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1D Core-Shell Nanostructures Formed By Electrodeposition of Metals and Metalloids in Anodic TiO2 Nanotubes

Wednesday, 4 October 2017: 12:00
Chesapeake H (Gaylord National Resort and Convention Center)

ABSTRACT WITHDRAWN

The anodizing is a high-voltage electrochemical conversion process that forms barrier-type or nanoporous/nanotubular oxides on valve metals and alloys, mainly depending on the composition of electrolyte used.[1] The key to achieve the ordered nanoporous/nanotubular structures is a displacement of the film material above the original surface position due to synergistic effect of pits generation (field assisted oxide dissolution), stress generated at the metal-oxide interface including electrostriction and plastic oxide flow switching the growth of the barrier-film to nanotube/nanopore. Typically, the TiO2nanotube array formed in organic electrolytes such as glycerol, dimethyl sulfoxide, ethylene-glycol is obtained in the form of close packed structure in which the nanotubes nearly stick together with the tube walls. A fundamentally different nanostructure from that is obtained in diethylene-glycol electrolyte. The nanostructure is characterized by free standing nanotubes separated by an interconnecting space much bigger than the thickness of nanotube wall. [2,3] Such geometry gives possibility for deposition of secondary materials using electrochemical processes in view of improved wetting behavior of the nanostructure. [4] Herein we report on how to control the electrodeposition process to achieve unique core-shell geometries. We discuss on wetting behavior and nucleation-growth on such porous structures, a key points to achieve controlled electrodeposition. An examples of composites formed between oxide layer and Si, CdSe, Au, Pt will be demonstrated.

References:

[1] D. Kowalski, D. Kim and P. Schmuki, Nano Today, 8(2013) 235.

[2] D. Kowalski, J. Mallet, J. Michel, and M. Molinari, J.Mater.Chem.A 3(2015) 6655.

[3] D. Kowalski, J. Mallet, S. Thomas, J. Rysz, B. Bercu, J. Michel and M. Molinari, Electrochim. Acta, 204(2016) 187.

[4] D. Kowalski, and P. Schmuki, Chem. Comm., 46(2010) 8585.

Fig. 1 Core-shell structures formed by means of electrodeposition of Si and Au. STEM image (left) shows 60nm thick silicon layer electrodeposited from ionic liquid electrolyte on the outer-shell of TiO2 nanotube. Back scattering electron image (right) shows gold electrodeposited in-between the bottoms of TiO2 nanotubes.