RECENT DEVELOPMENTS IN PGM-FREE &
ULTRALOW PT CATALYSTS AT ARGONNE
Di-Jia Liu
Chemical Sciences & Engineering DivisionArgonne National Laboratory, USA
Presented at 2017 Spring Annex 31/35 Meeting “HIGHLIGHTS OF INTERNATIONAL FUEL CELL RESEARCH 2017”, Graz, Austria, May 15-16, 2017
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Argonne National Laboratory – A Primer DOE Facility on
Energy, Environment & National Security Research
Founded in 1943, designated a National Laboratory in 1946 (nation’s first)
Multi-discipline, multi-program
– 3300 employees, 1600 Scientists/Engineers, 300 Postdocs
– $780 million annual budget
Broad-based R&D in basic science, energy resources, environmental management, and national security
Major user facilities
– Advanced Photon Source (APS)
– Argonne Tandem Linear Accelerator System (ATLAS)
– Center for Nanoscale Materials (CNM)
– Argonne Leadership Computing Facility (ALCF)
– Transportation Research & Analysis Computing Center (TRACC)
Located on 1500 wooded acres,25 miles southwest of Chicago’s Loop
Argonne National Laboratory – Major User Facilities
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Advanced Photon Source
Energy Science Building
Nano Material Research Center
Argonne Leadership Computing
Facility (ALCF)
US DOE FCTO Overview
MissionTo enable the widespread commercialization of hydrogen and fuel cell technologies through basic and applied research, technology development and demonstration, and diverse efforts to overcome institutional and market challenges.
Impact
2-4 million barrels/daypetroleum reduction by 2050
200- 450 million metric tons/year GHG emissions reduction by 2050
Strategy and Approach 2020 Targets
Fuel Cell Cost
Durability
H2 Cost at Pump
$40/kW
5,000 h 80,000 h
$1,000/kW*$1,500/kW**
<$4/gge
$10/kWhH2 Storage Cost (On-Board)
*For Natural Gas**For Biogas
U S DOE Fuel Cells & H2 Strategy
Reducing platinum usage to < 0.125 g/kW (or 10 g/vehicle at 80 kW rated power)
Increasing MEA durability to 5000 hours under cycling
Increasing stack power density to 0.85kW/L (or stack volume of 94L for 80kW unit)
Reducing costs of accessories, bipolar plates, air compressor, humidification, etc.
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High
Medium
Low to Medium
Level of
Difficulty
BARRIERS NEAR TO MID-TERM LONG-TERM
700 bar tanks, composites, cryo-
compressedHydrogen Production and Delivery
Materials R&D for low pressure
storage
Non-PGM Catalysts
AEMs
Fuel Cell Cost and Durability
Hydrogen Storage
R&
D
Low-PGM catalysts , MEAs, performance
durability, components
H2 from NG/electrolysis; delivered H2, compression
H2 from renewables (PEC, biological, etc.),
pipelines, low P option
Near and mid-term research focuses
Replacing the platinum group metal (PGM) catalysts with earthly abundant materials
Improving ion conductivity and stability of alkaline electrolyte membranes
Long-term research focuses
• Strategic technical analysis guides focus areas
for R&D and priorities.
• Need to reduce cost to $30/kW and increase
durability from 2,500 to 5,000 hours.
• Advances in PEMFC materials and components
could benefit a range of applications
Strategies to Address Challenges
Catalyst Examples
●Lower PGM Content
●Pt Alloys
●Novel Support Structures
●PGM-free catalystsPEMFC Stack Cost Breakdown (FY13)
$0
$40
$80
$120
$160
2006 2008 2010 2012 2020
FC
Sys
tem
s C
os
t ($
/kW
net)
Projected Transportation Fuel Cell System Cost at 500,000 units/year
The Electrode Catalyst Challenges – Demand for Reducing
or Replacing Pt Usage
US DOE Technical Targets: Electrocatalysts for
Transportation Applications
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a PGM content and loading targets may have to be lower to achieve system cost targets.
b Rated power operating point depends on MEA temperature and is defined as the voltage at which V = 77.6 / (22.1 + T[°C]).
c Steinbach et al. (3M), “High-Performance, Durable, Low-Cost Membrane Electrode Assemblies for Transportation Applications,” 2014 Annual Merit Review,
http://www.hydrogen.energy.gov/pdfs/review14/fc104_steinbach_2014_o.pdf
d Based on MEA gross power at 150 kPa abs. Measured at 0.692 V and 90°C, satisfying Q/ΔT < 1.45 kW/°C. At 250 kPa abs status is 0.12 g/kW.
e Measured using protocol in Table P.1.
f Kongkanand et al. (General Motors), “High-Activity Dealloyed Catalysts,” 2014 Annual Merit Review, http://www.hydrogen.energy.gov/pdfs/review14/fc087_kongkanand_2014_o.pdf
g Measured using protocol in Table P.2.
h B. Popov et al., “Development of Ultra-low Doped-Pt Cathode Catalysts for PEM Fuel Cells,” 2015 Annual Merit Review,
http://www.hydrogen.energy.gov/pdfs/review15/fc088_popov_2015_o.pdf.
i D.J. Liu (ANL), “Novel Non-PGM Catalysts from Rationally Designed 3-D Precursors,” 2015 Annual Merit Review, http://www.hydrogen.energy.gov/pdfs/review15/fc118_liu_2015_p.pdf
j Target is equivalent to PGM catalyst mass activity target of 0.44 A/mgPGM at 0.1 mgPGM/cm2.
Recent DOE FCTO Initiatives in Energy Material Network
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ANL, LBL, LANL, NREL, ORNL
Fuel Cell Performance and Durability
ANL, LANL, NREL, ORNL
PGM-free electrocatalysts for next-
generation fuel cells
Examples of Recent Progresses in PGM-free and
Ultralow Pt Catalyst & Membrane Electrode
Developments at Argonne
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Next Generation PGM-free Catalyst – Addressing Catalyst &
Electrode Designs Simultaneously
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Improving activity through rationally designed precursors – MOFs/POPs
Improving mass/charge transports through nanofibrous network
Volumetric Activity Turn-Over-Freq. x Site Density
• Argonne’s nano-fibrous network provides higher surface area and nearly exclusive micropores
• New electrode offers enhanced mass transport and charge transfer via a unique micro-macro-porous nano-network
Conventional New ANL design Conventional ANL nano-network
New nano-network architecture not only increases surface area but also site density
New 3-D precursors breaks away from 50-years of square-planar molecular approach
•Argonne introduced Metal-organic-framework & porous organic polymer as next-generation catalyst precursors• “Support-free” and pore-former free •Uniform distribution & high active site
density
“One-Pot” Synthesis of MOF(ZIF)-based TM/N/C Catalysts –
Impact of Ligands
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(a)
(c)
(b)
(d)Solid State Reaction
ZnO
Fe complexIm mIm
eIm abIm
Different MOFsOrganic Ligands
+
TM/N/C Catalysts
D. Zhao, J.-L. Shui, L. R. Grabstanowicz, C. Chen, S.M. Commet, T. Xu, J. Lu, and D.-J. Liu, Advanced Materials, 2014, 26, 1093–1097 (Frontpiece article)J. Shui, C. Chen, L. R. Grabstanowicz, D. Zhao and D.-J. Liu, Proceedings of
National Academy of Sciences, U. S. A. 2015, vol. 112, no. 34, 10629
D.-J. Liu, J. Shui, C. Chen, US Patent 9,350,026
Simple solid-state synthesis, solvent-free and no separation needed
Very low-cost materials for ZIF synthesis
Versatile process of screening various N-containing ligands
Th
erm
al
Ac
tiva
tion
Fe-doped ZIF Catalyst Activities in Acidic Media were
Evaluated by RRDE and in PEM Fuel Cell
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0.0 0.2 0.4 0.6 0.8 1.0-6
-5
-4
-3
-2
-1
0
E / V vs. RHE
Cu
rre
nt
De
ns
ity
/ m
A c
m-2 Zn(Im)
2TPIP
Zn(mIm)2TPIP
Zn(eIm)2TPIP
Zn(4abIm)2TPIP
0.0 0.2 0.4 0.6 0.83.5
3.6
3.7
3.8
3.9
4.0
Zn(Im)2TPIP
Zn(mIm)2TPIP
Zn(eIm)2TPIP
Zn(4abIm)2TPIPE
lec
tro
ns
Tra
ns
ferr
ed
E / V vs. RHE
0 500 1000 1500 2000 2500 30000.0
0.2
0.4
0.6
0.8
1.0
Po
wer
Den
sity
/ m
W c
m-2
Current Density / mA cm-2
Cel
l Vo
ltag
e / V
Zn(mIm)2TPIP
Zn(eIm)2TPIP
Zn(4abIm)2TPIP
Zn(Im)2TPIP
0
100
200
300
400
500
600
700
10 100 10000.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
Volumetric current density (A cm-3)
iR-f
ree v
olt
ag
e / V
Zn(mIm)2TPIP
Zn(eIm)2TPIP
Zn(4abIm)2TPIP
Zn(Im)2TPIP
RRDE experiments demonstrated the activity
influenced by ZIF ligands
Such influence is also reflected in MEA /fuel
cell performance testings
T = 80 °CPH2 = PO2 = 1.5 Bar
100% RHO2 saturated 0.1 M HClO4
1600 RPM
Rational Design Combined with Process Optimization Led
to Excellent Fuel Cell Performances in both O2 & Air
0 200 400 600 800 1000 1200 1400 16000.0
0.2
0.4
0.6
0.8
1.0
Current Density (mA/cm2)
Cell P
ote
nti
al (V
)0
100
200
300
400
500
Po
wer
Den
sit
y (
mW
/cm
2)
0 500 1000 1500 2000 2500 3000 3500 4000
0.2
0.4
0.6
0.8
1.0
Current Density (mA cm-2)
Ce
ll P
ote
nti
al (V
)
0
200
400
600
800
1000
Po
wer
Den
sit
y (
mW
cm
-2)
Condition: Pair or PO2= PH2 = 1 bar (back pressure = 7.3 psig) fully humidified; T = 80 °C; N-
211 membrane; 5 cm2 MEA; cathode catalyst = 3.5 mg/cm2, anode catalyst = 0.4 mgPt/cm2.
P = 924 mW/cm2 @ 0.38V
P = 855
mW/cm2 @
0.47V
One-bar Oxygen
P = 437 mW/cm2 @ 0.45V
P = 358
mW/cm2 @
0.54V
One-bar Air
Engineering catalyst morphology and MEA architecture can alter fuel
cell performances between kinetic and mass-transport limited regions
MEA 1 MEA 2MEA 1 MEA 2
Fe-doped ZIF Catalysts Showed Excellent Activities &
Durability in Alkaline Medium
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0.2 0.4 0.6 0.8 1.0 1.2
-5
-4
-3
-2
-1
0
Cu
rre
nt
De
ns
ity
(m
A c
m-2
)
Pt/C, 60 gptcm-2
Zn(eIm)2TPIP
Zn(mIm)2TPIP
Zn(4abIm)2TPIP
Zn(Im)2TPIP
E(V vs. RHE)
10-3
10-2
10-1
100
101
102
0.8
0.9
1.0
1.1
1.2 Pt/C, 60 ugptcm
-2
Zn(eIm)2TPIP
Zn(mIm)2TPIP
Zn(4abIm)2TPIP
Zn(Im)2TPIP
E(V
) v
s R
HE
Kinetic current density (mA cm-2)
0.2 0.4 0.6 0.83.4
3.6
3.8
4.0
Pt/C, 60 ugptcm-2
Zn(eIm)2TPIP
Zn(mIm)2TPIP
Zn(4abIm)2TPIP
Zn(Im)2TPIPEle
ctr
on
s T
ran
sfe
red
E (V vs. RHE)
0 2000 4000 6000 8000 100000
20
40
60
80
100
De
via
tio
n f
rom
in
itia
l i K
(%
)
Cycle Number
Pt/C
Zn(eIm)2TPIP
Zn(mIm)2TPIP
RRDE showed 40 mV improvement over Pt/C at E1/2
Higher Tafel slop than Pt/C observed
O2 saturated 0.1 M KOH
1600 RPM
Electron transfer was less efficient than Pt/C
Durability under voltage cycling surpassed Pt/C
Cycling potential
0 to 1.2 V RHE
0.0 0.2 0.4 0.6 0.8 1.00
1
2
3
4
Co(Im)2
Co(mIm)2
Co(mIm)2/ZIF8
Ele
ctr
ons T
ransfe
rred
n
E (V) vs. RHE
15
Co-ZIFs as Precursors for Fe-free, PGM-free Catalysts
Mitigation of MEA degradation by Fe induced Fenton reaction requires alternative transition metals
In Co-ZIF, Co is also coordinated by N from four imidazole with unit volume packing density as high as 3.6 × 1021/cm3!
High BET surface area ~ 1500 m2/g was achieved in our lab recently 0.0 0.2 0.4 0.6 0.8 1.0
-5
-4
-3
-2
-1
0
Co(Im)2
Co(mIm)2
Co(mIm)2/ZIF8
Curr
ent D
ensity (
mA
/cm
2)
E (V) vs. RHE
E1/2 = 0.75 V
n approach to 4
Co(Im)2 Co(mIm)2 Co/Zn(mIm)2
Co/N4 Coordination Chemistry
Formation of bimetallic MOFs through metal exchange enables the
flexibility of controlling non-volatile TM content
Promising Activity of Co-ZIF Derived Catalyst was achieved
at MEA/Fuel Cell Level
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Condition: PO2 = PH2 = 1 bar (back pressure = 7.3 psig) fully humidified; T = 80 °C; N-211 membrane;
5 cm2 MEA; cathode catalyst = 4 mg/cm2, anode catalyst = 0.3 mgPt/cm2.
1 10 100 10000.6
0.7
0.8
0.9
1.0
Ce
ll P
ote
nti
al
(V)
Cell Current Density (mA/cm2)
OCV = 0.92 V
0 200 400 600 800 1000 1200 1400 16000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Ce
ll P
ote
nti
al
(V)
Current Density (mA/cm2)
IA @ 0.8 V = 28 mA/cm2
iR-free
The Co-only catalyst showed the best-of-the-class performance in a signal fuel cell study
Initial MEA/single fuel cell tests of the catalyst from heat-treated
binary Co(mIm)2/Zn(mIm)2 showed a promising performance
L. Chong, et. al. ChemElectroChem. 2016, 3, 1 – 6, DOI: 10.1002/celc.201600163
Reducing PGM Usage through Synergistic PGM-free/
Ultralow-Pt Catalyst Approach
17
Condition: PO2 = PH2 = 1 bar (back pressure = 7.3 psig) fully humidified; T = 80 °C; N-211 membrane; 5 cm2 MEA; cathode catalyst = 0.9 mg/cm2, anode catalyst = 0.35 mgPt/cm2.
0 1 2 3 4 50.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Current Density / A cm-2
iR-f
ree
Vo
lta
ge
/ V
PGM-free
ANL-2 Pt = 0.039 mg/cm2
ANL-1 Pt = 0.039 mg/cm2
Low-Pt/XC-72, Pt = 0.05 mg/cm2
Commericial, Pt = 0.35 mg/cm2
Fig. 5
Synergetic Catalysis Led to Improvement to Durability
0k
30k
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.50.0
0.2
0.4
0.6
0.8
1.0
iR
-fre
e c
ell
voltge (
V)
Current density / A cm-2
Condition: N-211 membrane; 5 cm2 MEA; cathode catalyst = 0.9 mg/cm2 or 0.039mgPt/cm2
anode catalyst = 0.4 mgPt/cm2, Cycling PN2= PH2 = 1 bar, 100% RH, T = 80 °C, voltage 0.6 V to 1.0 V, testing PO2= PH2 = 1 bar (back pressure = 7.3 psig) 100% RH.
Acknowledgement
Nancy Garland (DOE Fuel Cell Technologies Office) and John Kopasz, Tom Benjamin, for providing slides on recent fuel cell activities under DOE-FCTO
US DOE, Fuel Cell Technologies Office
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