[CCoE Notice] Colloquium Announcement * April 9, 2010 * Nikolay Dimitrov * Department of Chemistry, SUNY at Binghamton

[Lewis, Lindsay R]

***** Colloquium *****

Center for Integrated Bio and Nano Systems

Houston Chapter of IEEE Nanotechnology Council and Houston Chapter of
IEEE Magnetics Society

Friday, April 9, 2010

12:30 p.m. (Refreshments served at noon)

Room: W122 Building D3

 

Nanoporous Metal Substrates: Electrochemical Processing and Surface Area
Measurements

 

Nikolay Dimitrov

Department of Chemistry, SUNY at Binghamton

 

 The electrochemical processing of nanoporous metals has been a booming
research field since the beginning of this century when a paper by J.
Erlebacher et al. published in Nature, 2001 made available to a wide
scientific audience understanding and skills associated with the
fundamentals of de-alloying. Many different systems including ideally
miscible alloys like Ag-Au, alloy systems with limited miscibility like
brasses and even phase separated metal mixtures like Ag-Ni have been
subjected to various de-alloying protocols all aimed at developing of
nanoporous and high surface area metal sponges consisting predominantly
of the remaining after the selective dissolution more noble alloy
constituent. Great deal of the remarkable research interest in the field
of de-alloying could be attributed to the wide variety of applications
of the accordingly processed nanoporous metallic materials. Specific
examples here could be filtration membranes, surface coatings with
controlled roughness and controlled pore-size architectures that could
accommodate either catalytically active enzymes or metal nanoparticles
specific functionality. More recently nanoporous metallic structures
have been eyed as potential thermal interface materials.

 

This talk is aimed at laying out the fundamentals of nanoporous
materials processing. De-alloying of single phase alloys and potential
controlled displacement are chosen to illustrate the similarity of final
products resulting from application of completely different experimental
approaches. The proposed presentation begins with introduction to
de-alloying fundamentals presented in view of experimental results and
modeling approaches. The concept of "critical potential" in the
selective metal dissolution is emphasized in this part. Arguments about
the influence of a pre-existing length-scale on the critical potential
in systems subjected to de-alloying are also considered. The
presentation continues with an introduction to the recently developed
method of potential controlled displacement that enables synthesis of
nanoporous materials in phase separated alloy systems where the standard
de-alloying methodology is virtually inapplicable.  Here, a detailed
analysis is proposed of the ratio of dissolution to deposition current
and its impact on the length-scale of accordingly grown nanoporous
material.  The talk wraps up with an introduction to the development of
an in-situ method for surface area measurements called "Electrochemical
BET" and its validation illustrated by a variety of means for tailoring
of the porosity length-scale and surface area, respectively. Arguments
are provided for interpretation of the impact of alloy composition,
original structure, processing parameters and thermal treatments on the
resulting porosity length-scale.  Conclusions and ideas for future work
encompass the current situation and lay out the most immediate
challenges in this field of research.   

 

Bio of Prof. Dimitrov:

 

Nikolay Dimitrov received his Ph.D. degree from Bulgarian Academy of
Sciences, Sofia, Bulgaria in 1993.  He was postdoctoral researcher at
Arizona State University (ASU) 1993-2000 and research
assistant/associate professor from 2000-2003.  In 2003 Dr. Dimitrov has
joined the faculty of the Department of Chemistry at SUNY - Binghamton,
Binghamton, NY where he is presently an Associate Professor. In 2008,
Dr. Dimitrov has been awarded NSF career award.

 

 

Contact Prof. Stanko Brankovic (stanko.brankovic at mail.uh.edu) if you
would like to arrange for a time to meet with Prof. Dimitrov.

 

 

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