is crucial to the innovation of catalysts.In recent years,although nanotechnology has triggered great progress in catalyst synthesis and characterization,there is still a lack of function-oriented synthesis methods for nano-materials,characterization of fine structure at atomic scale,and in situ analytical methods for understanding catalytic mechanisms.In this paper,focusing on the most commonly used selective hydrogenation/oxidation reactions in catalysis,we have constructed a variety of advanced composite nano-materials by tailoring the composition and structure,developed a variety of surface state fine-regulation methods,and realized a great improvement in catalytic performance.On this basis,we established a typical structure-activity relationship model with the help of in-situ spectroscopy technology and density functional theory analysis,and elaborated the synergistic mechanism among different components.The main results are as follows:1.We prepared porous Ir Co dodecahedrons composed of a large number of ultra-nanoparticles by a top-down synthetic route.This synthesis method can realize the complete alloying of Ir and Co atoms at extremely low calcination temperature（200℃）,which effectively broke the thermodynamic limitation of heterogeneous metallic alloying with large lattice differences.Benefiting from the special structure of Ir Co alloys,we constructed a light-driven,highly selective hydrogenation system using ammonia borane（AB）as the hydrogen source.The materials can completely convert 4-nitrostyrene（4-NS）within 15 min and show 97%selectivity for4-aminostyrene（4-AS）.Besides,the TOF reached 50.25 h^-1.Through theoretical research and experimental verification,we propose a light-driven hydrogen transfer reaction mechanism,and accurately describe the ultra-high catalytic performance of Ir Co alloys at the atomic scale.2.We synthesized Ag-Au NC@Ce O₂ core-shell structure by a simple self-assembly method and explored its catalytic performance in cascade reactions.The results showed that core-shell structure has both glucose oxidation activity and peroxidase-like activity.And it showed excellent activity in the glucose oxidation cascade reaction,which provided a new idea for the design of the cascade reaction catalysts.Moreover,on the basis of the optimal reaction p H,we explored the linear regression equation between absorbance and glucose concentration,which makes it possible to detect glucose without enzyme.3.We designed a clean synthetic route,ultra-small Pd O_x particles were deposited in situ on the S1,and prepared Pd@Ce O₂ core-shell-like structure（q-Pd@Ce O₂/S1）by auto-redox reactions between reduced Ce³⁺and oxidized Pd O_x in solution.Repeated calcination and aging experiments show that the core-shell nanostructure can effectively prevent the internal Pd core from agglomerating.When used as a quinoline hydrogenation catalyst,q-Pd@Ce O₂/S1 can achieve 100%conversion within 12 h,and the 1,2,3,4-tetrahydroquinoline（py-THQ）selectivity is as high as 99%.4.We prepared Mo₂N supported Pt single atom by developing a high-temperature reversing sintering process and achieved excellent reverse water gas shift reaction performance in CO₂ hydrogenation.The CO formation rate of pre-prepared catalysts reached 257 mmol g^-1_cath^-1,which was 1.6 times that of pure Mo₂N,and the selectivity of CO kept above 93%.Besides,benefiting from the interaction between Pt atoms and Mo₂N support,in situ characterization and theoretical studies showed that the doping of Pt atoms changed the free energy of O species binding to H₂ in the rate determining reaction step,accelerated the redox cycle on the surface of Mo₂N and promoted the rapid conversion of CO₂ molecule.