Biofuel cells

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


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-


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)


1400 0

Desulfomicrobium baculatum


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.

Biofuel cells

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