YGShul

7/27/2019 YGShul

1/48

Nano Material Applicationsin Fuel Cell

Dept. of Chemical Eng. Yonsei Univ.

Prof. Y.G. Shul, H.S. Kim

7/27/2019 YGShul

2/48

Nano Materials in Fuel Cell

Hydrogen

Release Catalyst Novel Anode Catalyst

Organic-Inorganic

Membrane

7/27/2019 YGShul

3/48

Fuel Cell Applications

Heteropolyacid(HPA)-SiO2 nanoparticles for high

temperature operation of a direct methanol fuelcell

Preparation and characterization of new carbon

for fuel cell application Pulse Electrodeposition for Preparing PEM Fuel

Cell Electrode

Investigation of alloy catalyst for acceleratinghydrogen release from NaBH4

7/27/2019 YGShul

4/48

In this study

SiO2

Heteropoly acid

Nano scale. .. .

..... .

...

. ... .

. .

..... .

.... .

.

. .. ...... .

.... .

.. .. ...... .

.... .

.. .. ...... .

.... .

.. .. ...... .

.... .

.

. .. ...... .

.... .

.. .. ...... .

.... .

.. .. ...... .

.... .

.. .. ...... .

.... .

.

Preparation nanohybride particle (HPA/SiO2)By micro emulsion technique

Characterization :

TEM, Solid state NMR, TMP adsorption, N2 adsorption, FT-IR

7/27/2019 YGShul

5/48

Heteropolyacid-SiO2 nanoparticles

TEM image of heteropolyacid-SiO2 nanoparticle(R=2, HPA 30%, 24hr)

TEM image of heteropolyacid-SiO2 nanoparticle(R=2, X=30%, 12hr)

100 nm 100nm

R= [H2O]/[AOT]X=[Heteropolyacid]

7/27/2019 YGShul

6/48

31P MAS NMR

Chemical shift (, ppm)

-20-18-16-14-12-10

Heteropolyacid

100nm

500nm

Bulk

Dehydration

Fig. 31P MAS NMR spectra of heteropolyacid and HPA/SiO2

H3PW12O406H2O

-15.6ppm

-15.3ppm

-15.1ppm

-15.0ppm

Referenced from

- M.Misono et al., J.Phys.Chem.B., 104 (2000) 8108

- F.Lefebvre et al., J.Chem.Soc.Chem.Commun, (1992) 756

Dehydration of heteropolyacidHeteropolyacid < nanoparticle < Bulk powder

Trapping of acidic proton to OH group

Si

OHH+

Si

OHH+

Si

OHH+

34012 ][ OPW

7/27/2019 YGShul

7/48

13C CP MAS NMR

13C CP MAS NMR spectra(a) thiol- and (b) sulfonic-functionalized heteropolyacid-SiO2 nanoparticle.


0102030405060

(a)

(b)

27.9 ppm

11.4 ppm18.2 ppm

54.0 ppm


0102030405060

(a)

(b)

27.9 ppm

11.4 ppm18.2 ppm

54.0 ppm

7/27/2019 YGShul

8/48

Preparation of inorganic particlesin microemulsion

H2O

HPA

Cyclohexane

TEOS

Si(OR)4

+ 4H2O Si(OH)

4+ 4ROH

Si-OH + HO-Si Si-O-Si + H2O

Sol-gel process

O

O

O

O

SO3

-Na

+

Aerosol-OT

7/27/2019 YGShul

9/48

Surface area vs. nano HPA/SiO2

Pore size (A)

0 20 40 60 80

DV/D

R(cm

3/g)

0.00

0.01

0.02

0.03

0.04

0.05

100nm HPA/SiO2

500nm HPA/SiO2Bulk HPA/SiO2

1 2 3

Porefraction

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 2 3 4

BETSurfacearea

(m2/g)

0

100

200

300

400

500

600

Surface area Pore size distribution

HPA 100nm00nmulk

Pore ratio

R > 3nm

100nm00nmulk

R < 1nm

7/27/2019 YGShul

10/48

Application to DMFC

Pressure gauge

Methanol

2M solution.

Fuel pump

Fuel heater

Cell

Needlevalve

flowmeter

2way

valve

O2

Tank

G.C

6 way

valve

Pressure gauge

Methanol

2M solution.

Fuel pump

Fuel heater

Cell

Needlevalve

flowmeter

2way

valve

O2

Tank

G.C

6 way

valve

Heteropolyacid Proton conductivity

Silica particle Methanol blocker

7/27/2019 YGShul

11/48

Polysulfone/nanoparticle compositemembrane

45 50 55 60 65 70 75 80 85 90 95 100 105 1100

20

40

60

80

100

Z''(o

hm)

Z'(ohm)Cell temperature (

oC)

20 40 60 80 100 120 140

Methanolc

rossoverrate

(mol/cm

2m

in)

0

2

4

6

8

10

12

14

16

18

Sulfonated polysulfone membraneComposite membrane

Heteropolyacid-SiO2 nanoparticleHeteropolyacid-SiO2 nanoparticle

1.4 10-3 S/cm 6.510-5 S/cm

Complex impedance response(a) and methanol crossover rate(b) of the sulfonated polysulfone

and sulfonated polysulfone / heteropolyacid SiO2 nanoparticle composite membrane.

(a) (b)

7/27/2019 YGShul

12/48

Nafion/nanoparticle composite membrane

Content of nanoparticles (%)

0 5 10 15 20 25

condu

ctivityx10

2(

S/cm)

0

2

4

6

8

10

Temperature (oC)

0 20 40 60 80 100 120 140 160

Crossove

rrate(mol/cm

2*min)

0

20

40

60

80

100

Nafion membrane

Composite membrane

Proton conductivity(a) and methanol crossover rate(b) of the sulfonated polysulfoneand sulfonated polysulfone / heteropolyacid SiO2 nanoparticle composite membrane.

(a) (b)

Reduction of methanol crossover

A little decrease of proton conductivity

7/27/2019 YGShul

13/48

Nafion-HPA/SiO2 composite membrane

Current density (mA/cm2)

0 50 100 150 200 250 300

Ce

llvo

ltage

(V)

0.0

0.2

0.4

0.6

0.8

80oC

160oC

200oC

Power

dens

ity

(mW/cm

2)

0

10

20

30

40

50

60

Wavenumber (cm-1

)

1000150020002500300035004000

Transmi

ttance

(%)

0

20

40

60

80

100

Heteropolyacid - SiO2

nanoparticle

Sulfonated heteropolyacid - SiO2

nanoparticle

FT-IR spectra of sulfonated heteropolyacid-SiO2 nanoparticle

(Nafion / sulfonated heteropolyacid-SiO2 nanoparticle composite membrane)

H2O H3O+

DMFC performance of composite membrane

Improvement of DMFC performance by increasing the cell temperature

7/27/2019 YGShul

14/48

Research of carbon material application

Caronstructure

FCapplication

Performance remark Reference

Pt/CNT PEMFC 0.7V,

0.7 mA/cm2

(50oC)

high electrocatalytic activity for oxygen reduction

3.60.3nm

J.of powersources

139(2005) 73

Pt/mesoporous carbon

(SBA-15)

DMFC 0.4V,

135 mA/cm2 (65oC)

Great potentiality for DMFC support

Johnson Mattheyat

0.4V, 135 mA/cm2 (80oC)

J.Of powersources

130 (2005)

PtSn/

MWNT

DEFC 0.4V,

100 mA/cm2Improvement in liquid mass transfer for catalyst-

3nm

PtSn/XC-72

0.4V, 80 mA/cm2

Carbon 42

(2004)

Carbon

fiber

Mg-H2O2

Semi-fuelcell

1.5V,

300mA/cm2

Similar reference with Pt-Ir on carbon paper

Mg: anode

Microfiber carbon :cathode

cathode side: 0.20M H2O2

J.Of power

sources 96(2001) 240

Carbonnanocoil

DMFC 0.4V ,

170mA/cm2

(60oC)

Great potentiality for DMFC support material Angew. Chem

2003,115,

4488

Carbonnanohorn

DMFC 0.4V ,

130mA/cm2NEC

7/27/2019 YGShul

15/48

I-V curve for electrodes with commercialPt/C and Pt/C+ Pt/ACF (900)

Current density ( A/cm2

)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4

Vo

ltage(V)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

Commercial Pt/C

Commertial Pt/C (70%)+ Pt/ACF(30%.400oC)

Commertial Pt/C (70%)+ Pt/ACF(30%.900

o

C)

Performance increasing

Commercial Pt/C Pt/C+Pt/ACF (400) Pt/C+Pt/ACF (900)Current density ( mA/cm2 ) 710 807 960

Cell Temp. : 80, Humidify condition : RH% 100 anode and cathode, Flow rate: Stoichiometry 1.5(Anode):2.0(Cathode)

7/27/2019 YGShul

16/48

Impedance for the electrodes manufacturedwith Pt/C, Pt/ACF(900) catalysts

Z' / Ohm

0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26

-Z''/O

hm

0.00

0.02

0.04

0.06

0.08

0.10

Pt/ACF ( 400oC )

Pt/ACF ( 900oC )

Z' / Ohm

0.0 0.1 0.2 0.3 0.4 0.5

-Z''/O

hm

0.00

0.05

0.10

0.15

0.20

0.25

0.30

Pt/ACF ( 400oC )

Pt/ACF ( 900oC )

Impedance spectra at 0.8VImpedance spectra at 0.7V

7/27/2019 YGShul

17/48

Specific surface area and average porediameter of the CNF treated by KOH

58.01303.54950-1h

62.37341.87900-3h

54.41375.52Modified method

44.33460.10900-2h

48.0645.53900-1h48.80509.95800-1h

46.07444.18750-1h

62.21107.60No activation

5H

Avg. Pore diameter( )

Surf. area(m2 /g)ctivation conditionNF

58.01303.54950-1h

62.37341.87900-3h

54.41375.52Modified method

44.33460.10900-2h

48.0645.53900-1h48.80509.95800-1h

46.07444.18750-1h

62.21107.60No activation

5H

Avg. Pore diameter( )

Surf. area(m2 /g)ctivation conditionNF

7/27/2019 YGShul

18/48

SEM - CNFs named 5H

pristine

MDF(900-2h)

800-1h

900-2h

7/27/2019 YGShul

19/48

TEM - 60wt% Pt-Ru/CNF

50 nm 50 nm 50 nm

(a) (b) (c)A/(900-2h) B/(900-2h) B/MDF(900-2h)

7/27/2019 YGShul

20/48

Growth of nanofiber on ACF

micropores

Surface and Pores of

Activated Carbon Fiber

Reduction in He/H2

Synthesis from C2H

4/H2

a

b a, b

c

inactive

H2 C2H4

Impregnation of metal salt solution

7/27/2019 YGShul

21/48

Preparation of various carbon substrates

CNF/ACF

Fig. SEM images of carbon nano fibers grown on ACFFig. SEM images of carbon nano fibers grown on ACFFig. SEM images of carbon nano fibers grown on ACF

7/27/2019 YGShul

22/48

Preparation of platinum on ACF-CNFs

TEM Image of Pt/ACF-CNFs

Fig. TEM images of Platinum oncarbon nanofibers grown on ACF

7/27/2019 YGShul

23/48

Preparation of platinum on ACF-CNFs

XRD patterns of Pt/ACF-CNFs

Fig. XRD pattern of Pt/ACF-CNFs

2 th e ta

3 0 4 0 5 0 6 0 7 0 8 0

Intensity(a.u.)

P t / A C F - C N F s

P t / C ( C o m m e r c ia l )

Pt(1 1 1)

Pt(2 0 0)Pt(2 2 0)

7/27/2019 YGShul

24/48

Single cell performance

Fig. The performance of Pt/ACF-CNFs used in anode catalyst

Cell Temp. : 80, Humidify condition : RH% 100 anode and cathode, Stoichiometry anode: cathode = 1.5: 2.0Membrane : nafion 112:, anode : 20%Pt/C, cathode : 20%Pt/C and 20%Pt/ACF-CNFs+20%Pt/C, Back pressure : 1bar

Current density(A/cm2)

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Vo

ltage

(V)

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Pt/ACF-CNFs 30%

Pt/C

Pt/ACF-CNFs 20%

Pt/ACF-CNFs 100%

7/27/2019 YGShul

25/48

7/27/2019 YGShul

26/48

Schematic Diagram of The ElectrodePrepared by Pulse Electrodeposition

Ion exchange

membrane

Carbon clothe Hydrophobic

carbon layer

Catalystparticle

Reactant gas

Hydrophilic

carbon layer

7/27/2019 YGShul

27/48

Back-Scattered Electron Image and Pt LineScan of The Cross Section of MEA using

EPMA

PC deposition Pt/C layer

membrane

E-TEK Pt/C layer

E-TEK GDL

100.0

0.0

0.0

200.0

161.0Microne

Pt

Distance (m)

PC layer

membraneGDL GDLETEK layer

7/27/2019 YGShul

28/48

ESEM Image and Pt Concentration Profile ofthe Cross Section of MEA Using EDX Spot

Analysis

Distance from membrane (m)

0 2 4 6 8 10 12 14

Ptw

t%

0

20

40

60

80

E-TEK electrode

PC deposition electrode

E-TEK electrode

PC deposition electrode

Membrane

7/27/2019 YGShul

29/48

Comparison of MEA performance betweenpulse electrodeposited electrode and TKK

Current density (A/cm

2

)

0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

Potential(V)

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

TKK (0.4mg/cm2

)PC (0.32mg/cm

2)

7/27/2019 YGShul

30/48

High Throughput Screening (HTS) test

Hydrogen release rate of metal catalysts can bemeasured without catalyst synthesis procedure

To apply metal alloy catalyst, amounts of precursorsolutions can be mixed to accurate ratios.

Schematic diagram of simplified HTS test microreactors

Coolant

Coolant

H2

NaBH4Reduction Hydrolysis

H2Mixed

Precursor

SolutionRuCl3

Co(NO3)2

FeCl2

..

7/27/2019 YGShul

31/48

Hydrogen release test (Ternary alloy)

0

5

10

15

20

25

30

Hydrogen

Ge

nerationRate(Lmin-1g-1)

Ru

Co Ni

0

5

10

15

20

25

30

Hydrogen

GenerationRate(Lmin-1g-1)

Ru

Co Fe

Ru:Co:Fe = 60:20:20

(wt%)

Hydrogen release rate of (a) Ru-Co-Ni, (b) Ru-Co-Fefrom 10 wt% NaBH4 solution with 4 wt% NaOH

(Temperature fixed to 25C)

7/27/2019 YGShul

32/48

XRD Patterns

XRD Patterns of (a) Ru/ACF; (b) NaBH4-reduced

Ru0.6Co0.2Fe0.2/ACF; (c) NaBH4 and H2-reducedRu0.6Co0.2Fe0.2/ACF catalyst

2 theta

30 40 50 60 70

Intensity

RuCoFe

CoFe2O

4

(a)

(b)

(c)

Co and Fe were notreduced completely

when NaBH4 only wasused for reduction. After the additional

reduction by usinghydrogen, CoFe alloywere shown

7/27/2019 YGShul

33/48

RuCoFe/ACF nanocatalyst

1000 / T

3.20 3.25 3.30 3.35 3.40 3.45 3.50

lnk

1.0

1.5

2.0

2.5

3.0

3.5

(a)

(b)

(d)

(e)

(c)

T / oC

10 15 20 25 30 35 40

H2ReleaseRate/Lm

in-1gRu

-1

0

20

40

60

80

100

(a)

(b)

(d)

(e)

(c)

catalyst Reduction

Agent

hydrogen release rate

at 25 C (Lmin-1gRu-1)

Activation Energy

(kJmol-1)

(a)

10 wt% Ru/ACF H2 14.21 59.23

(b)

16 wt% Ru0.6Co0.2Fe0.2/ACF H2 22.63 47.91

(c) 16 wt% Ru0.6Co0.2Fe0.2/ACF NaBH4 34.37 50.54

(d)

13 wt% Ru0.75Co0.25/ACF NaBH4 + H2 37.12 45.44

(e 16 wt% Ru0.6Co0.2Fe0.2/ACF NaBH4 + H2 41.73 44.01

7/27/2019 YGShul

34/48

Conclusions

Nano materials may lead to drastic improvement in fuel cellapplication

1)Nanohybride electrolyte (HPA-SiO2+Nafion) waseffective for the high temperature operating of DMFC

2)New nano carbons are promising to enhance the catalytic

activity in fuel cell3) Nano alloy will be effective to release control of the H2from chemical hydride (NaBH4, NH3BH3)

4) Electrodeposition is effective to reduce the amount of Ptloading

7/27/2019 YGShul

35/48

Acknowledgement

7/27/2019 YGShul

36/48

Backup slides

7/27/2019 YGShul

37/48

Impedance spectra

Fig. Impedance spectra of single cell

Z'/Ohm

0.05 0.10 0.15 0.20 0.25

-Z''/Ohm

0.00

0.02

0.04

0.06

0.08

0.10

Pt/ACF-CNFs 30%

Pt/C

Pt/ACF-CNFs 20%

Pt/ACF-CNFs 100% Membrane resistance 0.063

Interfacial resistance

(Mixture ratio 20%Pt/C:20%Pt/ACF-CNFs)

Only 20% Pt/C 0.069

Only 20% Pt/ACF-CNFs 0.175

2:8 0.096

3:7 0.065

7/27/2019 YGShul

38/48

Cyclic voltammogram

E /V

-0.2 0.0 0.2 0.4 0.6 0 .8 1.0 1.2

i/A

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

Pt/C

Pt /ACF -CNT s 30%

Fig. Cyclic voltammograms of Pt/ACF-CNFs used oxygen

7/27/2019 YGShul

39/48

Technical Barriers of Electrodes for PEMFuel Cells

Electrode performance 400 mA/cm2 at 0.8V with H

2

/Air and 1atm

Novel method of pulse electrodeposition

Pt-X alloy

Material Cost 0.2 g (Pt loading)/peak kW Non-precious catalyst (Pt-free)

Durability 40,000 hours operation with

7/27/2019 YGShul

40/48

Why Pulse Electrodeposition(Dependence of Nucleation Rate on

Overpotential)

2

1 expbs

J KzekT

=

log i = +

K1 - rate constant

S - surface area occupied by oneatom on the surface of the nucleus

e - the charge of the electron

z - the electronic charge of the ion

k - the Boltzmann constant

T- the temperature b=P2/4S, where P is the perimeter and

S is the surface area

i current applied

, Tafel constants Overpotential 1: on time 2: off time Ip: peak current density

Ia: average current density

Duty cycle: 1/

Rate of 2D-nucleation * Tafel expression for overpotential

1 2

t5t4t3t2t1

Current

density

time

ip

ia

Pulse electrodeposition

Off time

Concentration of electrolyte is recoveredElectrodeposition at high current density

7/27/2019 YGShul

41/48

Comparison of the Limiting Current Densitybetween Pulse and Direct Electrodeposition

diffusion model by H. Y. Cheh,

( )( )

l

dc l

i

i

a

0.4

1 0.2

=

0.6

0.8

1.0

a( )( )

( )( )( )( )( )

2

2

22 21

1

exp 2 1 18 11

2 1 exp 2 1 1

p l

dc l

j

i

i j a

j j a

=

=

2 2 1/ 4 (sec )D a =

7/27/2019 YGShul

42/48

TEM and SEM image of Pt electrodepositedelectrodes

Pulse DC

7/27/2019 YGShul

43/48

Polarization Curves of MEAs Prepared byDirect Current and Pulse Electrodeposition

Current density (A/cm2)

0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4

Po

ten

tia

l(V)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

50mA/cm2

DC

200mA/cm2

PC

The conditions of pulse electrodeposition: 200mA/cm2 of peak current density,

5.2ms on time and 70ms off time. Total charge is fixed at 6C/cm

2

on both cases.

Nafion 112

Cell Temperature: 75 oC

H2/O2 (flow rate: 1.5/2 stoichiometric)

Pressure: 1atm

SEM Images of Pt Electrodeposited

7/27/2019 YGShul

44/48

SEM Images of Pt ElectrodepositedElectrodes by D.C or P.C mode. (Total

charge is fixed at 6C/cm2 on both cases)

50mA/cm2

of D.C. electrodeposition 200mA/cm2

of peak current density,5.2ms on time and 70ms off time

Effect of the peak current density of pulse

7/27/2019 YGShul

45/48

Effect of the peak current density of pulseelectrodeposition on the performance of the

PEM fuel cell


0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

Po

ten

tia

l(V)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

10 mA/cm2

DC

30 mA/cm2

PC

100 mA/cm2 PC

200 mA/cm2

PC

400 mA/cm2

PC

600 mA/cm2

PC

Cyclic Voltammograms of the Electrodes

7/27/2019 YGShul

46/48

Cyclic Voltammograms of the ElectrodesPrepared at Different Peak Current

Densities in Pulse Electrodeposition

Potential (V. Hg/Hg2SO

4)

-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8

Curren

tdens

ity

(mA/cm

2)

-1.5

-1.0

-0.5

0.0

0.5

1.0

200mA/cm2

100mA/cm2

400mA/cm2

30mA/cm2

600mA/cm2

7/27/2019 YGShul

47/48

Effect of Charge Density on thePerformance of PEM Fuel Cell


0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0

Potential(V)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

6C/cm2

8C/cm2

13C/cm2

16C/cm2

Comparison of Pt line scan image in the

7/27/2019 YGShul

48/48

Comparison of Pt line scan image in thecross section of the MEA

(A) 8C/cm2 and (B) 20C/cm2

Microns (m)

Cps Cps

300 300

0

0 0

0

40 40

Microns (m)

(A) (B)

Microns (m)

Cps Cps

300 300

0

0 0

0

40 40

Microns (m)

(A) (B)

Documents

YGShul