Preparation,Alloying Treatment And Catalytic Properties Of Au/PdPt Core/shell Nanowires

Recently,noble metal nanomaterials,owing to their unique physical and chemical properties,have been widely used in the fields of catalysis,sensing,energy source,etc.Abundant evidence indicates that the catalytic performance of noble metal nanomaterials is closely linked with their morphology,structure and composition:?i?nanowires exhibit much better durability than sphere-like nanoparticles;?ii?multi-metallic nanomaterials show much better catalytic activity than monometallic ones.To date,the catalytic property of sphere-like nanoparticles has been widely investigated because of its easy preparation.Nevertheless,only a few reports dealt with multi-metallic nanowires because of the difficulty of simultaneously controlling the reduction of multiple metallic ions and manipulating the growth direction.The difficulty to prepare multi-metallic nanowire severely restricts the people's understanding of its properties.On the basis of that,we investigated the controllable synthesis and the catalytic performance of Au/PdPt core/shell nanowires and AuPdPt alloy nanowires with different morphological structures.?1?Porous Au/PdPt core/shell nanowires were generated from Au/Pd core/shell nanowires via a galvanic replacement strategy,and controllable Pd:Pt atomic ratio and PdPt nanostructure can be achieved upon reaction time.According to the characterization of Transmission electron microscopy?TEM?,element mapping and X-ray diffraction?XRD?,the formation mechanism of porous Au/PdPt core/shell nanowires based on the synergy of galvanic replacement and chemical reduction was proposed.?2?The catalytic performance of as-prepared Au/PdPt nanowires was further evaluated by using methanol and ethanol electrooxidation,and Suzuke coupling reaction as model reactions.The catalytic performance of Au/PdPt nanowires depends on the Pd:Pt atomic ratio and PdPt nanostructure.Among all samples,Au/Pd₆₃Pt₃₇nanowires with the Pd:Pt atomic ratio of 63:37 exhibit the best electrocatalytic activity and durability towards methanol(⁴0.2 mA?cm^-2)and ethanol(³7.5 mA?cm^-2)electrooxidation,¹8 and 11 times the activity of commercial Pt/C.Also,Au/Pd₆₃Pt₃₇nanowires show excellent catalytic performance in Suzuki coupling reaction,⁹6%at yield,far better than commercial Pd/C catalysts.?3?AuPdPt alloy nanowires encapsulated by N-doped carbon layer?AuPdPt/C-N?was fabricated by annealing poly?aniline?-covered Au/Pd₆₃Pt₃₇7 nanowires at high temperature involving the polymerization of aniline around the surface of Au/Pd₆₃Pt₃₇.As-prepared AuPdPt/C-N was further characterized by TEM,XRD,X-ray Photoelectron Spectroscopy?XPS?,element mapping,etc.The optimized AuPdPt/C-N nanowires show the similar catalytic activity toward ethanol electrooxidation to Au/Pd₆₃Pt₃₇,but AuPdPt/C-N exhibits far better durability than Au/Pd₆₃Pt₃₇:after 5 h continuous electrooxidation,the remained activity of AuPdPt/C-N was still⁷5 times better that of Au/Pd₆₃Pt₃₇.