biofuel cells arkady a. karyakin faculty of chemistry, m.v. lomonosov moscow state university,...
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Biofuel cells
Arkady A. KaryakinArkady A. Karyakin
Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow, RussiaRussia
Hydrogen-oxygen fuel cell
Bioelectrocatalysisis an acceleration of electrode reactions by biological catalysts
Enzymes Whole cells
Biofuel cells
Enzyme electrodes Intact cell based
Thermodynamics of cathode reactions
E, NHE
1.85 V
1.2 V
0.6 V
H2O2/H2O
O2/H2O
O2/H2O2
Intact cell based fuel cells
• produce oxidizable compounds;• wired to the anode via mediators;• direct bioelectrocatalysis.
Fuel cells based on bacteria producing oxidizable compounds
• separated compartment of bioreactor and fuel cell;
• same anode compartment.
Oxidizable compounds:
H2 – Clostridium, E. coli, Rhodobacter (phototrophic) etc.
H2S, S – DesulfomicrobiumFormate – Clostridium butiricum
Fuel cells based on intact cells wired with diffusion free mediators
cell wall respiratorymembrane
substrate
product
medox
medred
electrode
hexacyanoferateazines
thioninesafranineneutral redazur A
indophenolquinones
1,4-naphthoquinone1,4-benzoquinone
Microbial fuel cells based on direct bioelectrocatalysis
Gil, G. C.; Chang, I. S.; Kim, B. H.; Kim, M.; Jang, J. K.; Park, H. S.; Kim, H. J. Biosensors & Bioelectronics 2003, 18, 327-334.
Electroactivity of Shewanella putrefaciens
A – air exposed cellsB – air exposed with lactateC – no air, but at + 200 mVD – at +200 mV with lactate
Kim, B. H.; Ikeda, T.; Park, H. S.; Kim, H. J.; Hyun, M. S.; Kano, K.; Takagi, K.; Tatsumi, H. Biotechnology Techniques 1999, 13, 475-478.
Acetate enriched consortium on graphite electrode
Lee, J. Y.; Phung, N. T.; Chang, I. S.; Kim, B. H.; Sung, H. C. Fems Microbiology Letters 2003, 223, 185-191.
Current response of Desulfobulbus propionicus
Holmes, D. E.; Bond, D. R.; Lovley, D. R. Applied And Environmental Microbiology 2004, 70, 1234-1237.
Enzyme based fuel cells
How to involve enzymes in bioelectrocatalysis?
Use of mediators:
Direct bioelectrocatalysis:
e
S
P-
S u b stra te O x id izedS u b stra te
O xid o red u cta se
M M redox
E le c tro d e
B.A. Gregg, A. Heller. Anal. Chem. 62 (1990) 258
Wired glucose oxidase
G lu co se
G lu c . a c .
O s+ /2+
O s+ /2+
O s+ /2+
hyd ro g e le_O s
+ /2+
O s+ /2+
Wiring of glucose oxidase
Heller, A. Physical Chemistry Chemical Physics 2004, 6, 209-216.
E = -0.195 mV (Ag|AgCl)
Wired bilirubin oxidase
E = 0.35 V (Ag|AgCl)
Heller, A. Physical Chemistry Chemical Physics 2004, 6, 209-216.
Actual characteristics of small batteriesCell Li-MnO2 Alkaline Zn–air Glucose–air
Intended site of use External electronics
External electronics
Subcutaneous tissue
Package/case Steel Steel None
Anode Li Zn Wired GOx
Cathode C(MnO2) C(Mn) Wired BOD
Electrolyte Organic 6 M KOH pH 7.4 saline buffer
Smallest size, in mm3 200 50 0.01
Power density, in W/L 300 150 1
Specific energy, in Wh/L 650 1800 50000
Heller, A. Analytical And Bioanalytical Chemistry 2006, 385, 469-473.
Hydrogen-oxygen energy sources
Turbines effective starting from MWt
High temperature H2-O2 fuel cells
high temperature (>850 C), fragile
Alkaline H2-O2 fuel cells low energy density
Pt-based H2-O2 fuel cells require Pt as electrocatalyst
Problems with Pt-based electrodes
• Cost and availability;
• Poisoning with CO, H2S etc.;
• Low selectivity.
Fuel cell cost problems
1 kW $ 200 - 2000
$ 10 000- $ 100 000
50 kW (<$ 10 000)
Dinamics of Pt cost
1960 1970 1980 1990 200002468
10121416182022242628
Pt
pri
ce/
US
$ g
-1
year
Available amount of Pt
Annual production:
180 tonnes
Assured resources:
100 000 tonnes
every year: >60 · 106 cars
50 kW engines > 6 000 tonnes Pt
2 g of Pt per kW
Poisoning by fuel impurities
Reforming gas (H2): 12.5 % of CO
Pt electrodes: -under 0.1% CO activity irreversibly decreases 100 times after 10 min;
- inactivation by H2S is 100 times more efficient.
Solution:increase of potential Short circuit
Low selectivity problems
Contamination of electrode space
Decreased efficiency of energy conversion from 90% to 40-60%
Pt – catalyst of both H2 oxidation and O2 reduction
BIOELECTROCATALYSIS
S2P2
Berezin I. V., Bogdanovskaya V. A., Varfolomeev S.D., M.R. Tarasevich, A.I Yaropolov. Dokl.Akad.Nauk SSSR (Proc. Acad. Sci.) 240 (1978) 615-618
Direct bioelectrocatalysis
OHeHO Laccase22 244
Est = 1.2 V
A.I. Yaropolov, A.A. Karyakin, S.D. Varfolomeyev, I.V. Berezin. Bioelectrochem. Bioenerg. 12 (1984) 267-77
Direct bioelectrocatalysis
222 HeH eHydrogenas
Equilibrium H+/H2 potential
Hydrogenase electrodes on carbon filament tissue
0
500
200
(3)
(2)
(1)
j/A cm-2
Er/mV
H2 (1), Ar (2) and CFM blank electrode (3)
How to involve hydrogenases in bioelectrocatalysis?
•sorption (surface choice & pretreatment);
• promotion by polyviologens;
• surface design by conducting polymers.n
CH2
CH2
N N
Br- Br-
N
R
N N
R R
n
-e-
Direct bioelectrocatalysis
Electrode E/c activity
hydrogenase Carbon material Ео, мВ Imax, А/cm2
LSG-240 173 2 Desulfomicrobium baculatum TVS 445 5
Lamprobacter Modestogalofilum
TVS 8 115
LSG-240 12 40 Thiocapsa roseopersicina
TVS 1 600
LSG-240 16 200 Thiocapsa roseopersicina (homogeneous) TVS 1,5 700
D.baculatum
0,5
200
i/ mA cm-2
Er/mV
without promoter
Th. roseopersicina
D.baculatum
CH2
CH2
N N
n
Effect of promoter
Surface design by conductive polymers
N
R
N N
R R
n
-e-
-(CH2)12O3-N+ N+-CH3, 2PF6-
-(CH2)12-N+(C6H13)3 ,BF4-
R: -(CH2)12-N+ N+-CH3, 2PF6-
Hydrogenase electrodes(a) adsorption
2
1
100
300
j/A cm-2
Er/mV
H2 (1) and Ar (2), sweep rate 2 mV/s
Hydrogen fuel electrodes
0
0.5
1
1.5
2
2.5
3
3.5
4
0 50 100 150 200
E / mV
I / m
A c
m-1
T.roseopersicina 50C
Pt 50C 3000 rpm
Bioelectrocatalysis – surface modification
Hydrogenase from Thiocapsa roseopersicina
Carbon material I max, А/см2 Еo, мV
LSG direct 200 22
TVS direct 700 1,5
LSG + polyviologen 750 0
LSG + polypyrrole-viologen 1400 0
Different hydrogenases in bioelectrocatalysis
electrode E/c activity
enzyme Carbon material I max, А/см2 Еo, мV
Lamprobacter Modestogalofilum (homogeneous)
LSG + polypyrrole-viologen
1200 -6
Thiocapsa roseopersicina (homogeneous)
LSG + polypyrrole-viologen
1400 0
Desulfomicrobium baculatum
LSG + polypyrrole-viologen
1700 -6
Current-voltage curves
-20
0
20
40
60
80
100
-150 -100 -50 0 50 100 150 200
E, mV
% o
f I
max
.
D. baculatumT. roseopersicina
Kinetics of hydrogenase electrodes
RT
F
iRT
F
i
RT
F
RT
F
i
oo
1exp
1exp
1
12exp2exp
2
21
"' EEE ee
Catalytic properties
Electrode/enzyme Enzyme sorpt-
ion, pmol/cm2jo
µA/cm2
jo per active
center, A 1019
Th.roseopersicina/TVS-direct
22±3 40±4 30±5
Th.roseopersicina/LSG+polypyr.-violog. 45±4 72±3 26±3
L.modestogalofil./LSG+polypyr.-violog.
42±4 62±1 24±1
D. baculatum/ LSG+polypyr.-violog.
40±4 130±20
53±8
Pt, pH 7.0 <10 <0.1
jmax
mA/cm2
0.7±0.1
1.4±0.2
1.2±0.2
1.7±0.2
ke/c s-
1
160
160
140
220
kkin s-
1
120
120
100
450
0 20 40 60 80 1000
500
1000
1500
2000
2500
j, A
/cm
2
% H2
Dependence on H2 content
D. baculatum/ LSG+polypyr.-violog.
Pt-vulcan, 1 M H2SO4
Poisoning by fuel impuritiesReforming gas (H2): 12.5 % of CO
Pt electrodes: under 0.1% CO activity irreversibly decreases 100 times after 10 min
Hydrogenase el-ds: -not sensitive up to 1% of CO;-reversibly restore activity after inhibition;
- not sensitive to 5 mM Na2S.
Tolerance to oxygen
70
75
80
85
90
95
100
105
65707580859095100% of hydrogen
% o
f in
itia
l act
ivit
y
nitrogen
air
Stability of hydrogen enzyme electrode at 80° С
0
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
0.009
0.01
0 1 2 3 4 5 6 7 8
time, hours
I, А
/см
^2
Hydrogen-oxygen biofuel cell
H2 2H+ + 2e-
0,5
200
E r /mV
Hydrogenase
O2 + 4H+ + 4e- 2H2O
-0.4
0800 1200
i /m
A c
m-2
E/mV
Laccase
Theoretical
Hybrid enzyme-microbial fuel cell
a consumption of biogas (microbiological H2) with hydrogen enzyme electrodes
Enzyme electrode consumes H2 from microbial media
0 10 20 30 40 50 60 70-600
-400
-200
0
2
1
Pot
enti
al, m
V v
s. A
g/A
gCl
Time, h(1) – criogel PVA with microbial consortium(2) - polyperchlorvinyl with spores of C. pasterianum
Enzyme electrode consumes H2 from microbial media
0 50 100 150 2000
100
200
300j, A
cm
-2
Er, mV
1 2
Hydrogenase-C.pasterianum electrode(1) – in cultural medium(2) - in H2 saturated solution
CONCLUSIONS
Enzyme electrodes are advantageous:• a completely renewable source;• solve problems:
- selectivity;- poisoning by fuel impurities;
• activity in neutral solutions similar to Pt in sulfuric acid;
• able to consume H2 directly from microbial media.