Synthesis And Material Properties Of AuAg/CdS Double-wall Nanotubes

With the development of nanoscale science and technology,noble metal and semiconductor nanomaterials have drawn much attention on the synthesis and properties.Since both the noble metal nanomaterials and the semiconductor nanostructures are of excellent optical and electrical properties,the composites of them are more interesting.The surface Plasmon of the noble metal nanomaterials and the exciton of the semiconductor nanostructures interact,then lead to the changes on the optical and electrical properties of the composites.Although there have been diverse metal/semiconductor composite structures,how to achieve the maximum interface and provide the most suitable Plasmon-exciton interaction platform still remains a problem.Above all,this thesis focused on the synthesis and optical/electrical properties of the novel structure-AuAg/CdS double-wall nanotubesIn this thesis,firstly Ag nanowires were fabricated as the original templates via the polyol process.Second,curtain amount of the HAuC14 solution were added into the Ag nanowires to synthsize AuAg alloyed nanotubes through the Galvanic replacement reaction.Then an Ag2S layer was further coated on the surface of AuAg alloyed nanotubes as a transition layer.Finally,taking the advantage of cation exchange method,the AuAg/CdS double-wall nanotubes were successfully synthesized.The nonlinear absorption(NLA)properties of the AuAg/CdS double-wall nanotubes were investigated with different excitation intensity through Z-scan method.The results showed that AuAg alloyed nanotubes exhibited intensity-dependent NLA properties and the pure CdS nanotubes exhibited reversed saturated absorption properties,while the AuAg/CdS presented saturated absorption properties.The unique NLA property of the AuAg/CdS is believed to be caused by the plasmon-exciton interaction in the metal-semiconductor double-wall structure.Due to the rapid increase in energy consumption,the great contradiction of energy consumption and supply breaks out,thus it is of great urgency to develop clean and reliable energy.Fuel cells and metal-air batteries relaying on oxygen reduction reaction(ORR),have emerged great potential.In this thesis,we designed novel metal alloy/transition metal sulfide ORR catalyst-AuAg/CdS double-wall nanotubes.From cyclic voltammetry(CV),rotating disk electrode(RDE)and durability test in 0.1 M KOH electrolyte at room temperature,it was found that the metal alloy layer inside leads to a significant change of the ORR performance,relative to pure CdS nanotubes.At last,the I-V properties of a single AuAg/CdS double-wall nanotube under variable temperature as 4-300K were studied.The I-V curves of AuAg/CdS under lower temperature are nonlinear,while in higher temperature region the curves are linear.We tried to use the thermal variable temperature activation model to analyze the physical mechanism of the resistance curve.