research experience for undergraduates...
TRANSCRIPT
Research Experiencefor Undergraduates (REU)
REU 2104Materials for Energy and Sustainability
Idaho Conference on Undergraduate Research
Poster Presentations
coen.boisestate.edu/mse-reu
S
O
OH
S
O
OH
BrBr S
O
O
BrBr
S
O
OH
S
S
S
OH
O
Polymer B
Polymer A
HO1. SOCl22. S
O
On
S
S
S
O
O
Br
S
S
S
O
O
n
S
O
O S
O
O
R
Br
Bu3Sn
S
O
O
S
O
O
R
R = Fatty acid saturated chain
1. CH3MgCl2. Ni(dppp)Cl2
+
(49%)
(67%)
Polymer C
n
1. C16H30SSn2. Pd(PPh3)4
1. C16H30SSn2. Pd(PPh3)4
HO1. SOCl22.
1. SOCl22. HO
1. FeCl3
1. CV
1. Br22. AcOH
1. SOCl22. HO
1. Br22. AcOH
Synthesis and Polymerization of Novel Doubly-Polymerizable Thiophenes and Thiophene Substituted-Norbornenyl Monomers for Their Use in Photovoltaic Cells
Kareha Agesa, Pete Barnes, and Don Warner, PhD Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83706
Abstract
Energy Sources Characterization of Monomers Targeted Monomers
Polythiophenes are effective organic semiconductors because they are non-corrosive, easily synthesized, conveniently modified, and have lower manufacturing costs compared to silicon-based solar cells. Doubly-polymerizable thiophene monomers are preferred to traditional polythiophenes because they avoid synthetic challenges that lead to negative impacts in electrochemical properties. The synthesis of novel doubly-polymerizable thiophene monomers will lead to a variety of conducting organic polymers. Thus far, a 3-carboxylic-terthiophene monomer has been synthesized, and an esterification has resulted in a norbornenyl substituted 2,5-dibromothiophene. Polythiophene formation techniques will include more traditional chemical and electrochemical methods, specifically utilizing Grignard Metathesis Method and cyclic voltammetry. Then, ring–opening metathesis polymerization with a Grubbs’ ruthenium catalyst will lead to a thiophene substituted poly-norbornylene. These methods will work toward uncovering the reliability of organic polymers with a thiophene framework in the production and use of photovoltaic cells.
Polythiophenes: • Are conductive polymers • Alternative to silicon • Are low cost to manufacture and modify • Have a low band gap • Show delocalization of backbone electrons • Have electrical conductivity
• This project was supported by REU Site: Materials for Energy & Sustainability, Boise State University grant number DMR 1359344.
S
O
O
S
O
O
R
S
O
O
S
O
O
R
S
O
OH
Br
Bu3Sn
Br
S
O
O
BrBr
S
O
O
S
Monomer 3
Monomer 2Monomer 1
S
R = Fatty acid saturated chain
S
O
OH
BrBr S
O
OH
3-Thiophenecarboxylic acid
+
Conductive Polymers in Solar Cells
Research Objectives
Acknowledgements
Conclusion/Future Work Figure 1: Basic polythiophene
• Explore potential of thiophene framework in solar cells. • Prepare novel doubly-polymerizable thiophene monomers • Polymerize the monomers using Grignard Metathesis
Method (GRIM) and ring-opening metathesis (ROMP). • Characterize the polymers using electrochemical methods
such as cyclic voltammetry (CV) and Ultraviolet-visible spectroscopy (UV-vis).
• Polymer A utilized GRIM with the nickel catalyst. • Polymer B will be synthesized using CV or Fe3Cl. • Monomer 3 will be synthesized through metal-catalyzed cross-coupling,
then polymerization techniques will be attempted.
• Synthesize and characterize Monomer 3 • Characterize Polymer A using CV and UV-vis. • Synthesize and characterize Polymer B
Current Progress
• All monomer pathways require 3-Thiophenecarboxylic acid. • Norbornenyl-substituted thiophene capable of ROMP allowing for double
polymerization. • Monomer 1 polymerized through GRIM. • Monomer 2 possibly polymerized by chemical or electrochemical synthesis.
• Monomer 3 contains a fatty acid which may contribute to unique packing properties.
S SS
*
*
Fossil Fuels: • Are nonrenewable • Have potential to harm the
environment
Solar Energy: • Being researched as possible
energy alternative • Used in everyday items, such as
road signs and calculators • Utilizes photovoltaics to harvest
energy from the sun • Use silicon as a semiconductor
Monomer 1 in CDCl3 S
O
O
BrBr
a
bH
H
Hc
a
• Shows proton to carbon correlation • CH2 (geminal) shown in red • CH shown in black • Shows carbons directly attached to proton
Ø Spectra obtained: 1H, 13C, HSQC, HMBC, & COSY
Monomer 1 in CDCl3
What’s In The Air That You Breathe? Shelby Elkins, Dawn Estrella, Dr. George Murgel, and Dr. Sondra Miller
The College of Idaho Boise School District
College of Engineering, Boise State University
Methods: Two Micro-Orifice Uniform Deposition Impactors (MOUDI) collected PM ranging from 0.056 µm to 18 µm in diameter during 24-hour periods from the roof of a Boise State building. Aluminum foil substrates collected different sizes of particulates within the MOUDIs and were weighed to find the mass of the particulates. Two precipitation collection sites at the DCEW, located north of Boise, in the foothills, passively collected both wet and dry deposition in one-week cycles. Samples were rinsed with de-ionized water and poured through a filter in a vacuum pump to collect any particulates.
Background:
• PM10 are particles 10 µm or smaller in diameter • caused by human or natural chemical processes • small enough to be inhaled and stick in the respiratory system
• PM2.5 are particles 2.5 µm or smaller in diameter • created by human processes such as combustion • can accumulate deep in the lungs due to their small size
• Particles are further categorized by size: • nuclei mode particles (0.005-0.1 µm) • aerosols (0.1-2.5 µm) • coarse particulates (2.5-10 µm)
We used two collection sites to gather samples: • The first is on the roof of the Environmental Research Building (ERB) on campus at Boise State University (BSU), at approximately 2,800 feet • The second is at the Dry Creek Experimental Watershed (DCEW), located north of Boise in the foothills at an approximate elevation of 5,500 feet
Data Analysis:
Acknowledgements: • This research was partially funded by the National Science Foundation, Grant #DMR 1359344 References: • National Weather Service, “WFO Monthly/Daily Climate Data- Boise, Idaho”. Web. 25 July 2014. • Seinfeld, John H., and Spyros N. Pandis. Atmospheric Chemistry and Physics. New York: Wiley and Sons, 1998. Print. • United States Environmental Protection Agency, “Particulate Matter (PM)”, 18 March 2014. Web. 25 July 2014.
Objectives: • Identify chemical signatures and masses of
atmospheric PM • Potentially pinpoint the local and regional origins of
known contaminants • Monitor effects on air quality due to large natural
events, both weather-related and human-caused, during and following events
Below right: Dry Creek Collection Site.
Below left: Dry Creek filters, before and after processing.
Below: Foils from the MOUDI. The foil on the left is from one week prior, the foil on the right is from the same stack, during a fire event.
Abstract: We are currently examining atmospheric particulate matter (PM) samples in areas representing varying populations—urban and rural—by comparing data from two local sites. Atmospheric pollution is relevant to public health because it affects drinking water and respiratory health.
Above: MOUDI Stations on the roof of the ERB collect particulate matter.
Above: View of the Boise Front from the roof of the ERB at BSU (before fire event, July 2014).
Above: View of the Boise Front from the roof of the ERB at BSU (during fire event, July 2014).
Left: The temperature increase throughout July was matched with an increase in the mass load of dry PM collected. Boise experienced an influx of smoke due to nearby fires following July 15. There was a visible increase in the PM collection during that time as well.
Right: Limited wet deposition was collected this summer, as Boise does not experience much precipitation in June or July. The first and last weeks showed between two and three times the amount of PM as the middle three weeks.
Left: A steady increase in PM concentration was collected from our MOUDI when local fires brought smoke to the valley around July 15. The total concentration at the peak of the poor air quality (July 17) is three times that of the average for the week before and the week after.
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Synthesis of Model Compounds that Mimic the Primary and Secondary Coordination Sphere of Carbonic Anhydrase
Metalloenzymes play a critical role in the daily life of humans, animals, and plants. An example of this type of enzymes is carbonic anhydrase (CA), which is present in all living organisms. The main function of CA is the reversible hydration of CO2 to form bicarbonate, which it performs at a very high catalytic activity. Additionally, recent studies have determined that CA is the enzyme in plants that reacts with atmospheric carbonyl disulfide (CS2) and carbonyl sulfide (COS). The focus of this research is to gain insight into how carbonyl disulfide activation occurs at the zinc protein site through a synthetic modeling approach; where low molecular complexes are designed to mimic the active site and the reactivity of the enzyme. One of the most intriguing mechanistic questions concerning the catalytic cycle for COS activation by CA is the desulfurization of the zinc hydrosulfide that is formed. Our hypothesis is that the secondary amino acid residues (those that do not directly bind to the zinc center) play a key role by making the SH a better leaving group. Details of the reactivity and characterization of model complexes relevant to the catalytic cycle of CA will be presented.
Abstract
Introduc6on to Carbonic Anhydrase
N: Pyridine N atoms that bind to the zinc atom (primary coordination sphere). N-H: Hydrogen on amino groups bind to the SH group of the Zn-SH complex (secondary coordination sphere).
TPA as Suppor6ng Ligand for Synthe6c Models Synthesis of the Ligand
Conclusions
• Characterized many compounds relevant to the catalytic cycle of carbonic anhydrase. • The secondary coordination sphere of the active site of carbonic anhydrase plays a key role in the desulfurization step. • Hydrogen bonding affects the sensitivity of the Zn-SH complex in the presence of water. • The sulfonium ion character of the SH bond increases as hydrogen bonding increases shifting the -SH chemical shift downfield in the 1H NMR.
Acknowledgements
We thank the REU Site: Materials for Energy & Sustainability, Boise State University, Grant Number DMR 1359344.
Description • Metalloenzyme common to animals, plants, and bacteria. • Active site consists of a Zn(II) ion coordinated to three histidines and an aqua ligand. • Both Zn and Cd forms found naturally. • Active site requires hydrogen bonding residues for catalytic efficiency. Functions • Has a major role in CO2 transport and regulation of blood pH levels • Plays a critical role in COS (carbonyl sulfide) sequestration by plants • Has a high catalytic efficiency that approaches the diffusion-control limit
(2) Anders, E. et al. Chem. Eur. J. 2004, 10, 3091-3105. (3) Anders, E. et al. ChemBioChem 2007, 8, 530-536.
Reasoning • When ligand is complexed with Zn it has been shown to interact with heterocumulenes under basic conditions. • Easy to synthesize and modify to more accurately reflect the active site of carbonic anhydrase. • The ligand contains two hydrogen bond donor sites (atoms labeled in red).
Research Question: What effects does hydrogen bonding have on the hydrosulfide desulfurization in carbonic anhydrase?
(1)Manchester University, (2)*Boise State University, Department of Chemistry and Biochemistry, Boise, ID Martin Garcia Chavez 1, Ian Shaw 2, Jeff Barlow 2, Eric C. Brown*2
Research Ques6on Proposed Mechanism
Research Objec6ves
• Isolate and characterize Zn intermediates pertinent to the mechanism proposed. • Explain the chemistry fundamental to the formation of [ZnII-SH]+. • Evaluate the effect that hydrogen bond donors have on the formation of ZnII-SH complexes and their desulfurization. • Develop a catalytic cycle based on carbonic anhydrase.
Previous Studies Towards the Isola6on and Characteriza6on of a Zinc Hydrosulfide Complex
Hydrosulfide Complex Synthesis
Effects of Hydrogen Bond Donors
Future Studies
(1) Graphic of CA active site taken from Protein Databank: http://www.rcsb.org /pdb/cgi/explore.cgi?pdbId=1CA2
OZn
HisHis
His
HSZn
HisHis
His
O
O
H
SZn
HisHis
His
H- CO2
CO2
OZn
HisHis
His
S
O
HOZn
His HisHis
S
O
H
OH
H
H2O
A B C
DEH2S and CO2
Pathway A
Pathway B
SZn
HisHis
His
H H
H+
H2OOZn
HisHis
His
H H
FG- H+
- H2S
O=C=S
Hydrosulfide through Use of an Aprotic Solvent
1. Zn(ClO4)2 6H2O, CH3CN2. (CH3)4NOH3. S=C=O
NNN
NZn
SH+
Yield = 73%
ClO4-N N
NN
• Create the zinc hydrosulfide complex in the absence of water. The zinc hydrosulfide appears to be very sensitive to water.
• Conduct alkylation reactions with the zinc hydrosulfide complex to determine the nucleophilicity of the SH group.
• Determine the effects of hydrogen bond donors on the desulfurization of the zinc hydrosulfide.
0.05.010.0
7.508.008.509.00
+1
Crystal Structure of [(TPA)Zn-SH]+ Cationic Portion.
*
(1)
(1)
N
NH
N
N
HN
N
41.20 % Yield
A
A
B
B C
C
D
D
E
E
F
F
G
G
S: Residual Solvent
S
H
H
H
S
4-5 ppm region I
I
J
J
I
K
K K
K K
K 6-8.5 ppm region
F
A B
C
D E
F, IH
E, 6H
S
S: Residual Solvent
D, 3H
B, 3H
C, 3H A, 3H
1. Zn(ClO4)2 6H2O, Dry MeOH2. Anhydrous NaHS
NNN
NZn
SH
+ClO4
N NH Hδ
NNN
N
NH HN
• Based on the NMR spectrum, the Zn-SH complex was synthesized successfully albeit as a mixture of compounds.
• The SH peak is observed at -0.553 ppm. • The complex is labile in the presence of water.
NNN
NZn
SH +
NNN
NZn
HS
+
NHδ
NNN
NZn
SHN NH Hδ
+
No Hydrogen Bond Donors SH Chemical Shift: -1.520 ppm
One Hydrogen Bond Donor SH Chemical Shift: -0.929 ppm
Two Hydrogen Bond Donors SH Chemical Shift: -0.553 ppm
N
NN
NZn
SH
N
NH
N
NHN
N
N-benzyl-6-((((6-(benzylamino)pyridin-2-yl)methyl)(pyridin-2-ylmethyl)amino)methyl)pyridin-2-amine
NH
O
Br +
N
NH2+ B-
O O
OO
OO
HNa+
N
Br
N
N
Br
N
CH2Cl2
N,N-bis((6-bromopyridin-2-yl)methyl)(pyridin-2-yl)methanamine
63.3 %Yield
22
Synthesis of Ligand:
Synthesis of Compound 1:
+ NH2 NaOH,toluene/H2O 7 days
20
Funded by: National Science Foundation, Office of Special Programs, Division of Materials Research •Grant Number DMR 1359344
Abstract
High yield and affordable production of graphene and other two-dimensional
(2D) crystals has been a topic of considerable research in multiple disciplines.
Liquid exfoliation utilizing ionic surfactants has proven to be an effective way
to create 2D materials with potential uses such as lithium ion battery
electrodes, printable electronics, and thermal interface materials. The focus of
this research is the examination of the relationship between surfactants used in
the exfoliation process and the quality of the resultant 2D nanoflakes of
graphene and transition metal dicalchogenides (TMDs). To do this we first create
MoSe2, MoS2, and graphene suspended flakes via liquid exfoliation in an aqueous
solution of ionic surfactant. We then create dry powders of randomly stacked 2D
crystals for further use in device applications by freeze drying the solutions.
Finally we perform DOSY NMR Spectroscopy, IR Spectroscopy, Raman
Spectroscopy, Thermogravimetric Analysis, and Inductively Coupled Plasma
Atomic Emission Spectroscopy to elucidate the fundamental interactions of
surfactants with our 2D crystals.
Characterization
The Fundamental Interactions of 2D Nanomaterial Powders and Surfactants
Curtis Heishman, Richard Livingston, Dale Brown, and David Estrada
Research Relevance
Van der Waals Heterostructures
Fig 3
Techniques
Single Layer MoS2, MoSe2, Graphene Solutions Preparation
•80mg Bulk Powders
•40mL Soldium Cholate Solution (2% w/v)
•Tip Sonication in Ice Bath 30 min
•Centrifuge 25 min @ 4500 rpm
•Creates 2D Materials in Surfactant Micelles
e.g. Jonathan Coleman 5
Lyophilization to Create 2D Powders
•0.110 mBar, -53 C, 24 hours
Sodium Cholate
Ionic Surfactant
Fig 4
Lyophilization Data
Material MoSe2 MoS2 Graphene Graphene + MoS2
Volume of Solution 15mL 15mL 15mL 14mL
Mass Yield 0.1820 g 0.2930 g 0.2550 g 0.2677 g
Density of Solution 12.133 g/L 19.533 g/L 17.000 g/L 19.121 g/L
Labconco FreeZone 4.5L Graphene & Surfactant Flakes
Create a pellet of mixed 2D nanomaterials
• Cheap, Efficient, High Reproducibility, Easy To Work With
• MoSe2, MoS2, Graphene, WS2, WSe2
• Achieve a high quality ZT Value ZT = s2 σ T λ-1 (Thermoelectric Figure of Merit)
s = Seebeck coefficient (converting temperature to current) σ = Electrical Conductivity λ = Thermal Conductivity T = Temperature
MoSe2 Flakes Heated to 575 C
Characterization
Thermogravimetric Analysis 6
• MoS2 & MoSe2 + Surfactant Powders
• Heated to 1100 C, 50 C per minute, 21 minutes
• ~ 71% of Powder is NaCh Surfactant
• Surfactant Digests at Min 390 ̊C - Max 550 ̊C
• Yield @ ~20%, but does Sodium remain? Preliminary ICP MS anaylsis suggests yes
MoS2/Graphene Heterostructured Nonvolatile Memory
Fig 1
Common TMDs
Fig 2
TGA of MoS2 + Sodium Cholate Surfactant Powder
TGA of MoS2 + Sodium Cholate Surfactant Powder
IR Spectroscopy
MoSe2 + NaCh overlayed w/ Sodium Cholate MoSe2 after heating to 575 C
To Remove Surfactant
NaCh MoSe2
06/23/14
NaCh MoSe2
06/13/14
NaCh
06/13/14
1H NMR Spectroscopy
Evidence of Hydrolysis
Future Work
• ICP MS Analysis to determine levels of sodium doping
• Raman Spectroscopy to determine thickness of flakes
• Investigate potential to bind molecules to 2D flakes
• Find non-ionic surfactants that can be lyophilized
• Heat Flakes in Inert Atmosphere of Tube Furnace and analyze
Acknowledgements 1. A. K. Geim and I. V. Grigorieva, Nature 499 (7459), 419-
425 (2013).
2. Q. H. Wang, K. Kalantar-Zadeh, A. Kis, J. N. Coleman and
M. S. Strano, Nature Nanotechnology 7 (11), 699-712
(2012).
3. A. K. Geim and I. V. Grigorieva, Nature 499 (7459), 419-
425 (2013).
4. Seong, Maen-Je, Journal of Korean Physical Society Vol
58, No 4
5. Science 331, February 4, 2011, DOI: 10.1126 6. Dr. Jerry Harris, NNU
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• Harnessing electricity from heat is the concept of thermoelectricity.
• Examples of thermoelectric applications include power plant generators and refrigerating systems.
• Future applications for thermoelectric materials include implementing in motor vehicles to improve efficiency in gasoline consumption which is only at around 14-30% for conventional vehicles. [1]
INTRODUCTION
OBJECTIVE
1) Before performing any complex simulations, the atomic structure of skutterudite series, Co4Sb12-
2xTexGex , needed to be optimized.
• First Principle Calculations of crystal structure were performed using the program Vienna Ab-
initio Simulation Package (VASP) based on the Density functional theory (DFT). [4]
METHODS & PROCEDURE
Table 1. Average optimized lattice constant for atomic structure of Co4Sb12-2xTexGex, where x= 0, 0.5, 1, 2, & 3. Each column after the ‘x’ column represents data calculated from each concentration three different ways.
RESULTS & DISCUSSION
CONCLUSION
• Using computational modeling, the ground state structures of skutterudite series Co4Sb12-2xTexGex were successfully predicted.
• In comparison with experimental data, the DFT calculations for the lattice constant and volume were supported over the DFT+U method.
• The Co4Sb12-2xTexGex skutterudite is semiconducting, and its electronic band gap decreases as Te and Ge substitutions increase.
• Future work: further prediction of thermal conductivity properties of skutterudite series Co4Sb12-2xTexGex .
REFERENCE
[1] U.S. Department of Energy, “Where the Energy Goes: Gasoline Vehicles”, Energy requirement estimates are based on analysis of over 100 vehicles by Oak Ridge National Laboratory using EPA Test Car List Data Files, http://www.fueleconomy.gov/feg/atv.shtml
[2] The Nanometer Structure Consortium at Lund University, http://www.nano.lth.se/research/nano-energy/thermoelectrics?layoutmode=print
[3] Y. G. Yan, W. Wong-Ng, L. Li, I. Levin, J. A. Kaduk, M. R. Suchomel, X. Sun, G. J. Tan, X. F. Tang, ”Structures and thermoelectric properties of double-filled(CaxCe1-x)Fe4Sb12 skutterudites”, Journal of Solid State
Chemistry, in press (2014). [4] June Gunn Lee, Computational Materials Science An Introduction, CRC Press Taylor & Francis Group, Boca Raton, FL, USA, pp 180-200 (2012).
ACKNOWLEDGMENT
A special thanks to graduate student, Izaak Williamson, for his helpful discussions and aid with computational modeling setup for the calculations. Many thanks to, Dr. Lan Li, for her supervision and supportive guidance throughout the entire project. These research and educational activities were supported by the National Science Foundation, Office of Special Programs, and Division of Materials Research under Grant No. DMR 1359344.
• To develop the best thermoelectric materials that can conduct a maximum amount of electricity from small temperature gradients as well as withstand extremely high ones, a study is performed to investigate skutterudite series Co4Sb12-2xTexGex.
1Department of Math, Science, and Engineering, Cosumnes River College, Sacramento CA 95823 2Department of Materials Science and Engineering, Boise State University, Boise ID 83725
Logan Her1, Izaak Williamson2, Lan Li2
Materials by Design : Structures and Thermoelectric Properties of Skutterudite Co4Sb12-2xTexGex
What are Skutterudites?
• Compound with cage-type crystal structure formed by group 15 elements, featuring loosely bound guest (filler) atoms inside.
• Typically exhibit good intrinsic electrical transport properties and have a thermal conductivity that can be minimized by coordinating the filler atoms. [3]
• Experimental data validated computation with DFT and DFT+U for this skutterudite series.
• With DFT having a better representation for the atomic cell unit, the output files were used for the Electronic Density of States calculation to estimate a band gap at each concentration.
• General Formula: MxA4B12 – A = Fe, Ru, Co – B = P, As, Sb (group
15 elements) – Mx = filler atom
• Replace Sb with other species: Co4Sb12-2xTexGex
• Both lattice constant and volumes were calculated using DFT and DFT+U.
• Input files contained: XC- Exchange
Correlation Energy Functional
K-point coordinates for size of sampling the Brillouin Zone.
Lattice parameters & atomic coordinates
PP-pseudopotentials for each atomic species
• However, implementing thermoelectric devices into automobiles requires better and more improved thermoelectric materials still in development.
• Output files included: CONTCAR- relaxed
atomic structure CHGCAR- optimized
electronic density WAVECAR-
optimized wave density
2) The calculated structural data was compared with experiment.
3) Based on the validation with experiment, the method, i.e. DFT or DFT+U, would be selected for further use to determine the electrical conductivity properties of the compound.
• In both Figure 5 and 6, the conduction and valence bands are very close.
• This small range band gap indicates that the skutterudite is semi-conducting.
• The band gap can be minimized by increasing the concentration of Te and Ge substitutions.
x Experimentation Computation (DFT) Computation (DFT+U)
0 737.936(11) 756.27 752.85
0.5 732.975(10) 748.91 881.88
1 727.918(12) 744.03 794.33
2 716.39(2) 701.81 855
3 703.981(12) 721.7 847.01
Volume (Å3)
Table 2. Optimized lattice volume for atomic structure of Co4Sb12-2xTexGex, where x= 0, 0.5, 1, 2, & 3. Each column after the ‘x’ column represents data calculated from each concentration three different ways.
Figure 4. Optimized Co4Sb12 structure
Figure 2. A toms form the cage structure that is filled with filler atoms M and B atoms that form nearly-square planar rings.
Figure 3. SSH Secure Shell Client and File Transfer access the server to run and receive VASP calculations. VMD and p4v are both used for visual outputs from VASP.
Geometry Optimization Process for VASP
Figure 5. Electronic density of states (DOS) given as a function of energy for Co4Sb12. Vertical dotted line represents the Fermi energy, 𝐸𝐹. Core electrons are on the left with the Valence Band being the closest part on the left side of the Fermi line. Conduction band represent the right side.
Figure 6. Electronic density of states (DOS) given as a function of energy for Co4Sb11Te0.5Ge0.5. Vertical dotted line represents the Fermi energy, 𝐸𝐹.
x Experimentation Computation (DFT) Computation (DFT+U)
0 9.03662(4) 9.110858907 9.097107787
0.5 9.01633(4) 9.081218599 9.589741047
1 8.99555(5) 9.061538786 9.262686611
2 8.94781(7) 8.887053776 9.491395559
3 8.89584(5) 8.970463368 9.470189676
Lattice Constant (Å)
Figure 1. Electricity will be generated from the thermoelectric device due to the temperature gradient between cool air from the environment and waste heat from the hot exhaust through the Seebeck Effect [2].
Determining an Electropolish Procedure for Ni₂MnGa Alloys
Anneliese E. Laskowski¹, Nikole J. Kucza², Paul Lindquist², Peter Müllner² ¹ Department of Materials Science, University of Wisconsin Eau Claire, Eau Claire, WI, 54701 ² Department of Material Science & Engineering, Boise State University, Boise, ID 83725
Mo<va<on for Project
• Need to electrochemically remove surface defects caused by cuWng and mechanical polishing. Removing defects improves surface roughness and magneto-‐mechanical behavior in Ni₂MnGa alloys.
• Need a defect-‐free method of micro-‐machining single crystals into small fibers.
• Current electropolish methods used on this material are difficult to control because of short etch ^mes.
Acknowledgments We would like to thank Zachary Harris for his founda^onal work and Eric Rhoads for fabrica^on. This work was supported by the US Na^onal Science Founda^on through grant No. DMR-‐1359344 and DMR-‐1207192.
Literature Faust, Charles L., and Paul D. Miller. Con^nuous Method for Electropolishing Nickel and Nickel Containing Alloys. United States Patent Office, assignee. Patent 2440715. 4 May 1948. Print.
Conclusion and Beyond Conclusions: • Current Density of 2.4 mA/mm² produces a surface
roughness of 120 nm with minimal piWng at 75 s. • High current density yields an increase in material
loss; however, piWng is also increased. Future work includes: • Inves^gate the effec^veness of material removal and
surface roughness on a single wire specimen. • Study the effect of material removed vs. strain
response for Ni₂MnGa wires.
Analysis
The electropolish ^me was fixed at 90 s while the current density was varied. The weight loss was linear with current density, W = 0.0002 ^mes the current density with an R2 value of 0.95. Current densi^es above 10 mA/mm2 resulted in massive piWng and increased surface roughness, so those samples were not tested.
w = 0.0002c R² = 0.949
0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01
0 10 20 30 40 50
Weight Loss (g)
Current Density (mA/mm²)
Surface Roughness
Fig 1: Hand polished at 1200 grit with average surface roughness of 155 nm.
100
110
120
130
140
150
160
0 20 40 60 80 100 120
Ra (n
m)
Time (s)
The average surface roughness (Ra) varies over ^me and is minimum at 75 seconds.
Fig 2: Same sample electropolished at 2.3 mA/mm² with average surface roughness of 122 nm.
Method & Set-‐Up Sample Prepara^on
1) Hand Polish 2) Pre Electropolish Measurement • Op^cal Microscope • Op^cal Profilometer
3) Electropolish 4) Post Electropolish Measurement • Op^cal Microscope • Op^cal Profilometer
Experimental Setup A. Wash Sta^on B. Acid Bath
C. Power Supply
Anode/Cathode Anode = Sample Cathode = Nickel Plate Ion Solu^on/bridge = 10 wt% Sulfuric Acid, 20 wt% Water, 70 wt% Phosphoric Acid
(1)
(4) (3)
(2)
Finding the Right Current Density
2.4 mA/mm²
3.1 mA/mm²
30 s 75 s 105 s
• No piWng observed. • Polish scratches are
s^ll visible and samples are stained.
• Average pit diameter is 60.1 μm.
• Surface is uneven with a large distribu^on of piWng.
• Average pit diameter is 55.2 μm.
• Surface is reflec^ve with minimal piWng.
2.3 mA/mm²
TEMPLATE DESIGN © 2008
www.PosterPresentations.com
Investigation on Instruments and Measurement Techniques for the Thermoelectric Properties of Materials
Dwencel John Mamayson1, Tony V. Varghese2a, Dr. Yanliang Zhang2b, Andrew Wilson2b, Dr. Don Plumlee2b, Jacob Davlin2b
1 Science, Math and Engineering, Cosumnes River College 2a Material Science Engineering, Boise State University
2b Mechanical & Biomedical Engineering, Boise State University
Background
Objectives Method of Measurements
Improvements & Results
Proposed Changes & Future Works
Acknowledgement
To study and be familiar about the operations of the current instruments and measurement techniques for measuring thermoelectric properties of materials.
To improve these current instruments and measurement techniques for better measurements and results.
OPTIONAL
LOGO HERE
OPTIONAL
LOGO HERE
• Direct conversion of temperature differences on a material’s two sides into electricity is called the “Seebeck” effect.
• Direct conversion of electric current to temperature difference on material’s two sides is called the “Peltier” effect.
and/or
What is Thermoelectric Effect?
National Science Foundation; Office of Special Programs, Division of Materials Research and Research Experience for
Undergraduates (REU) Program [DMR-1359344] at Boise State University.
Application of Thermoelectric Effect:
• Thermoelectric generators, TEG (also called “thermoelectric modules”) are devices that use the “Seebeck” effect to harvest waste heat.
• N-type and P-type of the same material are connected electrically in series and thermally in parallel to form a thermoelectric module.
The order of set-up process: • Place the sample between
the Indium contact thermocouple for cold temperature (negative Seebeck voltage) on the bottom and the Indium contact thermocouple for hot temperature (positive Seebeck voltage) on the top.
• Place the heater on the top of the hot temperature Indium contact.
• Screw and tighten the plastic insulator for pressure application.
(Cross-Plane) Set-up for Bulk-Pellet Samples:
Set-up for Thick and Thin Film Samples:
The order of set-up process: • Place one side of the
glass with the sample on the top of the heat sink and the other on the (hot side) module.
• Place the Indium contacts for the cold and hot temperature. thermocouples on the respective sides of the sample.
• Place the plain insulator piece on the top of the Indium contacts.
• Place the Insulator with screws on the top of the plain insulator for pressure application.
• The application of high thermal conductivity Silicone thermal paste between the sample and the instrument:
In the Bulk-Pellet Sample Measurement Set-up:
• The installation of Styrofoam to the instrument:
Increased sample and set-up thermal interface conductance.
Reduced measurement error due to the thermal contact resistances.
Minimized the heat losses from convection and radiation heat transfer.
In the Thick and Thin Film Measurement Set-up:
• The alteration of the insulators’ orientation and addition of glass slide (above the Indium contacts an the sample) and (blue) tape bundle to the set-up: Balanced the
insulators. Abled to apply
maximum pressure on both sides.
Minimized the shattering of the glass-sample holder.
For the Bulk-Pellet Sample Measurement Set-up:
“Thermoelectric Generator for Efficient Automotive Waste Heat Recovery”
For the Thick and Thin Film Sample Measurement Set-up:
• Build a design that has pressure variation only to the
sample. • Initiate the thermal insulation idea using a foam-like
material with a very low thermal conductivity. • Separate the heat sink from the module.
• The silicone thermal conductive paste can be replace by an easier-to-clean, higher thermal conductive paste like silver paste.
• The Styrofoam material cover can be replace by a better foam-like material which has lower thermal conductivity.
• Fabrication of the design and then experimentation using materials with reported literature thermal properties to evaluate the accuracy.
“Graphical Result of Ceramic Material Measurements”
The overall results showed a significant difference between the thermal conductivity of the Plain Low Temperature Co-fired Ceramic (LTCC) and the Silver Thermal Vias LTCC .
The figure shows the Silver Thermal Vias LTCC on the left and the Plain LTCC on the right .
“Overall Ceramic Package TEG Device Schematic with Thermal
Vias”
Atomic Layer Deposition on Titania Nanotube Electrodes
for Sodium-Ion Batteries Michael A. Reinisch, Aaron Forde, Griffith Allen, Steven Letourneau, Riley Parrish, Hui (Claire) Xiong, Elton Graugnard *
Department of Materials Science & Engineering, Boise State University, Boise, ID 83725 USA (*email: [email protected])
Acknowledgments: This project was supported by the REU in Materials for Energy & Sustainability at Boise State University (Research grant number DMR 1359344), funded by the National Science Foundation. We also thank the students and staff of the Nanoscale Materials & Device Research Group (nano.boisestate.edu).
1. INTRODUCTION Background: • Lithium-ion batteries suffer from safety concerns and high
precursor cost • Sodium-ion batteries serve as cost-effective alternatives for
large-scale energy storage systems • Due to their size, sodium ions (ion radius: 1.06Å) do not
intercalate into anode materials efficiently as lithium ions (ion radius: 0.76Å)
Hypothesis: • Growth of TiO2 by atomic layer deposition will lower surface
energy and facilitate sodium-ion intercalation
4. ATOMIC LAYER DEPOSITION
2. MECHANISM
While charging, sodium ions adsorb to the sidewalls of the TNTs.
As the sodium-‐ion concentra;on increases near the sidewall, the ions begin to diffuse into the TNT’s structure.
6. DISCUSSION
TEM revealed that the TNTs synthesized by electrochemical anodiza;on have an average wall thickness of 15 nm and inner diameter of 80 nm.
Summary • TNTs offer performance
advantages through increased electrochemical ac;vity and poten;ally enhanced capacity.
• Increasing the TNT radius of curvature lowers its surface energy, thus improving sodium-‐ion intercala;on into the anode material.
• ALD deposited ultra-‐thin ;tania coa;ngs on TNT anodes should improve the baLery capacity and cycling stability of TNT anodes.
Electrochemical Anodiza1on
1. TTIP aLaches to TiO2 surface. IPA leaves as by-‐product.
2. Water reacts to form hydroxyl terminated surface.
3. IPA leaves as by-‐product. Cycle starts over, releasing TTIP.
5. SURFACE ENERGY Surfaces are higher energy because surface atoms are less ;ghtly bound than atoms in the bulk. Lowering surface energy improves sodium ion diffusion into the TNT walls.
Transmission electron microscope (TEM) images of TNTs aUer TiO2 atomic layer deposi;on (ALD). Thicker tube walls indicate growth towards the top of the TNTs. Thinner walls near the boLoms of the TNTs indicate that precursor residence ;mes were insufficient.
Surface energy, γ, is defined to be the Gibbs free energy per unit area.
Schema;c of ;tania nanotubes (TNTs) in a sodium electrolyte.
Titania Nan
otub
e
3. TITANIA NANOTUBES
Key:
Process repeats un;l the desired film thickness has been achieved.
Precursor combina1ons: 1. H2O with one of the following 2. Titanium (IV) Isopropoxide (TTIP)
Dimethylamino Titanium (TDMAT) Titanium Tetrachloride (TiCl4)
Progress to Date • Uniform growth of Al2O3 was
successful, valida;ng processing and characteriza;on procedures.
• Only minimal growth of TiO2 has been observed using TTIP or TDMAT despite published growth protocols.
• The lack of TiO2 growth is aLributed to the low vapor pressure of TTIP and TDMAT.
• ALD-‐TiO2 will be grown using TiCl4, which has a significantly higher vapor pressure than TTIP or TDMAT.
• Lack of growth with TiCl4 will indicate surface chemistry issues.
ICUR 2014
1. A posi;ve voltage of 25 V is applied to Ti foil through DC power supply for 30 min
2. As-‐prepared samples are rinsed with DI water and immersed in IPA for a few hours
3. 1.6 cm2 discs are punched out from anodized FOIL for baLery fabrica;on
Materials for Electrochemical Anodiza1on • Etchant/Electrolyte: Dilute Ammonium Fluoride (NH4F) in Formamide and water
• Two-‐electrode Cell: Working electrode – Ti foil Counter electrode – Pt mesh
Mechanical Properties of Silicon Carbide Micro-Fibers
Alexander J. Wirtza, Brian J. Jaquesb, and Darryl P. Buttb
aThe College of Idaho, bBoise State University
0
0.5
1
1.5
2
2.5
0 0.2 0.4 0.6 0.8 1 1.2
Stre
ss (
GPa
)
Strain (%)
Sample 3
Sample 8
Sample 15
Sample 12
Sample 23
Abstract
Background
Experimental Procedure
Acknowledgements
References
Results Silicon carbide (SiC) fibers have many notable properties such as low density, high elastic modulus, and high temperature mechanical strength. Such properties make these fibers desirable in engineering products such as aerospace heat-resistant tiles, fiber optics communications, and semiconductor electronics. These fiber were investigated as various processing speeds to increase the carbon to silicon carbide conversion may have effects on mechanical properties. Laser diffraction was used to measure the diameter of each fiber to accurately determine the mechanical properties of the processed fibers. Fracture strength and Young’s modulus were found and evaluated using Weibull statistics relative to processing parameters of the fibers.
Creation Process:
Carbon fiber tows were heat treated in a silicon-containing gas at different processing speeds to increase the amount of conversion from carbon to silicon carbide. The effects of the processing speeds on the mechanical properties should affect the silicon carbide conversion, and thus, the mechanical properties of the fiber. [3]
Laser Diffraction Benefits and Theory:
Rapid measurement: 2 minutes per sample Accuracy: ± 0.1 μm [5] Cost: << SEM and other forms of microscopy Bragg’s Law (Equation 1), along with Babinet’s
Principle, can be applied to determine the diameter (𝑎) of a carbon and/or silicon carbide fiber because the diffraction pattern of light around a small fiber mimics the single-slit experiment, with the exception of the light intensity [2] [4] (Figure 1). Variables in Equation 1 are defined in Figure 3.
𝒂𝒔𝒊𝒏𝜽 = 𝒏𝝀
𝒂 = 𝒏𝝀
𝐬𝐢𝐧 𝒕𝒂𝒏−𝟏 ∆𝒁𝟐𝑳
ACF LLC. provided four different samples for characterization:
• No Heat Treatment • 3 in/min
Precise cardstock test frames were fabricated using a CNC laser to provide a 1 inch gauge length
Individual fibers were fixed to the test frames with cement and a secondary frame was fixed on top of the fiber to provide a more rigid test fixture (Figure 2a).
The completed frames were cured for 24 hours before any further testing.
Mechanical Testing:
Laser Diffraction:
SiC Fracture Analysis: Weibull Statistics
Laser diffraction was conducted with a 5 mW helium-neon laser system.
Images of the diffracted laser nodes were captured and spacing was measured (similar to Figures 3 - 4)
Calculations were performed using Bragg’s Law in Equation 1 (variables defined in Figure 3)
The diameters measured from diffraction testing are shown in Table 1.
0.2μm/sec
Each test frame was mounted in a Shimadzu mechanical testing system (Figure 6). The frame sides were cut to isolate the fiber to the applied tension (Figure 2b). Mechanical testing: 10 N load cell Strain rate of 0.2 μm/sec
Young’s modulus (E) and fracture strength (σf) were calculated for each fiber.
An example stress vs. strain graph for 3 in/min fibers is shown in Figure 5.
Single Slit SiC Fiber
Figure 1
Equation 1
Figure 2a
Figure 4
Table 1
Figure 3
This research was made possible by Boise State University and the National Science Foundation’s Research Experiences for Undergraduates (REU) Program Award DMR-1359344. Special thanks to: Advanced Ceramic Fibers, LLC, Materials in Energy and Sustainability REU/RET
Director Rick Ubic, and the Advanced Materials Laboratory research group.
1. Carter, C. Barry, Norton, M. Grant. 2007. Ceramic Materials: Science and Engineering. Pg. 302-305. New York: Springer Science, Business Media, LLC. 2. Halliday, David, Resnick, Robert, Walker, Jearl. (2001). Fundamentals of Physics. Sixth Edition, Pg. 893-896. New York: John Wiley & Sons, Inc. 3. Hinoki, Tatsuya, Lara-Curzio, Edgar, Snead, Lance L. (2001). Mechanical Properties of High Purity SiC Fiber-Reinforced CVI-SiC Matrix Composites.
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN37831. 4. Li, Chi-Tang, Tietz, James V. (1990). Improved accuracy of the laser diffraction technique for diameter measurement of small fibers. Journal of Materials
Science, 25, 4694-4698. 5. Meretz, S., Linke, T., Schulz, E., Hampe, A., Hentschel, M. (1992). Diameter measurement of small fibers: laser diffraction and scanning electron
microscopy technique results do not differ systematically. Journal of Materials Science Letters, 11, 1471-1472. 6. Summerscales, John. (2014). Composites Design and Manufacture: Reinforcement Fibers. ACMC University of Plymouth, Plymouth University, Plymouth.
Conclusions: Weibull modulus for each fiber type was found
and can be used to better understand fracture mechanisms and to predict failure probability.
Treated fibers show two Weibull moduli which represent two distinct flaws causing failure.
Initial Weibull moduli (m1) increase as the processing speed decreases.
A sample size of 30 produced a below average Weibull distribution with low confidence. An increased sample size (for each distinct flaw) is recommended for more reliable data. [1]
Both fracture strengths and Young’s moduli decrease as processing speeds decrease (more C-SiC conversion), which is expected when compared to literature. [3] [6]
𝜃 𝐿
∆𝑍
2
𝐻𝑒𝑁𝑒 𝐿𝑎𝑠𝑒𝑟
𝑆𝑖𝐶 𝐹𝑖𝑏𝑒𝑟
λ = 632.8 𝑛𝑚
𝐿𝑖𝑔ℎ𝑡 𝐼𝑛𝑡𝑒𝑛𝑠𝑖𝑡𝑦
𝑛 = 1 𝑛 = 2
Analogous to
• 5 in/min • 1 in/min
Figure 2b Fiber Preparation:
Diameter Results Fiber Set Average Diameter (μm) Standard Deviation (μm)
No H.T. 7.1 ±0.4
5 in/min 7.2 ±0.4
3 in/min 7.5 ±0.3
1 in/min 7.2 ±0.3
Table 1
Figure 6 Figure 5
-5
-4
-3
-2
-1
1
2
-2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
lnln
(1/P
s)
ln(σf)
No H.T.
1 in/min
3 in/min
5 in/min
Fiber Set Young’s Modulus (GPa) Fracture Strength (GPa) No H.T. (n=30) 240 ± 57 3.5 ± 0.9
5 in/min (n=30) 210 ± 35 1.6 ± 0.9
3 in/min (n=30) 220 ± 23 1.4 ± 0.7
1 in/min (n=30) 190 ± 37 0.5 ± 0.5
m = 3.7
m2 = 1.2
m2 = 1.8
m1 = 6.9 m1 = 3.9
m2 = 0.9
m1 = 9.4
Table 2
Mechanical Properties:
Figure 7
SEM Fractography and Imaging: a) No H.T. fracture surface b) No H.T. fiber surface c) 5 in/min fiber tow d) 3 in/min fracture surfaces
c
b
d
Weibull statistics (Figure 7) were used to determine the Weibull modulus (m) by plotting a linear relationship between fracture strength (σf) and probability of survival (Ps). [1]
a
Synthesis of Amorphous Titanium Dioxide Nanotubes as Anode for Sodium-Ion Batteries
Aaron Forde#, Michael Reinisch&, Riley Parrish,§ and Hui (Claire) Xiong§
#Department of Chemistry, University of Wisconsin-Stout &Department of Chemistry, University of Arkansas
§Department of Materials Science and Engineering, Boise State University Abstract
Amorphous *tanium dioxide (TiO2) nanotubes show promise as a next genera*on electrode material for sodium ion ba=eries. Their desirable characteris*cs are high surface area to volume ra*o, intercala*on ability with sodium ions, low environmental impact, and rela*ve ease of synthesizing by electrochemical methods. In this research we have tried to op*mize the amorphous TiO2 nanotubes for sodium-‐ion ba=ery systems by varying the physical parameters of the nanotubes. Primarily we are looking at how the inner diameter (I.D.) and wall thickness (W.T.) of the nanotubes affect sodium-‐ion ba=ery func*onality. The amorphous TiO2 nanotubes are synthesized by electrochemical anodiza*on of Ti foil. To increase the wall thickness of the nanotubes atomic layer deposi*on (ALD) was used to deposit TiO2 on the surface of the nanotubes. To test for op*mal inner tube diameter we anodize the Ti at varying voltages. All electrodes are tested as a sodium half-‐cell with sodium metal as the counter electrode.
Background TiO2 Nanotube Inner Diameters
Summary and Future Plans
SEM Imaging
Acknowledgements
Why use Na-‐ion
• Intercala*on methods similar to the well established Li-‐ion ba=ery systems
• Li-‐ion and Na-‐ion have similar characteris*cs
• Sodium is a globally abundant and cheap material
Challenges of Na-‐ion
• Does not intercalate well with conven*onal electrode materials
• Many Na-‐ion ba=ery systems suffer capacity fading for low charge/discharge cycles.
• Lower energy density than Li-‐ion ba=ery systems due to larger mass
Charging the ba=ery moves Na-‐ions from the cathode (red) to the anode (blue)
Discharging the ba=ery moves Na-‐ions from the anode (blue) to the cathode(red)
Advantages of Nanostructures Challenges of Nanostructures
Experimental
TiO2 Synthesis for I.D. Experiments
• Voltage: 20, 25 or 30 V • Time: 2 hours • Electrolyte: Ethylene glycol with dissolved
ammonium fluoride (2% water by volume) • Counter Electrode: Pla*num Mesh
• 2032 Type Coin Cells • Metallic Na counter-‐electrode • 1M NaClO4 in propylene carbonate
electrolyte • .02 mA g-‐1 discharge rate • 0.5-‐2.5 V
Coin Cell Fabrication
TiO2 Synthesis for W.T. Experiments
• Voltage: 25 V • Time: 30 minutes • Electrolyte: Formamide with dissolved
ammonium fluoride (5% water by volume) • Counter Electrode: Pla*num Mesh
AnodizaDon Parameters AnodizaDon Parameters
• Greater surface area to volume ra*o allows for more surface-‐electrolyte interac*on.
• Nanostructures have enhanced diffusion mechanisms compared to bulk materials
• Enhanced surface energy of nanostructures can cause unwanted side reac*ons
• Irreversible capacity lose upon first charge-‐discharge cycling
Characterization • Images of TiO2 nanotubes where obtained
by SEM imaging
• Electrochemical characteriza*on was obtained by galvanosta*c cycling of the half-‐cells
References
Nanotube W.T. Results Nanotube I.D. Results Future Plans
No electrochemical results where obtained for nanotube wall thickness experiments due to problems with deposi*ng TiO2 onto the nanotubes
The I.D of the E.G. samples could not be measured directly due to limita*ons of our imaging techniques. The I.D of E.G. samples where obtained from referencing Grimes and using linear interpola*on.
Grimes, C. A New Benchmark for TiO2 Nanotube Array Growth by Anodiza*on. Journal of Physical Chemistry C, 7235-‐7241.
Ethylene Glycol 1 Ethylene Glycol 2 Ethylene Glycol 3
Ethylene Glycol 1 Ethylene Glycol 2 Ethylene Glycol 3
Electrochemical Performance
Cycling Stability
Has the highest capacity (160 mAh/g) of the samples
Has by far the lowest capacity (55 mAh/g)
Shows good stability for 12 cycles then starts to fade
Fairly stable cycling though out the 20 cyles
The most stable of the samples measured
Shows fairly high capacity (110 mAh/g)
• Ethylene Glycol 1 shows the highest capacity, but suffers from capacity loss
• Ethylene Glycol 2 shows a useful capacity and seems to be fairly stable
• Ethylene Glycol 3 is the most stable but does not have useful capacity
• ALD process will have to be figured out before obtaining results on W.T
• More cycling will have to be run to determine if using these nanotubes will be useful as anodes for Na-‐ion ba=ery systems.
NSF REU Materials for Energy and Sustainability for providing me the opportunity to par*cipate in research