Fabrication Of Multiple-scale Porous Anodic Aluminum Oxide Template And Its Application In Ni Replication

Multiple-scale structural materials are a kind of structure-functional integrated materials,which are composite structural materials.It is formed by combining the excellent properties of nanomaterials and the outstanding stability of micro-scale structures,having wide applications in various fields: bionics,catalysis,sensors.Ni nanomaterials have received extensive attention due to their excellent magnetic,catalysis properties.Porous Anodic Aluminum Oxide(AAO)is the most commonly used template for the fabrication of diverse nanomaterials because of its apparent advantages,such as adjustable parameters,reliable fabrication process,and low cost.In this paper,porous AAO membranes with micro/submicron/nano multiple-scale structure which can be used as the temples for preparing multiple-scale structural materials have been fabricated.Meanwhile,Ni nanoarrays synthesized by pulse electrochemical deposition based on ordered porous AAO templates have been explored.(1)Porous AAO membranes with micro/submicron structures have been fabricated by using high anodization voltage(400~600 V)in oxalic acid electrolyte system(0.3 M oxalic acid: ethanol = 1:1,V/V).The effects of voltage and electrolyte temperature on the growth process of porous AAO membranes and the morphology of barrier layer have been investigated.(2)Porous AAO membranes with micro/submicron/nano multiple-scale structure were prepared at low anodization voltage(40 V)in 0.3 M oxalic acid electrolyte based on the first high voltage anodized aluminum substrate.The impacts of different first anodization voltages on the current density of the second anodization have been studied.(3)Crystallized porous AAO membranes were fabricated at ultra-high anodization voltage(700~1000 V)in the oxalic acid electrolyte system(0.3 M oxalic acid: ethanol = 1:2,1:3,V/V).The influences of ethanol content in the electrolyte on the anodization process as well as the anodization voltage/current density-time transient were analyzed in details.The morphology of porous AAO membrane indicated the formation of crystallized alumina,further confirmed by X-ray diffraction(XRD).The crystallization process of alumina was discussed,and the structural model of polycrystalline porous AAO membranes was proposed.(4)Porous AAO templates with Au,Al,ZnO electrode were produced by various methods.The fabrication process of self-supported porous AAO template with Al electrode and the characteristic of different methods have been discussed.(5)Ni nanoarrays have been fabricated by pulse electrochemical deposition on porous AAO templates with different electrode.Ni nanowires,Ni nanopillars/nanowires with supporting structure,and Ni filled ZnO nanotubes were prepared by porous AAO templates with Au,Al,ZnO electrode,respectively.The redox reaction of Al in the electrolyte and the electrochemical deposition process have been investigated.