Controllable Synthesis And Catalytic Study Of Platinum- And Ruthenium-Based Nanocrystals

Noble metal nanocrystals(NMNCs)are important catalysts that have been receiving great attention in the fields of fuel cell,petrochemical industry,and several others.Developing low coat and high performance catalyst has become an urgent scientific problem.Recent studies have shown that the catalytic performance of NMNCs is strongly dependent on their composition,size and surface structure.Accordingly,a rational design of NMNCs structure at nanoscale and developing efficient NMNCs synthesis are effective ways to enhance the catalytic performance of NMNCs.In this dissertation,we focused on the controllable synthesis of Pt-and Ru-based nanostructures,and the study of their electrocatalysis and hydrogenation reactions applications,with the aim to reveal the structure-performance relationship and develop more efficient catalysts.Fabrication and catalytic performance of bimetallic NPs with surface defects.The surface defects of nanocrystals(NCs)usually promote chemical reactions.Here,we successfully fabricated Pt-Cu bimetallic NCs with different degrees of stacking,and Pt-Fe bimetallic NCs with different degrees of carving.The aberration-corrected HRTEM showed that there are lots of defect sites on the junction area of Pt-Cu NCs and erosion area of Pt-Fe NCs,respectively.The methanol oxidation and oxygen reduction current density of multimeric octahedral Pt-Cu NCs are 8 and 11 times that of commercial Pt/C catalyst,respectively.Furthermore,the high electrocatalytic performance could also be found in the Pt-Fe nanodendrites.The method demonstrated here might be another effective way to rational design of fuel cell catalysts with excellent properties.Controllable synthesis and catalysis using multi-metallic NCs.The precisely controllable synthesis of multi-metallic NCs still remains great challenges because of the complicated compositions and different reduction potential of these NCs.We systemically investigated the formation process of Pt-PdCu multi-metallic NCs,and developed a facile “etching-reduction-selective epitaxial growth synergistic”(ERSS)strategy.Similar multimetallic NCs with novel heterostructures could also be effectively fabricated via the ERSS strategy.Preliminary electrochemical studies have confirmed the superior and stable catalytic performance of as-prepared Pt-Pd-Cu trimetallic NCs.Moreover,we synthesized a series of Pt-Mo-M(M = Fe?Co?Mn?etc.)trimetallic nanowires with high ratio of surface atoms.These Pt-Mo-M NCs have highly promising catalytic applications owing to their enriched steps,kinks and defects.Controllable synthesis and catalysis of Ruthenium-based NCs.We develop one-pot strategy to synthesize capped-column Co@Ru nanostructures.We found that the formation of Co@Ru nanostructure evolves from “axial growth” to “radial growth”,as well as the composition change from “Co-rich” to “Ru-rich”.These Co@Ru nanostructures have shown composition-dependent catalytic activity and selectivity toward hydrogenation reactions.In addition,the strategy developed here could also be extended to the synthesis of other Ru-based nanostructures.