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Dr. J. T. Wolan
“Quick Glance” Project Info
Faculty/Industry Collaborators:
Dr. Stephen E. Saddow (USF
Electrical Engineering)
Current funding: Office of Naval
Research (ONR) and National
Science Foundation (NSF)
General Area/Focus: High power
SiC fuel cells
Application(s): A solid-state,
thin-film, SiC-based fuel cell, and
gas sensor, for use in harsh
environments
Project Title and Detailed Description
Project#1: “Novel All Solid-State SiC Fuel Cell for High Power Applications:
A Materials-By-Design Approach”
This research effort is focused on the integration of three critical components
toward the realization of a *solid-state thin-film SiC-based **fuel cell and gas
sensor for use in harsh environments. Our objective is to use novel porous Silicon
Carbide (PSC) materials to develop an all-solid state fuel cell that will more than
double the output power of Si-based fuel cells while completely eliminating the
problem of CO poisoning of expensive electrodes. In order to advance the current
fundamental knowledge base and realize this device, three areas of research must
be interwoven: ***heterogeneous catalysis, gas-sensitive electronic structures,
and novel fuel cell technologies. Although we have achieved promising result, a
deeper understanding of the fundamental interactions between energetic
gases/solid surfaces plays a key role in this application. There is little doubt that
microsystems will enable high-density power generation with an efficiency and
durability much exceeding current batteries.
Helpful Definitions:
*solid-state = crystalline materials with electronic properties
**fuel cell = device which utilizes a chemical reaction to produce an electric
current
***heterogeneous catalysis = a mixture of substances that speeds up a chemical
process
Faculty/Industry Collaborators:
Dr. Stephen E. Saddow (USF
Electrical Engineering), Prof. W.
J. Choyke Research Professor of
Physics, Department of Physics
and Astronomy, University of
Pittsburgh, Pittsburgh, PA
Current funding: Office of Naval
Research (ONR)
General Area/Focus: Solid-state
Hydrogen gas sensing
Application(s): Hydrogen gas
leak detection and sensing in
harsh environments
Faculty/Industry Collaborators:
Dr. Take Constantinesu R&D
director, Vandeputte
Oleochemicals
Current funding: ONR
General Area/Focus:
Heterogeneous catalysts for
Project#2: “SiC-Based Smart Hydrogen Sensor for Extreme Applications”
Effective hydrogen sensors and *ancillaries, to accurately and quickly respond to
hydrogen gas leaks, will be critical in the safe deployment of mobile, hydrogenbased vehicles and stationary hydrogen-derived power sources. Successful
hydrogen-leak detection will depend on the following factors: no false alarms;
integrated autonomous shutoff/venting procedures; **multiplexed sensor arrays;
and reliable sensing, calibration and self-testing. In other words, a smart, robust
device is needed. Our objective is to use novel porous Silicon Carbide (PSC)
materials to develop an all-solid-state gas sensor that can be used over a wide
range of extreme conditions and hydrogen concentrations, with minimal
interferences from other gases. The net result is a rather simple and inexpensive
gas sensing device that completely eliminates the need for transition metals and is
totally compatible with current IC processing techniques.
Helpful Definitions:
*ancillaries =
** multiplexed senor arrays = a grid of specialized sensors with different
functionalities.
Project #3 “ Partial Oxidation of Butane into Maleic Acid”
We are investigating the use of nanoporous SiC supported vanadium phosphorus
oxide (VPO) catalysts with proprietary promoters to be used in a fixed-bed micro
reactor. The reaction is very *exothermic and traditional ceramic-based supports
do not allow sufficient heat dissipation. This results in hot-spots in the catalytic
bed and destruction of the catalyst. The use of nanoporous SiC supports will: 1)
increase the surface area of the bed thus reducing the amount of catalyst needed
and speeding up the reaction, and 2) act as a very efficient heat sink. SiC
selective alkane oxidation
Application(s): Maleic acid is a
precursor to a large variety of
industrial products such as resins
for boats, autos, pipelines etc.
Faculty/Industry Collaborators:
Dr. Julie Harmon, Chemistry
Department, USF
Current funding: NSF
General Area/Focus:
nanocrystalline
SiC/polycarbonate composites
Application(s): For the
production of polymer composite
materials that: have low index of
refractions, are radiation hard,
exhibit increased strength and
resistance to fracture.
approaches heat transfer abilities as that of copper metal. In this way, heat
generated by the reaction can be removed quickly.
Helpful Definitions:
* exothermic = gives off heat
Project #4 “ *Nanocrystalline SiC Polymer Composites”
A main area of this research is concerned with optical fiber materials. This
includes developing fiber core and cladding materials with controlled refractive
indexes. Another project involves the design in transparent, low refractive index
**cladding materials. In addition to stringent optical and mechanical criterion, the
effect of ionizing radiation on optical and mechanical properties of these
materials is also characterized. This work is applicable to space environments and
to particle accelerators where scintillating optical fibers are used. Research
involves collaborations with Optical Polymer Research Inc. and Honeywell Space
Systems Group. The object is to use nanocrystallites of SiC as radiation sinks,
dissipating energy and decreasing the frequency of radiolysis events. Most
recently, progress has been made in solubilizing the nanocrystallite SiC in
polymer matrices. Transparent polymer/nanocrystallite SiC samples have been
prepared. The group is in the process of analyzing these new materials.
Helpful Definitions:
* nanocrystalline = crystalline particles < 30 nm in diameter
** cladding = optical confinement of light in certain frequencies
Faculty/Industry Collaborators:
Dr. Stephen Saddow (USF
Electrical Engineering) Dr.
Serguei Ostapenko (USF,
Nanomaterials and
Nanomanufacturing Research
Center)
Current funding: NSF
General Area/Focus:
Characterization of nanoporous
SiC layers
Application(s): Development of
the non-contact and nondestructive methodology
applicable to diagnostics of
epitaxial SiC films on wafers
with a nano-porous buffer layer.
Faculty/Industry Collaborators:
Dr. Robert Benson (Marine
Sciences, USF) Dr. L.
Stefanakos (Electrical
Project #5 “Spatially Resolved Characterization of Nano-Porous SiC
Layers”
This program addresses fundamental aspects of the nature and distribution of
point and extended defects in full-size bulk silicon carbide (SiC) wafers and
*epitaxial films for electronic applications. A specific goal of the program is
development of the non-contact and non-destructive methodology applicable to
diagnostics of epitaxial SiC films on wafers with a nano-porous buffer layer. The
superior properties of SiC make it an excellent candidate for high temperature,
high voltage, high frequency and high power applications. In addition, the large
Si-C bond energy makes this material resistant to chemical attack and ionizing
radiation, which is critical in terms of radiation stability and operation in a hostile
environment. However, the yield and performance of SiC based devices is limited
by poor substrate quality and subsequent epitaxial films. One approach to
improve homo-and heteroepitaxial films is to use a substrate containing a porous
buffer layer with controlled porosity and morphology. Nano-porous SiC can be
fabricated using UV light-assisted anodization, a procedure similar to the creation
of porous-Si layers. This approach in the area of **nano-technology has
demonstrated great benefits in reducing the defect concentration in epi-layers
deposited on porous structures compared to layers grown on standard SiC
substrates.
Helpful Definitions:
* epitaxial = to grow upon
** nano-technology = dealing in the size-scale of 10-9 meters
Project #6: “Hydrogen Production from the Electro-catalysis of Methane”
The production of hydrogen to meet the pending “Hydrogen Economy” mandate
is a formidable technical challenge. NASA utilizes and great deal of hydrogen as
Engineering, USF)
Current funding: NASA
General Area/Focus: Novel
production of hydrogen
Application(s): Development of a
novel process for the production
of hydrogen from common feed
stocks.
Faculty/Industry Collaborators:
Dr. Stephen Saddow (Electrical
Engineering, USF), Dr. George
Nolas (Physics Department, USF)
Current funding: USF
Interdisciplinary Award
General Area/Focus: Novel/safe
storage of hydrogen
Application(s): Development of a
novel process for the safe and
efficient storage of hydrogen to
meet the DOE onboard storage
mandate for 2010.
a fuel source for the current shuttle program. Unlike most fuels, hydrogen is not
found in nature in a free state but must be produced. We are investigating a novel
*electrocatalytic process that utilizes a natural gas feed-stock and converts it to
hydrogen along with other useful by-products. This novel process is portable,
requires very little energy and may be powered by photovoltaic cells.
Helpful Definitions:
* electrocatalytic = using a combination of a catalysts and an electronic bias
Project #7: “Si and SiC type-I clathrates: Scientifically interesting materials
with technological importance”
Scientifically interesting materials with technological importance for the
United States power generation and alternative fuel needs.” As the Chemical
Engineering component of the integrated team, my primary function will be the
integration of *clathrate technology to for hydrogen storage in applications of
solid-state fuel cells. The research is extremely timely with funding opportunities
related to the Hydrogen Economy Initiative. Hydrogen may actually be the only
meaningful link between renewable energy and chemical energy carriers such as
gasoline, propane, butane, etc. However, significant technical issues of safe
transport, storage and retrieval must be addressed. One of the outcomes of this
work is to demonstrate a safe, energy efficient method to store transport and
retrieve hydrogen for portable use. Herein we propose to begin an experimental
investigation on a unique material system that has potential technological
importance in power generation from waste heat and alternative fuels such as
hydrogen storage. The clathrate crystal structure is formed from two types of
face-sharing **polyhedra, or fullerene-like ensembles. This unique property lends
itself to novel properties, thus not only will this work be important from the
standpoint of potential applications but it also presents an opportunity to
investigate fundamental properties of novel crystal structures. Indeed, the
properties of SiC clathrates have, as of yet, not been investigated. The goal will
be to understand the properties as they relate to structure and stoichiometry and
thus develop optimization routes for thermoelectric and hydrogen storage and
fuel-cell applications. In the case of ***thermoelectrics, altering the thermal
conductivity of materials in general is difficult to control however this system
offers the opportunity to control the thermal as well as the electronic transport as
a function of structure and stoichiometry. In potential fuel-cell studies, the
polyhdra that form the crystal lattice lend themselves to unique structural
locations whereby hydrogen can interstitially be placed. We expect the work
under this proposed research to yield preliminary technological results that will
lead to further funding opportunities from DoD, DoE, NASA and the automotive
industry. In addition the new fuel cell initiative presented by our President in his
State of the Union Address will open the potential for substantial federal funding
in this area. This research is therefore very timely while providing the
environment for a distinctive educational opportunity for our students.
Helpful Definitions:
*clathrates = cage-like chemical structures
** polyhedra = many sided 3D geometric structure
***thermoelectronics = deals with the thermal and electrical transport through
materials
Faculty/Industry Collaborators:
Dr. Stephen Saddow (Electrical
Engineering, USF), M.G.
Mynbaeva, Ioffe PhysicoTechnical Institute,
Polytechnicheskaya 26, St
Petersburg 194021, Russia
Current funding: ONR
General Area/Focus: Production
of Semi-insulating SiC substrates
Application(s): Development of a
novel process for the production
of of Semi-insulating SiC
substrates for isolation purposes
in high temperature and high
power electric devices
.
Project #8: “Semi-insulating porous SiC substrates”
Semi-insulating SiC substrates were fabricated on a base of porous silicon
carbide made from *4H and 6H commercial SiC wafers. Porous SiC (PSC)
layers, 3 µm in thickness, were made by surface **anodization of SiC wafers
and then impregnated with excessive Si from a sputtered SiO2 film during
thermal processing at 1200 C. The processed structures were studied by
***Auger electron spectroscopy (AES), secondary ion mass spectroscopy
(SIMS) and X-ray photoelectron spectroscopy (XPS). The Si/C ratio in the
processed porous layers showed a measurable change from 1:1 to 2.3:1 due
to the diffusion of Si from the SiO2 film into the PSC layer during thermal
processing. The value of specific resistivity achieved was found to be
5 × 1011 cm at 470 K and 2 × 106 cm at 700 K, respectively, with an
activation energy of resistivity of 1.53 eV. Applications will include highpower, high-temperature, and high-density microwave integrated circuits and
vertical ****MESFETs
Helpful Definitions:
*4H, 6H = refers to the hexagonal crystal type of SiC
** anodization = to subject a material to electrolytic action as the anode of a cell
***AES, SIMS, and XPS = a series of material characterization techniques
****MESFETs = metal-semiconductor field effect transistor