Research On The Preparation And Catalytic Performance Of Hollow Precious Metal Nanostructures

Manipulating the morphology and size of noble metal nanostructures(NMNSs)is an effective strategy for improving their utilization and catalytic performance.Recently,hollow and porous NMNSs,which are emphasized as noble metal nanomaterials with a large fraction of empty space inside,are attracting more attention due to their unordinary structural features,including the large specific surface area,interconnected structure,ample defect atoms in edges and corners,permanent porosity,fast mass transfer,and less Ostwald ripening.Consequently,hollow and porous NMNSs have been applied widely in heterogeneous catalysis,which generally display improved catalytic activity,durability,and structural stability.At present,the hard templating synthesis,soft templating synthesis,and self-templating synthesis are three main strategies for the preparation of hollow NMNSs.Among them,the hard templating synthesis is a most widely used method due to the diversity and universality of hard template materials.In this thesis,we have prepared several hollow noble metal nanomaterials and explored their applications in environmental governance and fuel cells.The main results are as follows:1.One-pot fabrication of hollow and porous PdCu alloy nanospheres(PdCu HPANSs)and their remarkably improved catalytic performance for CrVI reduction.In this work,we developed a facile one-pot synthesis of hollow and porous PdCu HPANSs in the presence of polyethyleneimine(PEI).During the synthesis,PEI played a key role in the formation of Cu2O template and succedent removal of Cu2O cores under very mild conditions(in air and at room temperature).When used as a catalyst for the reductive transformation of CrvI to Cr? by HCOOH,the as-prepared PdCu HPANSs displayed remarkably enhanced catalytic performance compared to commercial Pd black at room temperature.2.PtAg alloy nanoballoon nanoassemblies(PtAg ANBNSs)with super catalytic activity for the formate electrooxidation.In this work,hollow and porous PtAg ANBNSs were synthesized by the galvanic reaction between K2PtC14 and three-dimensionally(3D)multibranched Ag nanoflowers template.Due to the geometric/electronic effects and porous architecture,PtAg ANBNSs exhibit a 19.3-fold activity enhancement for the formate oxidation reaction(FOR)compared to commercial Pt nanoparticles in KOH solution.In addition,the preferential dehydrogenation pathway of the FOR,good anti-CO poisoning capability,and 3D self-supported structures of the PtAg ANBNSs result in excellent electrocatalytic stability for the FOR in alkaline media.3.Porous trimetallic PtRhCu cubic nanoboxes(PtRhCu CNBs)for the ethanol electrooxidation.In this work,we designed and synthesized PtRhCu CNBs by the galvanic reaction between K2PtCl4,RhCl3 and Cu2O nanocubes template.The shell thickness and chemical composition of PtRhCu CNBs can be easily regulated by controlling the amount and proportion of noble metal precursors.Due to geometric effect and alloy effect,the optimized PtRhCu CNBs exhibit super eletrocatalytic activity for the ethanol oxidation reaction.