Past, Present, and Future Challenges in Electrocatalysis for Fuel ...
Transcript of Past, Present, and Future Challenges in Electrocatalysis for Fuel ...
1 | Fuel Cell Technologies Office eere.energy.gov
FCTO Monthly Webinar Series:
Past, Present and Future Challenges in Electrocatalysis for Fuel Cells
U.S. Department of Energy Fuel Cell Technologies Office October 13th, 2016
Presenter: Voya (Vojislav) Stamenkovic Argonne National Laboratory
DOE Host: Dimitrios Papageorgopoulos Fuel Cell Technologies Office
2 | Fuel Cell Technologies Office eere.energy.gov
Question and Answer
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M a t e r i a l s S c i e n c e D i v i s i o n A r g o n n e N a t i o n a l Laboratory
DOE EERE Fuel Cell Technology Office Webinar Series October 13, 2016
Past, Present and Future Challenges in Electrocatalysis for Fuel Cells
Vojislav Stamenkovic
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’60s
’60-70s
’80-2011
PEM FC unsupported Pt catalyst loading: 28 mgPt/cm2 membrane: Nafion T ~ 21oC
Alkaline FC Ni based catalyst T ~ 250oC Operating time: 400-690h
Alkaline FC Pt and PtAu catalysts loading: 10 and 20 mgPt/cm2 T ~ 93oC Operating time: > 16 days
cubo-octahedral particles
30 nm (Pt/C) 10 % Pt/Vulcan 3 nm
Particle Size Effect
5
ORR: cathode limitations
Main limitations in PEM fuel cell technology:
2) Durability: (Pt catalyst dissolves) 3) Pt loading: Cost Issues
1) Activity: Pt/C = Pt-poly/10
losses ~ 30-40% (!!!) Cathode kinetics (?!)
2020 DOE Technical Targets
• Durability w/cycling (80oC): 5000 hrs
• Mass activity @0.9V: 0.44 A/mgPt
• PGM Total content: 0.125 g/kW
• Electrochemical area loss: < 40%
• PGM Total loading: 0.125 mg/cm2 electrode
7
Activity | Durability | Cost
3o Surface Modifications
1o Structure-Function
4o Tailored Electrolytes
Specific/Mass Activity Electrochemical Stability Loading
2o Composition-Function
(c)As prepared
As prepared
(a) (b)
Curr
ent D
ensi
ty (a
. u.)
STM: Pt Single Crystals
Pt(111) Pt(100)
Pt(110)
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0.925 V 0.900 V 0.875 V 0.850 V
Kin
etic
Cur
rent
Den
sity
[mA
/cm
^2]
Pt(110)Pt(111)Pt(100)Series4Pt-poly average
9
Dissolved Pt per cycle [µML]
Pt Surface
Total Pt loss over one potential cycle up to 1.05 V for distinct Pt surface morphologies, indicating the stability trend follows the coordination number of the surface sites
Pt(111) 2
Pt(100) 7
Pt(110) 83
Pt-poly 36
Pt/C | 103*
Quadrupole mass filter
Horizontal torch
Electrochemical Cell
P. P. Lopes, D. Strmcnik, J. Connell, V. R. Stamenkovic and N.M. Markovic ACS Catalysis, 6 (4), 2536-2544, 2016
In-Situ EC-ICP-MS Pt(hkl)-Surfaces vs. Pt/C
10
[011]
[01-1]
(110)-(1x1)
p(1x1)
Pt3Ni(110)
(e) Pt3Ni(100)
c(5x1)
(f)
Pt3Ni(111)(d)
[1-1
0]
[001]
LEED
Surface Structure + Composition: Pt3Ni[hkl] Surfaces
Sputtered
Annealed
STM
LEIS
11
Activity: ORR Platinum Alloy Surfaces
Pt3Ni(110) Pt3Ni(100)
Pt(hkl)
Pt3Ni(111)
Pt3Ni(hkl)
0.1 M HClO4
Pt3Ni(hkl)
(110) (111) (100)
Pt (111)
0.1 M HClO4 0.95 V vs. RHE 20 °C
Pt3Ni(hkl)
Pt3Ni(111)/Pt-Skin Surface is the most active catalyst for the ORR
Science, 315 (2007) 493 12
60
E [V] vs. RHE0.0 0.2 0.4 0.6 0.8 1.0
Inte
nsit
y [a
rb. u
nits
]
6.0
6.5
7.0
1 2 3 4 5 6 7
Pt [a
t. %
]
0
20
40
60
80
100
100
80
60
20
0
40
Pt [
at. %
]
Ni [
at. %
]
Atomic layer
SXS
(b)
(a)
(a’)
Θ
Hup
d [%
]
60
30
0
60
30
0
ΘO
xd [
%]
i [µ
A/c
m2 ]
60
30
0
-60
-30
Pt3Ni(111)
Pt(111)
y
CV
(c)
E [V] vs. RHE0.0 0.2 0.4 0.6 0.8 1.0
i [m
A/c
m2 ]
-6
-4
-2
0
I II III
H2O
2 [%
]
Pt poly
050
ORR
(d)
∆E~100 mV
Subsurface Composition + Surface Structure: Pt3Ni(111)
Science, 315(2007)493
Pt3Ni(111)/Pt-Skin Surface is the most active catalyst for the ORR (100-fold enhancement)
13
60
E [V] vs. RHE0.0 0.2 0.4 0.6 0.8 1.0
Inte
nsit
y [a
rb. u
nits
]
6.0
6.5
7.0
1 2 3 4 5 6 7
Pt [a
t. %
]
0
20
40
60
80
100
100
80
60
20
0
40
Pt [
at. %
]
Ni [
at. %
]
Atomic layer
SXS
(b)
(a)
(a’)
Θ
Hup
d [%
]
60
30
0
60
30
0
ΘO
xd [
%]
i [µ
A/c
m2 ]
60
30
0
-60
-30
Pt3Ni(111)
Pt(111)
y
CV
(c)
E [V] vs. RHE0.0 0.2 0.4 0.6 0.8 1.0
i [m
A/c
m2 ]
-6
-4
-2
0
I II III
H2O
2 [%
]
Pt poly
050
ORR
(d)
∆E~100 mV
Subsurface Composition + Surface Structure: Pt3Ni(111)
Science, 315(2007)493
Pt3Ni(111)/Pt-Skin Surface is the most active catalyst for the ORR (100-fold enhancement)
13
Controlled Synthesis: Multimetallic Nanocatalysts
Colloidal solvo - thermal approach has been developed for monodispersed PtM NPs with controlled size and composition
Efficient surfactant removal method does not change the catalyst properties
Controlled Synthesis: Multimetallic Nanocatalysts
Colloidal solvo - thermal approach has been developed for monodispersed PtM NPs with controlled size and composition
Efficient surfactant removal method does not change the catalyst properties
4o Surface chemistry of homogeneous Pt-bimetallic NPs PtxM(1-x) NPs
Dissolution of non Pt atoms forms Pt-skeleton surface
3o Composition effect in Pt-bimetallic NPs Pt3M
Optimal composition of Pt-bimetallic NPs is PtM 1 nm
0.22 nm
1 nm1 nm
PtM PtM2 PtM3
1o Particle size effect applies to Pt-bimetallic NPs Specific Activity increases with particle size: 3 < 4.5 < 6 < 9nm
Mass Activity decreases with particle size
Optimal size particle size ~5nm J. Phys. Chem. C., 113(2009)19365
2o Temperature induced segregation in Pt-bimetallic NPs Agglomeration prevented
Optimized annealing temperature 400-500oC
(b)
Phys.Chem.Chem.Phys., 12(2010)6933
Adv. Funct. Mat., 21(2011)147
HAADF - STEM
1 2 3 4 5 6 7 8 9 100
20
40
60
80
100davg = 5.9 nm
Coun
tsSize (nm)
Particle size distribution
PtM Alloy NPs | Distribution: Elements and Particle Size
ACS Catalysis, 1 (2011) 1355 14
Controlled Synthesis: Multimetallic Nanocatalysts
Colloidal solvo - thermal approach has been developed for monodispersed PtM NPs with controlled size and composition
Efficient surfactant removal method does not change the catalyst properties
4o Surface chemistry of homogeneous Pt-bimetallic NPs PtxM(1-x) NPs
Dissolution of non Pt atoms forms Pt-skeleton surface
3o Composition effect in Pt-bimetallic NPs Pt3M
Optimal composition of Pt-bimetallic NPs is PtM 1 nm
0.22 nm
1 nm1 nm
PtM PtM2 PtM3
1o Particle size effect applies to Pt-bimetallic NPs Specific Activity increases with particle size: 3 < 4.5 < 6 < 9nm
Mass Activity decreases with particle size
Optimal size particle size ~5nm J. Phys. Chem. C., 113(2009)19365
2o Temperature induced segregation in Pt-bimetallic NPs Agglomeration prevented
Optimized annealing temperature 400-500oC
(b)
Phys.Chem.Chem.Phys., 12(2010)6933
Adv. Funct. Mat., 21(2011)147
PtxNi1-x: Surface Chemistry and Composition Effect
15 Adv. Funct. Mat., 21 (2011) 14715
PtxNi1-x: Surface Chemistry and Composition Effect
15 Adv. Funct. Mat., 21 (2011) 14715
As-prepared PtNi
Inte
nsity
(a. u
.)
Position (nm)43 5210
Position (nm)43 5210
Inte
nsity
(a. u
.)
Pt Ni
400oC
Temperature annealing protocol used to transform PtNi1-x skeletons to multilayered PtNi/Pt NPs with 2-3 atomic layers thick Pt-Skin
PtNi1-y Skeleton
HRTEM
Line profile
PtNi/Pt core/shell
PtNi with multilayered Pt-Skin Surfaces : Tailoring Nanoscale Surfaces
16
Catalysts with multilayered Pt-skin surfaces exhibit substantially lower coverage by Hupd vs. Pt/C
(up to 40% lower Hupd region is obtained on Pt-Skin catalyst)
Electrooxidation of adsorbed CO (CO stripping) has to be performed for Pt-alloy catalysts in order to avoid underestimation electrochemically active surface area and overestimation of specific and mass activities
Surface coverage of adsorbed CO is not affected on Pt-skin surfaces
As Synthesized Leached Annealed
∆
Multilayered Pt-skin NP
Ratio between QCO/QHupd>1 is indication of Pt-skin formation
TEM
Pt-NPs PtNi-NPs
davg = 5 nm
Catalyst QH (µC)
ECSAH (cm2)
QCO (µC)
ECSACO (cm2)
QCO/2QH
Pt/C 279 1.47 545 1.41 0.98 PtNi/C 292 1.54 615 1.60 1.05
PtNi-skin/C 210 1.10 595 1.54 1.42
NPs with multilayered Pt-Skin Surface: PtNi/C
17
-0.1
0.0
0.1
0.0 0.2 0.4 0.6 0.8 1.0
6 nm Pt/C acid treated PtNi/C acid treated/annealed PtNi/C
E (V vs. RHE)
i (m
A/cm
2 Pt)
0.6 0.7 0.8 0.9 1.0
-6
-4
-2
0
E (V vs. RHE)
i (m
A/cm
2 geo)
0.1 10.90
0.95
1.00
E (V
vs.
RHE
)jk (mA/cm2)
8320 8340 8360 8380 8400
0.0
0.5
1.0
1.5
acid treated acid treated/annealed Ni NiO
Norm
aliz
ed A
bsor
ptio
n µ(
E)
E (eV)
Ni K at 1.0 V
11540 11560 11580 11600 11620
0.0
0.5
1.0
1.5
acid treated acid treated/annealed Pt
Norm
aliz
ed A
bsor
ptio
n µ(
E)
E (eV)
Pt L3 at 1.0 V
a
b
c
ed
RDE: PtNi-Skin catalyst exhibits superior catalytic performance for the ORR and is highly durable system
TEM/XRD: Content of Ni is maximized and allows formation of the multilayered Pt-skin by leaching/annealing
In-Situ XANES: Subsurface Ni is well protected by less oxophilic multilayered Pt-skin during potential cycling
PtNi Catalyst: RDE Studies of Multilayered Pt-Skin Surfaces
0.0
0.2
0.4
0.6
0.8
1.0 before
Spec
ific
Act
ivity
(mA
/cm
2 )
after
0
2
4
6
Impr
ovem
ent F
acto
r(v
s. P
t/C)
0
2
4
6
8
10
after before
Durability: Surface area loss about 10%, SA 8 fold increase and MA 10 fold increase over Pt/C after 20K cycles
PtNi/C Pt/C PtNi/C Skin
18
Skeleton
J. Amer. Chem. Soc. 133 (2011) 14396
- H2PtCl6 and Ni(NO3)2 react in oleylamine at 270oC for 3 min forming solid PtNi3 polyhedral NPs
- Reacting solution is exposed to O2 that induces spontaneous corrosion of Ni - Ni rich NPs are converted into Pt3Ni nanoframes with Pt-skeleton type of surfaces
- Controlled annealing induces Pt-Skin formation on nanoframe surfaces
Science , 343 (2014) 1339
Mass Activity Enhancement by 3D Surfaces: Multimetallic Nanoframes
In collaboration with Peidong Yang, UC Berkeley
20
- Narrow particle size distribution
- Hollow interior
- Formation of Pt-skin with the thickness of 2ML
- Surfaces with 3D accessibility for reactants
- Segregated compositional profile with overall Pt3Ni composition
Science , 343 (2014) 1339
Compositional Profile: PtNi Nanoframes with Pt-skin Surfaces
21
Multimetallic Nanoframes with 3D Electrocatalytic Surfaces
Science , 343 (2014) 1339 22
Improving the ORR Rate by Protic Ionic Liquids
Erlebacher and Snyder, Advanced Functional Materials, 23(2013)5494
[MTBD][beti]
2
2 4
,[MTBD][ ]
O ,HClO
2.40 0.013O betiCC
= ±Pt/C np-NiPt/C np-NiPt/C+IL
0.95 V vs. RHE
Chemically Tailored Interface High O2 solubility along with hydrophobicity yield improved ORR kinetics
23
C - No change in activity after 10K cycles 0.6 – 1.0 V
- Mass activity increase over 35-fold vs. Pt/C
- Specific activity increase over 20-fold vs. Pt/C
- Increase in mass activity over 15-fold vs. DOE target
Science , 343 (2014) 1339
RDE @ 0.95V vs. RHE 0.1M HClO4 1600 rpm
RDE @ 0.90V vs. RHE 0.1M HClO4 1600 rpm
Tailoring Activity: PtNi Nanoframes as the ORR Electrocatalyst
24
Initial morphology
DURABILITY: Pt/C
After 60,000 cycles Potential Range: 0.6-1.0V
25
• Commercial catalysts are usually made by impregnation methods.
• Poor control – Broad size distribution – Different, undefined
morphologies, but everyone calls them “cubo-octahedral”, which is, in fact, not correct!
c d e
Commercial Pt/C Catalysts
26
Initial morphology
DURABILITY: Pt/C
After 60,000 cycles Potential Range: 0.6-1.0V
27
Initial morphology
DURABILITY: Pt/C
After 60,000 cycles Potential Range: 0.6-1.0V
27
SIZE EFFECT(s)? Pt/C
28
20 nm
cubo-octahedron truncated cube cube
• Uniform morphology • Size control octahedron (?) cubo-octahedral Cube
SHAPE EFFECT(s)? Pt/C
29
3 nm
2) Size distribution: 2-15 nm
1) Shape: cubooctahedron
3) Composition: Pt, C
4) Side Orientation: [111], [100]
HR-TEM: Characterization of Nanoscale Pt/C Catalyst
x 15
x 5
30
0.0 0.2 0.4 0.6 0.8 1.0
-0.08
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
i [m
A/cm
2 ]
E [V vs RHE]0.0 0.2 0.4 0.6
-2.0x10-4
0.0
2.0x10-4
I/AE/V vs. RHE
[001]
(100)
(111)
APPROACH: Well-Defined Systems (ext & nano)
31
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0.925 V 0.900 V 0.875 V 0.850 V
Kin
etic
Cur
rent
Den
sity
[mA
/cm
^2]
Pt(110)Pt(111)Pt(100)Series4Pt-poly average
Detector
Quadrupole
Quadrupole allows single m/z pass at any given time Time frame for the range of m/z = 1 – 240 is 0.1sec
Quadrupole mass filter
Horizontal torch
ICP-MS: Principle of Operation
32
RDE/ICP-MS: Pt(hkl)
Rotating Disk Electrode
333
Standard Deviation σ=(Σ(µ-xi)2/n-1)1/2
λ (amu)
DL=3σbckg(λ)
Background
Method detection limit (DL) is applied to blank sample prepared
with all analytical steps related to given methodology, since each
step is potential error source
Limit of quantification (LOQ) is 3 times DL
Dissolved Pt per cycle [µML]
Pt Surface
Total Pt loss over one potential cycle up to 1.05 V for distinct Pt surface morphologies, indicating the stability trend follows the coordination number of the surface sites
Pt(111) 2
Pt(100) 7
Pt(110) 83
Pt-poly 36
Pt/C | 103*
In-Situ RDE / ICP-MS: Pt(hkl)-Surfaces vs. Pt/C
34
Pt/C | 103*
GC-Pt(4ML)
GC-Au-Pt(4ML)
In-Situ RDE / ICP-MS: Pt/C, Pt and Pt/Au Well-Defined Surfaces
35
DURABLE NPs: Core-Interlayer-Shell Particles
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
-6-5-4-3-2-101234
i (m
A cm
-2)
E (V vs RHE)I want this blanked out!
I would love this area to blank outI would love this area to blank outI would love this area to blank outI would love this area to blank out
-80
-40
0
40
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
I (µA
cm
-2)
E (V vs RHE)
0
2
4
6
8
Au(111
)-Pt
3
2
Au(111
)-FeP
t 3
FePt 3
-poly
Pt-p
oly
1
Impr
ovem
ent F
acto
r vs
Pt P
oly
Spe
cific
Act
ivity
(iki
n/ m
Acm
-2)
Hupd
x 3
I II III IV
double layer Pt-OHad Au-OHad
Au(111)Au(111)-PtAu(111)-FePt3
A
ORR @ 0.9V
B
C
Nano Letters, 11 (2011) 919
NiPt3
36
DURABLE NPs: Core-Interlayer-Shell Particles
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
-6-5-4-3-2-101234
i (m
A cm
-2)
E (V vs RHE)I want this blanked out!
I would love this area to blank outI would love this area to blank outI would love this area to blank outI would love this area to blank out
-80
-40
0
40
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
I (µA
cm
-2)
E (V vs RHE)
0
2
4
6
8
Au(111
)-Pt
3
2
Au(111
)-FeP
t 3
FePt 3
-poly
Pt-p
oly
1
Impr
ovem
ent F
acto
r vs
Pt P
oly
Spe
cific
Act
ivity
(iki
n/ m
Acm
-2)
Hupd
x 3
I II III IV
double layer Pt-OHad Au-OHad
Au(111)Au(111)-PtAu(111)-FePt3
A
ORR @ 0.9V
B
C
Nano Letters, 11 (2011) 919
NiPt3
36
4nm
~ 5-6nm
Ni core
Au interlayer
PtNi shell 2 nm 2 nm
Monodisperse , Core/Interlayer/Shell NPs: Ni core / Au interlayer / PtNi shell
Compositional Profile: Core/Interlayer/Shell Electrocatalysts
37
Durable ORR Catalysts: Core/Shell NPs with Au Interlayer
- Pt - Au
segregation trend of Au onto surfacedriving force that diffuses Pt into the bulkdriving force induced by strong Pt - OHad interaction
- O
segregation trend of Pt into the bulk
- Fe- Ni
Stabilization mechanism
38 Nano Letters, 14 (2014) 6361
Nanoframes in 5cm2 MEA ANL and ORNL
Durable Systems: PtNi Nanoframes in MEA
Cathode Loading: 0.035 mg-Pt/cm2, I/C = 0.8 H2/O2, 80°C, 150 kPa(abs), 100%RH
ORR Activity @ 0.9V: Mass Activity x3.5 Specific Activity x6.5 TKK 20 wt%Pt/C: 0.22 A/mg-Pt 0.39 mA/cm2-Pt
PtNi Nanoframes: 0.76 A/mg-Pt 2.60 mA/cm2-Pt
in collaboration with Debbie Myers, ANL - CSE
39
Nanoframes in 5cm2 MEA ANL and ORNL
Durable Systems: PtNi Nanoframes (before and after)
0.1 µm
HAADF-STEM
0.1 µm
BF-STEM
membraneca
taly
st la
yer
membrane
5 nm
BF-STEM Pt Ni
5 nm
40
in collaboration with Debbie Myers, ANL - CSE
Cathode Loading: 0.046 mg-Pt/cm2 I/C = 1, H2/O2 (or Air), 80°C, 150 kPa(abs), 100%RH
0 500 1000 1500 2000 2500 30000.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
H2/O2 Performance
Commercial TKK Pt/C PtNi/C
IR c
orre
cted
Cel
l Vol
tage
(V)
Current Density (mA/cm2)0 300 600 900 1200 1500 1800
0.2
0.4
0.6
0.8
1.0
H2/Air Performance
Commercial TKK Pt/C PtNi/C
Cel
l Vol
tage
with
out I
R co
mpe
nsat
ion
(V)
Current Density (mA/cm2)
Units PtNi TKK Pt
Pt loading mgPGM/cm²geo 0.045 0.045
Mass Activity (H2-O2)
A/mgPGM @ 0.9 ViR-free
0.60 0.27
Specific Activity (H2-O2)
mA/cm2PGM
@ 0.9 ViR-free 1.85 0.39
MEA performance (H2-Air)
mA/cm2
@ 0.8 V 101 47
ECSA m2/gPGM 35.10 52.5
TKK 20 wt%Pt/C PtNi 16.7 wt%Pt/C
Durable Systems: PtNi with Multilayered Pt-Skin Surfaces
41
TM doped Pt3Ni Octahedra
Huang et al. Science , 348 (2015) 1230 SA and MA over 70-fold vs. Pt/C
Bu et al. Nat. Commun. , (2016) DOI 10.1038.natcomms11850
Hierachical PtCo Nanowires
SA and MA over 30-fold vs. Pt/C
Dealloying of PtNi octahedrons
Cui et al. Nature Mat., 12 (2013) 765 SA and MA over 10-fold vs. Pt/C
Alloying Pt with Rare Earth Elements
Escudero-Escribano et al. Science, 352 (2013) 73
SA over 6-fold vs. Pt/C
Greeley et al. Nature Chem., 1 (2009) 552
Pt/CuNW and PtNT
Alia et al. ACS Catalysis., 3 (2013) 358 SA and MA over 3-fold vs. Pt/C
Pt/CuNW
PtNT
BNL: Electrocatalyst Development
Remaining Challenges and Barriers
1) Durability of fuel cell stack (<40% activity loss)
2) Cost (total loading of PGM 0.125 mgPGM / cm2)
3) Performance (mass activity @ 0.9V 0.44 A/mgPt)
• Differences between RDE and MEA, surface chemistry, ionomer catalyst interactions
• Temperature effect on performance activity/durability
• High current density region needs improvements for MEA
• Support – catalyst interactions
• Scale-up process for the most advanced structures
Pt(hkl) with Ionomer
2x refers to the case of 10 µl of solution (0.005% wt.) applied to the electrode. Thickness can then be calculated by using a dry density of 1.5 g/cm3
49
Strongly Adsorbing Electrolytes: Improving the ORR Rate E [V vs. RHE]
0.0 0.2 0.4 0.6 0.8 1.0
Cur
rent
den
sity
[mA/
cm2 ]
-100
-50
0
50
100
Pt (111) - O2
- SO4 / PO4 2- 3-
Cyanide adlayer forms (2√3x 2√3)R30o structure on Pt (111) Itaya et al. J.Am.Chem.Soc. 118 (1996) 393
E [V vs. RHE]0.0 0.2 0.4 0.6 0.8 1.0
Cur
rent
den
sity
[mA/
cm2 ]
-6
-5
-4
-3
-2
-1
0
Pt (111)
- O2 - CN-
- SO4 / PO4 2- 3- Cyanides prevent the adsorption of sulfates/phosphates
~200 mV enhancement in the ORR
Nature Chemistry, 2 (2010) 880 50
57 2016 ECS Spring Meeting
Pt/HSAC Pt/Vulcan Pt/LSAC
• highly disordered with meso-graphitic outer ‘shell’ • Pt “inside” carbon particles
• concentric ‘domain’ structure ~4-5 nm graphite domain size
• Pt on surface of carbon particles
• highly ordered/faceted graphitic ‘shell’ with hollow
core • poor Pt surface dispersion
< <
Carbon Supports for Fuel Cell Catalysts
4nm 4nm 4nm
58 2016 ECS Spring Meeting
Imaging Catalyst Distributions in 3D
reconstructed volume (z-stack)
aligned HAADF tilt series
segmentation, visualization, and quantitative analysis
50 nm
50 nm
50 nm
• Quantify initial catalyst dispersions on different
carbon supports agglomeration • Elucidate catalyst degradation mechanisms (Pt agglomeration, coarsening, dissolution) AST for catalyst degradation 30,000 cycles 0.6-1.0V
• Improve stability and durability of
catalyst/support through structural optimization
SE HAADF STEM/EDS
59 2016 ECS Spring Meeting
Technical Accomplishments and Progress: Imaging Ionomer Dispersions in Catalyst Layers in 3D
17 MEA slices
Individual F maps acquired from “slices” are stacked to create a 3D rendering/reconstruction of the ionomer distribution within a given volume of the CL
1 µm
60 2016 ECS Spring Meeting
1 µm
200 nm
200 nm
single ~ 300 nm pore
Same pore with ionomer
200 nm
Technical Accomplishments and Progress: Imaging Ionomer Dispersions in Catalyst Layers in 3D
To correlate ionomer with porosity (and
simplify visualization), a single secondary pore
is selected from CL volume using
corresponding STEM images
Collaborations
Low-PGM Alloy Catalysts
Low-PGM Alloys
Advanced Catalyst Supports
Sub: synthesis, scale-up support Lead: design, synthesis, evaluation
Sub: catalyst supports Sub: structural characterization
Catalysts Scale Up
Lead: process R&D and scale-up
Sub: process support
MEA
Lead: 5 and 25cm2 MEA
Sub: 25 and 50cm2 MEA
OEMs
T2M
55
Collaborations
Single Crystals
Solid Nanoparticles
NPs with Skin Surfaces
Core-Shell NanoparticlesShaped Particles
Meso-S Thin FIlms
Nanoframes and Nanowires
H2O
H2
O2
A
anode
PEM
anode
H+ H+ H+ H+
H+
cathode
H+
Thin Films
55
RDE
MEA
Toyota - Mirai
A P P R O A C H
Full time postdocs:
Grad student: Nigel Becknell (synthesis, RDE, EXAFS)
Dongguo Li (RDE, synthesis, thin films) Haifeng Lv (RDE, synthesis, MEA) Rongyue Wang (scale up syntehsis, RDE, MEA)
Partial time postdocs: Pietro Papa Lopes (RDE-ICP-MS)
Partial time Staff: Paul Paulikas (UHV, thin films) Dusan Strmcnik
Collaborators: Guofeng Wang, University of Pittsburgh Jeff Greeley, Purdue University Plamen Atanassov, University of New Mexico Debbie Myers, Argonne National Laboratory Rod Borup, Los Alamos National Laboratory Karren More, Oak Ridge National Laboratory Peidong Yang, University of California Berkeley
Principal Investigators: Vojislav Stamenkovic Nenad Markovic
This research was supported by the Office of Science, Basic Energy Sciences, Materials Sciences Division and the Office of Energy Efficiency and
Renewable Energy of the U.S. Department of Energy
Chao Wang, ANL (Johns Hopkins University)
Dennis van der Vliet, ANL (3M)
Ramachandran Subaraman, ANL (Bosch Research Center)
Yijin Kang, ANL (UESR)
Nemanja Danilovic, ANL (ProtonOnSite)
Acknowledgments
Fuel Cell Technologies Office | 65
Thank you
hydrogenandfuelcells.energy.gov
Dimitrios Papageorgopoulos Program Manager – Fuel Cells
DOE Fuel Cell Technologies Office
Voya (Vojislav) Stamenkovic Argonne National Laboratory