http://www.hnei.hawaii.edu Realizing Enzymatic Biofuel Cells Through Nano-Engineering Realizing Enzymatic Biofuel Cells Realizing Enzymatic Biofuel Cells Through Nano Through Nano - - Engineering Engineering Bor Yann Liaw Bor Yann Liaw Electrochemical Power Systems Laboratory Electrochemical Power Systems Laboratory Hawaii Natural Energy Institute Hawaii Natural Energy Institute School of Ocean and Earth Science and Technology School of Ocean and Earth Science and Technology University of Hawaii at Manoa University of Hawaii at Manoa 1680 East 1680 East - - West Road, POST 109, Honolulu, HI 96822 West Road, POST 109, Honolulu, HI 96822 (808) 956 (808) 956 - - 2339, 2339, [email protected][email protected]The 4 th US-Korea Forum on Nanotechnology, April 26, 2007, Hawaii
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http://www.hnei.hawaii.edu
Realizing Enzymatic Biofuel Cells Through Nano-Engineering
Electrochemical Power Systems LaboratoryElectrochemical Power Systems LaboratoryHawaii Natural Energy InstituteHawaii Natural Energy Institute
School of Ocean and Earth Science and TechnologySchool of Ocean and Earth Science and TechnologyUniversity of Hawaii at ManoaUniversity of Hawaii at Manoa
1680 East1680 East--West Road, POST 109, Honolulu, HI 96822West Road, POST 109, Honolulu, HI 96822(808) 956(808) 956--2339, 2339, [email protected]@hawaii.edu
The 4th US-Korea Forum on Nanotechnology, April 26, 2007, Hawaii
Electrochemical imaging ellipsometry + QCMMass transport
In situ characterization of permeability relative to direction of flowPorosity, pore/channel size, accessible surface area
Need for In Situ CharacterizationsNeed for In Situ Characterizations
In today’s nano-material and bioengineering research, control of materials synthesis and process require fast, non-intrusive, in-situ characterization over a large sample area. For enzymatic biofuel cell applications, such in situ, non-intrusive observations are highly desirable. Example:
Imaging ellipsometry + quartz crystal microbalance (QCM) + electrochemical techniques (e.g., CV, EIS), to study nano-materials and their properties:
images of co-immobilized Alexa-labeled dehydrogenase
(green) and TAMRA-labeled lysozyme (red) in (A) Eastman
AQ 55 (B) chitosan. (Scale bars: 50 µm.)
LSCM images of ADH tagged with Alexa-488 entrapped in (A) Eastman AQ 55 polymer matrix: 2-D slice; (B): 3-D reconstruction from 2-D slices; (C): Nafion: 2-D slice. (Scale bars: 50 µm.) A B C
A. Konash et al. J Mat. Chem. 16 (2006) 4107.
Micro and Nano Materials SynthesisMicro and Nano Materials Synthesis
Correlation of mean pore size dversus freezing duration
0
20
40
60
80
100
120
140
160
180
0 1 2 3 4 5 6 7 8 9 10
Time (h)d
( µm
)
d
d = -125.8*t^-0.6464+171.4
Scaffolds made from 1 wt% chitosan in 0.4 M acetic acid solution frozen under different durations: (a) 2 h, (b) 4 h, (c) 6 h, and (d) 8 h; scale bars = 200 µm.
a b
c d
DET in PQQDET in PQQ--GDHGDH--ChitosanChitosan--CNTCNT
-0.4 -0.2 0.0 0.2 0.4
-0.4
-0.2
0.0
0.2
0.420 mV/s
b
a
i/µA
E/V(vs.Ag/AgCl)
Kinetic curves of CHIT-CNT and PQQ-GDH-bound CHIT-CNT films in 0.1 M PBS with 0.1 M glucose, 0.8 mM PMS and 0.02 mM DCPIP. Insets: (left) linear fit plot and (right) the absorbance spectra of DCPIP at 600 nm with PQQ-GDH-bound CHIT-CNT film with time
500 550 600 650 700 750
0.2
0.4
0.6
0 1 2 3 40.3
0.4
0.5
0.6
0 1 2 3 4
0.2
0.4
0.6
A
λ/nm
A=0.6394-0.1584*t
CHIT-CNTs
CHIT-CNTs-GDH
A
t/min
νDCIP=0.0111 mM/min
CHIT-CNTs-GDH
CHIT-CNTs
At/min
CV of (a) PQQ-bound CHIT/GCE and (b) PQQ-bound CHIT-CNT/GCE in 0.1 M PBS at 20 mV/s
Current & Ellipsometric AnglesCurrent & Ellipsometric Angles
1.2 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6
31.0
31.5
32.0
32.5
33.0
33.5
34.0
34.5
P6P2P4
d(Ψ)/dt
P5P3
P2
P1
Ψ
Current
Ψ (d
eg)
Voltage vs. Ag/AgCl (V)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Cur
rent
den
sity
(mA
m뷵
-2)
- d(Ψ
) / d
V +
3.2
(de
gec븉
-1)
1.2 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6119
120
121
122
123
124
125
126
127
128
129
d(delta)/dV
Current
Delta
∆ (d
eg)
Voltage vs. Ag/AgCl (V)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
D2D3
D6 D5
D4
D1
Cur
rent
den
sity
(mA
m뷵
-2)
-2
0
2
4
6
8
d(∆
) / d
V (d
egec븉
-1)
Reduction of MG to Reduction of MG to ll--MGMG
In the reduction phase: the mass deposition was driven by adsorption, followed by electrochemical reduction of MG to l-MG
Faraday’s law
)(•
)(
)(•
••
0
tinF
Mdttdm
dttinF
Mm
QnF
Mm
T
=
=
=
∫
Ads
orpt
ion
Red
uctio
n of
MG
Mass & Mass & ∆∆
The progression of ∆ and d(∆)/dt follows mass changes.
Mass, Current, & Mass, Current, & ΨΨ
The progression of Ψ and d(Ψ)/dt reflect both mass and chemical changes in the film.
ConclusionConclusion
Enzymatic bio-fuel cells need delicate optimization of electrode fabrication, which requires pore structure engineering, from macro- to meso-scale.Nano-material synthesis and electrode fabrication require in situ observations and non-intrusive characterizations of the process.Several intriguing in situ characterization techniques were demonstrated of their utility:
Fluorescence and polarizationImaging ellipsometry + QCM + Electrochem. tech.Microporometry
Thank you for your attention!Thank you for your attention!
AcknowledgementsAcknowledgements
Funding Support:ONR, Hawaii Environmental and Energy Technologies (HEET) initiative (R. Rocheleau, PI)DCI Postdoctoral Fellow Research ProgramAFOSR, MURI Program (P. Atanassov, PI)
Contributors:Faculty: Michael Cooney, David Jameson, Shelley MinteerPostdocs: Wayne Johnston, Forest Quinlan, Vojtech Svoboda, Stacey Konash, Dongmei Sun, Daniel ScottStudents: Chris Rippolz, Mona Windmeisser, Swati Nagpal, Ruey Hwu, Eric Brown