Preparation of nanoporous alumina hollow spheres with a highly ordered hole arrangement.

Takashi Yanagishita,Masahiko Imaizumi,Hideki Masuda,Toshiaki Kondo

doi:10.1039/c7ra12340j

Takashi Yanagishita, Masahiko Imaizumi + Show 2 more

Open Access

https://doi.org/10.1039/c7ra12340j

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Abstract

Nanoporous alumina spheres with an ordered hole arrangement were prepared through a two-step anodization of small Al particles. The hole periodicity in the ordered anodic porous alumina could be controlled by adjusting the anodizing conditions. Nanoporous hollow spheres were also obtained by removal of residual Al in an etchant. Additionally, nanoporous spheres loaded with Au nanoparticles on their surfaces were obtained through electrochemical or chemical deposition of Au nanoparticles. The obtained Au/alumina composite hollow spheres were used as a substrate for surface-enhanced Raman scattering measurements.

Highlights

There has been increasing interest in nanoporous particles and hollow spheres because of their potential application in several types of functional devices, such as catalysts, sensors, and drug carriers.[1,2,3,4,5,6,7,8,9] To optimize the properties of nanoporous particles towards speci c applications, control of the porous structure at the surface of the particles is essential
We describe the preparation of nanoporous particles and hollow spheres with a highly ordered hole arrangement
Nanoporous spheres with a hexagonally arranged array of uniform-sized holes on their surface were prepared by two-step anodization of small Al particles

Summary

Introduction

There has been increasing interest in nanoporous particles and hollow spheres because of their potential application in several types of functional devices, such as catalysts, sensors, and drug carriers.[1,2,3,4,5,6,7,8,9] To optimize the properties of nanoporous particles towards speci c applications, control of the porous structure at the surface of the particles is essential. The two-step anodization process reported previously was adopted to prepare ordered anodic porous alumina on the surface of the Al particles.[22] In this process, a rst long period of anodization and subsequent removal of the oxide layer formed in the rst period of anodization generated ordered concave arrays on the surface of the Al substrate. For the preparation of the Au/alumina composite hollow spheres, the residual Al in the anodized Al particles was dissolved by immersing the particles in a saturated iodine methanol solution at 50 C for 12 h. In this process, the contacting portions of the Al particles were not anodized because it was difficult for the electrolyte to penetrate into these areas. SERS measurements were carried out using Raman spectroscopic apparatus (JASCO NRS-2000), using an He–Ne laser for excitation

Results and discussion

Conclusion

Conflicts of interest