Highly Ordered ZnS Nanowire Arrays Embedded In Anodic Alumina Membrane By A Hydrothermal Method With Double Diffusion

With the development of nanotechnology since the1960s, nanomaterials are widelyused in various fields. In recent years, high density and well-ordered arrays ofnanowires are needed, as they are used in electric and optoelectronic devices such fieldemission displays and data storage.ZnS, as the typical II–VI semiconductor compound with bandgap energy of3.6eVat room temperature, has outstanding performance in optical properties andluminescence properties, for what ZnS is widely used in flat-panel displays,electroluminescent devices, infrared windows, sensors and lasers. So much attention hasbeen focused on the synthesis of ZnS nanowires or nanotubes which are highly ordered.As the traditional methods are uncontrollable, it’s difficult to get highly ordered Zn<nanowires. Here in this paper, we report a new way to fabricate the ordered ZnSnanowire arrays in AAO by hydrothermal with double diffusion.(1) Highly ordered ZnS nanowire arrays were successfully synthesized by thehydrothermal method with double diffusion with AAO template，which was confirmedby the results of XRD,SEM,EDS and TEM.(2) The results of the SEM indicate that the obtained nanowires were built withcrystalline ZnS grains, which contains a very developed free surface as well as grainboundaries with extremely high specific area. The diameter of the as-prepared ZnSnanowires was about80-100nm, which was well corresponded to the pore size of thetemplate we used.(3) Photocatalytic performances of the as-prepared ZnS nanowires were studied.The results indicated that our ZnS nanowires showed photocatalytic activity, however,the performances are not desirable as the total amount of the prepared sample is quite little.(4) Preliminary mechanism of this method to synthesize ZnS nanowires wasexplored. The diffusion velocities of Zinc source and sulfur source were different in thetemplate, therefore with short reaction time, different concentration ratio lead todifferent morphologies of ZnS nanowires. With a small Zn(Ac)2concentration, ZnSnanowires could be well grown on both sides of the AAO template even in a shortreaction time. While when it comes to Na2S2O3, there were only a little ZnS nanowiresformed on the other side of the template, and as time extended, nanowires grew on bothsides and gradually filled the holes. As the work of the heterogeneous nucleation is lessthan homogeneous nucleation, ZnS nanocrystal first nucleated on the wall of the AAOtemplate, then because the nucleation rate on the as-formed nanoparticles is higher thanthat on the AAO template, more crystal nucleated and grew on the as-formednanoparticles, and finally formed the dense nanowire structure accumulated by smallernanoparticles.