The Solid-Phase Synthesis of an Fe-N-C Electrocatalyst for High-Power Proton-Exchange Membrane Fuel Cells

Article abstract of DOI:10.1002/anie.201709597

The environmentally friendly synthesis of highly active Fe-N-C electrocatalysts for proton-exchange membrane fuel cells (PEMFCs) is desirable but remains challenging. A simple and scalable method is presented to fabricate Fe^II-doped ZIF-8, which can be further pyrolyzed into Fe-N-C with 3 wt % of Fe exclusively in Fe-N₄ active moieties. Significantly, this Fe-N-C derived acidic PEMFC exhibits an unprecedented current density of 1.65 A cm^?2 at 0.6 V and the highest power density of 1.14 W cm^?2 compared with previously reported NPMCs. The excellent PEMFC performance can be attributed to the densely and atomically dispersed Fe-N₄ active moieties on the small and uniform catalyst nanoparticles.

Full text of DOI:10.1002/anie.201709597

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Angewandte
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Accepted Article
Title: Environmental-Friendly Solid Synthesis of Fe-N-C Electrocatalyst
with Fe Exclusively in Atomically Dispersed Fe-N4 Moieties for
High-Power Proton Exchange Membrane Fuel Cells
Authors: Qingtao Liu, Xiaofang Liu, Lirong Zheng, and Jianglan Shui
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201709597
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10.1002/anie.201709597
Angewandte Chemie International Edition
COMMUNICATION
Environmental-Friendly Solid Synthesis of Fe-N-C Electrocatalyst
with Fe Exclusively in Atomically Dispersed Fe-N4 Moieties for
High-Power Proton Exchange Membrane Fuel Cells
Qingtao Liu,[a] Xiaofang Liu,*[a] Lirong Zheng,[b] and Jianglan Shui*[a]
Abstract: Environmental-friendly synthesis of highly active Fe-N-C
electrocatalyst for proton exchange membrane fuel cells (PEMFCs)
is desirable but remains challenging. Herein, we report a green,
simple and scalable method to fabricate Fe(II)-doped ZIF-8, which
can be further pyrolyzed into Fe-N-C with 3 wt.% of Fe exclusively in
Fe-N4 active moieties. Significantly, this Fe-N-C derived acidic
PEMFC exhibits an unprecedented current density of 1.65 A cm-2 at
0.6 V and the highest power density of 1.14 W cm-2 compared with
previously reported NPMCs. The excellent PEMFC performance can
be attributed to the densely and atomically dispersed Fe-N4 active
moieties on the small and uniform catalyst nanoparticles.
been clearly identified, and the fuel cell performance still needs
to be improved to promote their practical application.
The Fe-N-C parameters depend on the synthesis process,
which typically involves a mixing of carbon, nitrogen and iron
precursors, plus an annealing to obtain Fe-Nx active moiety
doped porous carbon.[8] Impurities of Fe/Fe3C nanoparticles
(NPs) are usually formed due to the agglomeration of Fe atoms,
leading to a low utilization of Fe precursors and a low dispersion
density of Fe-Nx moieties.[9] Although an intense acid wash can
remove Fe/Fe3C NPs, it readily corrodes the active sites as well
and changes the composition of as-annealed Fe-N-C.[4b, 8c, 10] To
enhance the catalytic activity, an ammonia post-treatment is
commonly applied to introduce more N-dopants into Fe-N-C.[4a,
Proton exchange membrane fuel cells (PEMFCs) are ideal
clean energy systems that efficiently convert chemical energy of
hydrogen/oxygen to electricity through electrochemical
reactions.[1] The application of PEMFCs is, however, hindered by
the scarcity and intolerable cost of precious metal Pt which is the
most efficient catalyst so far for oxygen reduction reaction
(ORR), and accounts for ~40% of the fuel cell cost.[2] As a non-
precious metal catalyst (NPMC), Fe-N-C decorated with Fe-N4
active moieties has emerged as a promising alternative to Pt for
its high initial performance close to commercial Pt/C(20%) in
acidic PEMFCs.[3] The maximum power densities (Pmax) of these
Fe-N-C derived PEMFCs have reached above 0.9 W cm-2 or
even over 1 W cm-2 to date (the largest Pmax of 1.06 W cm-2
achieved at 2 bar H2/O2@80 °C in 2017).[4]
Although the three-electrode system (half-cell) is efficient
for a fast judgement of the NPMC catalytic activity, PEMFC
measurement is more valuable for comprehensively evaluating
catalyst properties in the actual working condition.[5] The NPMC
fuel cell performance is commonly determined by two factors.
One is the mass transport property of the catalyst layer, which
influences the utilization of the active sites and the polarization
of the fuel cell;[6] the other is the catalyst parameters, including
the composition and the dispersion density of active sites, and
the catalyst morphology and size which in turn affect the first
factor.[4b, 7] Due to the lower activity, Fe-N-C catalyst layers (CLs)
are usually much thicker than Pt/C layers in PEMFCs, which
results in higher internal resistances and consequently more
serious polarization, faster current drop and smaller Pmax. So far,
the effects of Fe-N-C morphology, size and active-site
distribution on the PEMFC current and power densities have not
8b, 11]
Besides, considerable amounts of solvents (e.g. alcohol
and organic solvents)[4a,
and assistant reagents (e.g.
b, 5a, 8b]
surfactants)[12] are often used for precursor preparation, thus
producing numerous waste. No matter solvents/assistant
reagents or ammonia/acids, they increase environmental burden
and fabrication cost, which would be serious problems for the
mass production of Fe-N-C. Therefore, it is necessary to
develop a green, low-cost, facile and scalable method to
fabricate high quality Fe-N-C catalyst with favorable morphology
and less Fe impurities, to meet the application needs in future.
Herein, Fe(II)-doped zeolitic imidazolate frameworks (ZIF-
8) were successfully prepared, for the first time, by a one-step
solid synthesis with no assistant reagents/solvents or waste.
After a pyrolysis under Ar atmosphere, iron(II) ions were
exclusively converted into atomically dispersed Fe-N4 moieties in
the final catalyst (3 wt.% Fe) with no needs of post-acid or -
ammonia treatments. In a 5 cm2 PEMFC, our Fe-N-C catalyst
achieved unprecedentedly high power densities of 1.14 and 1.11
W cm-2 with 2.5 and 2.0 bar H2/O2, respectively. The highest
current densities of 0.31 and 1.65 A cm-2 were also recorded at
0.8 and 0.6 V, respectively.
[a]
[b]
Q. Liu, Assoc. Prof. X. Liu, Prof. J. Shui
School of Materials Science and Engineering
Beihang University
No. 37 Xueyuan Road, Beijing 100083, China
E-mail: liux05@buaa.edu.cn; shuijianglan@buaa.edu.cn
Dr. L. Zheng
Beijing Synchrotron Radiation Facility, Institute of High Energy
Physics, Chinese Academy of Sciences
No. 19 Yuquan Road, Beijing 100049, China
Figure 1. a) Scheme of the solid synthesis of Fe-doped-ZIF-8 crystal and
carbonization for final Fe-N-C catalyst, b) XRD patterns of ZIF-8, Fe2-Z8 and
Fe2-Z8-C, c) SEM image of Fe2-Z8 (Inset: photo image).
Supporting information for this article is given via a link at the end
of the document.
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10.1002/anie.201709597
Angewandte Chemie International Edition
COMMUNICATION
The solid synthesis of Fe-N-C catalyst is illustrated in
Figure 1a. Firstly, a powder mixture of 2-methylimidazole (2MIm),
ZnO and ferrous oxalate (FeC2O4·2H2O, FeOx) was sealed in an
autoclave under argon, and heated at 220 °C to form Fe(II)-
doped ZIF-8 crystals by a one-step solvent-free process. 2MIm
was melted at 220 °C ensuring a well contact with ZnO and a
homogeneous crystallization. FeOx decomposed simultaneously
releasing Fe2+ to partially replace Zn2+, producing the
coordinated Fe-N4 in the doped ZIF-8 crystal. The molar
percentage of Fe (in all metal ions) was 2 at.%, and the
corresponding doped ZIF-8 was denoted as Fe2-Z8. Importantly,
no waste or by-product was produced during the solid synthesis
of Fe2-Z8. The identical XRD diffraction pattern of Fe2-Z8 to that
of ZIF-8 indicates the successful incorporation of Fe2+ into ZIF-8
framework (Figure 1b). Meanwhile, the Fe2+ doping enhanced
the crystallinity of Fe2-Z8 and darkened its color compared with
the white ZIF-8 powder as observed by scanning electronic
microscopy (SEM) and photo image in Figure 1c (ZIF-8
morphology was supplied below). The synthesis of Fe2-Z8 could
be easily scaled up because no liquid was used and therefore
the required reaction space was small (e.g. a 50 ml autoclave for
tens of grams of products in one batch) (Figure S1). It implies
that our method is particularly suitable for mass production.
Subsequently, the large Fe2-Z8 crystals were ball-milled into
powder, and washed quickly in a dilute polyvinyl pyrrolidone
(PVP) solution to coat a molecular layer of PVP on Fe2-Z8
which prevented the individual particles from merging together
during the annealing. It is noteworthy that the PVP solution did
not produce detectable waste because the dilute PVP solution
could be circularly utilized by adding new PVP powder. The
PVP-coated Fe2-Z8 was then carbonized at 1000 °C in Ar to
obtain the final Fe2-Z8-C electrocatalyst without any further
treatment. Owing to the existence of immediately available
nitrogen atoms and the firm bonding of Fe-N coordination to the
neighboring carbon atoms of the whole framework, Fe atoms
were isolated and converted into densely dispersed Fe-N4 active
moieties without aggregation into Fe NPs, as proved by the XRD
(Figure 1b) and the following images and spectra results. As no
assistant reagent was used in preparing Fe2-Z8, and neither
ammonia nor acid treatment was applied, our synthesis is an
environmental-friendly, low-cost, scalable and facile fabrication
process.
The morphology and microstructure of Fe2-Z8-C were
characterized by SEM, transmission electron microscopy (TEM),
scanning transmission electron microscopy (STEM) and Raman
spectrum. Figures 2a and S2 show the amorphous structure of
Fe2-Z8-C particles with sub-micron sizes. The mapping images
in Figure 2b indicate that C, N and Fe elements uniformly
distribute over the entire particles. Furthermore, Fe atoms were
observed by the high angle annular dark-field STEM (HAADF-
STEM) at atomic resolution. As shown in Figures 2c and S3, the
high density of Fe single-atoms (highlighted by red circles) on
the carbon substrate implies the densely and atomically
dispersed Fe-Nx moieties, whose structure will be identified latter.
As expected for the carbonized ZIF-8 material, the obtained
Fe2-Z8-C possesses a highly microporous structure with high
Brunauer-Emmett-Teller (BET) surface area of 1265 m2 g-1
(Figure S4), which are favorable for hosting numerous Fe-Nx
active moieties that are essential for the high activity and power
density of Fe2-Z8-C in PEMFCs. The local and electronic struc-
Figure 2. Images and spectra characterizations of Fe2-Z8-C. (a) HRTEM
image, (b) STEM images and corresponding elemental mapping, (c) HAADF-
STEM images, (d) normalized XANES at Fe K-edge, (e) Fourier-transformed
EXAFS of Fe2-Z8-C with references.
ture of iron atoms in Fe2-Z8-C were further investigated by X-ray
absorption near-edge structure (XANES) and extended X-ray
absorption fine structure (EXAFS). The XANES spectra of Fe K-
edge in Figure 2d show the similarity of pre-edge characteristic
between Fe2-Z8-C and iron phthalocyanine (FePc) spectra
which display a fingerprint peak at 7115 eV corresponding to the
Fe-N4 porphyrin plane. Meanwhile the large difference between
Fe2-Z8-C and Fe foil spectra further confirms the absence of Fe
NPs in Fe2-Z8-C catalyst. As shown in Figure 2e, the Fourier
transformed EXAFS spectrum (without phase correction) of Fe2-
Z8-C exhibits a sole peak at ~1.6 Å assigning to the Fe-N
scattering paths, whereas the Fe-Fe and Fe-C peaks were not
11b]
detected.[3b,
Although EXAFS spectrum cannot clearly
distinguish Fe-N and Fe-O bonds,[13] the existence of iron oxides
was less possible since Fe2-Z8 did not contain oxygen element
and the annealing was conducted under the inert atmosphere.
The EXAFS data were further fitted in r-space and k-space as
shown in Figure S5, and the fitting parameters were summarized
in Table S1. It indicates that the isolated Fe atom was four-fold
coordinated by N atoms. Meanwhile one O2 molecule might be
adsorbed on the Fe atom in perpendicular to Fe-N4 plane as
shown in the inset of Figure 2d. So, all above structural
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10.1002/anie.201709597
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characterizations prove that the incorporated Fe(II) dopants
were completely converted into atomically dispersed Fe-N4
moieties in Fe2-Z8-C with no Fe/Fe3C NPs.
model at a constant potential of 0.5 V. Figure 3c shows a 98.2%
current retention for the Fe2-Z8-C after 10
k seconds,
significantly higher than 82.6% of Pt/C and 94.3% of Z8-Fe2-C.
The LSV curve of Fe2-Z8-C after the chronoamperometric test
shows a 17 mV decrease of E1/2, less than the 38 mV of Z8-Fe2-
C (Figure S8). Additionally, the electrochemical activities of the
as-prepared catalysts were evaluated in 0.1 M KOH electrolyte.
As presented in Figure 3d, Fe2-Z8-C processes an Eonset of
0.985 V and an E1/2 of 0.871 V, considerably higher than those
of Pt/C (0.974 V and 0.847 V respectively).
The strong adsorption of SCN- to Fe ions could impede the
absorption of O2 onto Fe-N4 sites and thus block the ORR on
these sites. Based on this phenomenon, a poisoning experiment
was performed by adding 0.01 M KSCN into the electrolyte
during the ORR test. A dramatic negative shift of half-wave
potential (56 mV) on LSV curves was observed (Figure S9),
which proved the high ORR activity of Fe2-Z8-C could be
ascribed to the Fe-N4 moieties. As discussed above, doping
Fe(II) into ZIF-8 ensured atomically dispersed and fixed Fe ions
in the precursor, which could be completely converted into Fe-N4
moieties during the pyrolysis when the Fe ion concentration was
below a threshold as will be discussed latter. It is believed that
the higher content of Fe-N4 active moieties on Fe2-Z8-C endows
its superior ORR properties to the Fe NPs-existed Z8-Fe2-C.
To further demonstrate the compositional and structural
advantages of densely distributed Fe-N4 active moieties in the
actual fuel cell working condition, Fe2-Z8-C was assembled in a
5 cm2 PEMFC as the cathode catalyst. Under absolute H2/O2
pressures of 2.5 bar and a catalyst loading of 2.8 mg cm-2, high
PEMFC activities and power densities were achieved with the
Figure 3. a) LSV curves, b) H2O2 yield and electron transfer number and c)
normalized i-t cures at 0.5 V (vs. RHE) of Fe2-Z8-C, Z8-Fe2-C, Pt/C(40%) in
0.5 M H2SO4 by RRDE tests. (d) LSV curves tested in 0.1 M KOH electrolytes.
Tests were performed in O2-saturated electrolytes at 1600 rpm with scan rate
of 10 mV s-1. The ring potential was set at 1.25 V vs. RHE.
For comparison, a control sample of Z8-Fe2-C was
prepared by physically mixing ZIF-8 with FeOx as the precursor
(see Supporting Information for the preparation
and characterizations). As shown in Figure S6,
Fe NPs formed during pyrolysis, and further
catalyzed the growth of CNTs and the
graphitization of carbon. According to XPS results,
not only the total N content but also the pyridinic
N/Fe-N4 ratio on Fe2-Z8-C surface was higher
than those on Z8-Fe2-C surface (Figure S7). It
thus further demonstrates that the Fe-N
coordination structure in Fe2-Z8 successfully
isolated Fe from agglomeration and produced
more Fe-N4 moieties compared with the mixture
of FeOx/ZIF-8.
The ORR activities of the catalysts were
firstly evaluated by the rotating ring-disk electrode
(RRDE) technique. The linear sweep voltammetry
(LSV) curve in Figure 3a shows the excellent
activity of Fe2-Z8-C with a high onset potential
(Eonset) of 0.902 V (defined as the potential with a
current density of 0.1 mA cm-2) and a half-wave
potential (E1/2) of 0.805 V in 0.5 M H2SO4, which
is comparable to the commercial Pt/C (E1/2: 0.822
V) and among the top level NPMCs. The low
H2O2 yield (below 1%) and the close-to-four
electron transfer number demonstrate a high
selectivity of 4 e- oxygen reduction reaction for
Fe2-Z8-C (Figure 3b). Furthermore, the durability
of Fe2-Z8-C was evaluated in an O2-saturated
acid electrolyte by the chronoamperometric test
Figure 4. I-V polarization and power density curves of a) Fe2-Z8-C, Z8-Fe2-C, and Pt/C(20%)
with cathode loadings of 2.8, 2.7 and 0.33 (Pt) mg cm-2 respectively; and b) Fe2-Z8-C with
indicated loadings; c) Tafel plot of Fe2-Z8-C (1.9 mg cm-2) measured under DOE(U.S.) stand: 1
bar; d) comparison between Fe2-Z8-C (2.8 mg cm-2) with or without applying PVP coating before
the carbonization of Fe2-Z8. PEMFC tests were applied in a 5 cm2 single cell with 80 °C H2/O2 at
flow of 0.3 L min-1 for H2 and 0.4 L min-1 for O2, 100%RH, 2.5 bar absolute pressure (except
specifically indicated). Membrane: NRE 211.
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10.1002/anie.201709597
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COMMUNICATION
current densities of 35, 310, and 1650 mA cm-2 at the potential
of 0.9, 0.8, and 0.6 V, respectively (Figure 4a), which are the top
performances among NPMC-derived PEMFCs, see Table S2.
Besides, we noticed that the polarization curves of Fe2-Z8-C
overlapped that of Pt/C(20%) from the open circuit voltage
(OCV) till 0.6 V, indicating a high PEMFC activity of Fe2-Z8-C
due to its high active-moiety density. More significantly, the Pmax
reached 1141 mW cm-2, and it only slightly decreased to 1110
mW cm-2 when the fuel pressure was reduced to 2 bar. These
extremely high power densities outperformed all reported
NPMCs measured under similar condition to the best of our
knowledge. In contrast, Z8-Fe2-C displayed relatively poor
PEMFC performances on both power density (Pmax = 880 mW
cm-2) and current density (150 mA cm-2@0.8 V) due to the waste
of Fe precursor and the reduction of active sites as
demonstrated above.
Interestingly, Figure 4b shows that the high Pmax could be
obtained within a wide range of Fe2-Z8-C loading, e.g. 1000 and
810 mW cm-2 for 1.9 and 0.91 mg cm-2, respectively. Even with a
very low loading of 0.63 mg cm-2, the PEMFC still achieved a
remarkably high Pmax of 740 mW cm-2. This phenomenon should
be attributed to the densely dispersed Fe-N4 moieties on Fe2-
Z8-C, which supplied sufficient activity at a thin catalyst layer.
Different from most previously reported NPMCs, whose Pmax
were usually obtained at a high loading near 4 mg cm-2,[4c, d, 14]
the Fe2-Z8-C achieved the best power performance with 2~3 mg
cm-2 catalysts. A high Fe2-Z8-C loading of 4.2 mg cm-2
generated a relatively low power density due to the large
thickness-induced high internal resistance (Figure S10), which
caused a fast voltage decay with the increased current. In
addition to the power density, the volumetric current density at
0.8 ViR-Free is another crucial parameter for judging the catalytic
activity of NPMCs. Because of the densely dispersed Fe-N4
active moieties over the high surface area microporous carbon
support, the Fe2-Z8-C delivered a high volumetric current
density of 81 A cm-3@0.8ViR-Free under U.S. DOE standard at the
loading of 1.9 mg cm-2 (Figure 4c, Figure S11).
It is worth mentioning that the PVP coating plays an
important role for Fe2-Z8-C to achieve the high PEMFC
performance. When the Fe2-Z8 was dipped in a dilute PVP
solution, a molecular layer of PVP was adsorbed on Fe2-Z8
surface (see Figure S12). The PVP coating could prevent the
fusion of Fe2-Z8 crystals because PVP was decomposed from
400 to 480 °C , while Fe2-Z8 already started to decompose
around 510 °C (Figure S13). Therefore, PVP coating could
prohibit the formation of large catalyst particles thus ensuring the
large surface utilization. In Figure 4d, it is seen that the Fe2-Z8-
C particles without PVP coating had a rather wide size
distribution with several-micron large particles. (See Figure S14
for more image information) In contrast, PVP coating resulted in
smaller and more uniform Fe2-Z8-C NPs with a higher surface
area and more micropores (Figure S15). Correspondingly, the
Fe2-Z8-C with PVP coating-treatment showed higher power and
current densities than its counterpart in PEMFCs. Interestingly,
the RDE results given in Figure S16, show the same Eonset and
E1/2 for Fe2-Z8-C with or without PVP coating on the precursor
Fe2-Z8. The non-consistent results by RDE and PEMFC
techniques suggest the measured results by the three-electrode
system (half-cell) may be not sufficient to predict the
performance of NPMCs in a real PEMFC, and meanwhile
emphasize the crucial role of PEMFC characterization of
NPMCs for evaluating their practical application potential.
The optimal iron content in the doped ZIF-8 was explored
by a series of characterizations of XRD, SEM, TEM, and RRDE.
At a low doping level (x  2), the crystallinity of Fex-Z8 was
improved and the brown color became darker with increasing Fe
content (Figure S17a-c). Whereas excessive amounts of Fe
dopants would lighten the crystal color and change the crystal
phase as proved by the appearance of new diffraction peaks for
Fe5-Z8. Although the new diffraction peaks did not appear in
Fe3.5-Z8 (Figure S17j), Fe NPs were found in Fe3.5-Z8-C as
shown in Figure S18c, d, suggesting Fe atoms began to
agglomerate at this density. Thus, 2 mole percent of Fe was
chosen to be the optimal doping level in our experiment, which
led to 3 wt.% atomically dispersed Fe atoms in Fe2-Z8-C as
determined by the XPS measurement (Figure S19). In Figure
S20, electrochemical tests proved that the catalyst with
atomically dispersed Fe atoms was an ideal structure to achieve
the highest catalytic activity. Despite the comparable activity of
Fe3.5-Z8-C to Fe2-Z8-C in the acid, the relatively weak
durability of Fe3.5-Z8-C (see Figure S20c) implies again that the
formation of Fe nanoparticles could decrease the stability of the
catalyst in the three-electrode system. In addition, the extension
of annealing duration from 1 hour to 2 hours promoted the ORR
activity because of the increased micropores and BET surface
area (Figure S21).
In summary, this work developed a facile, low cost,
environmental-friendly and scalable solid-synthesis method for a
highly active Fe-N-C electrocatalyst with Fe exclusively in Fe-N4
moieties. The as-prepared Fe2-Z8-C delivered the highest
current density of 1.65 A cm-2 at 0.6 V, and an unprecedented
power density of 1.14 W cm-2 in acidic PEMFCs. Even with low
catalyst loadings of 1.9 and 0.9 mg cm-2, its power density still
achieved 1.00 and 0.81 W cm-2 respectively. The densely and
atomically dispersed Fe-N4 active moieties as well as the
uniform and small catalyst nanoparticles were essential for the
excellent PEMFC performance. This work makes a step forward
toward the better fabrication of highly pure and active NPMCs
for PEMFC applications.
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (Grant No.21673014), and the “111“ Project
(B17002) funded by the Ministry of Education of China.
Keywords: Electrocatalysis; PEM fuel cell; Fe-N-C; Oxygen
reduction; Solid-phase synthesis
[1]
[2]
a) M. K. Debe, Nature 2012, 486, 43–51; b) M. Shao, Q. Chang, J.-P.
Dodelet, R. Chenitz, Chem. Rev. 2016, 116, 3594–3657; c) F. Jaouen,
E. Proietti, M. Lefevre, R. Chenitz, J. P. Dodelet, G. Wu, H. T. Chung, C.
̀
M. Johnston, P. Zelenay, Energy Environ. Sci. 2011, 4, 114–130; d) V.
Armel, S. Hindocha, F. Salles, S. Bennett, D. Jones, F. Jaouen, J. Am.
Chem. Soc. 2017, 139, 453–464.
a) H. A. Gasteiger, N. M. Marković, Science 2009, 324, 48–49; b) C.
Tang, Q. Zhang, Adv. Mater. 2017, 29, 1604103; c) Y. Liu, X. Yue, K. Li,
J. Qiao, D. P. Wilkinson, J. Zhang, Coordin. Chem. Rev. 2016, 315,
153–177; d) D. He, H. Tang, Z. Kou, M. Pan, X. Sun, J. Zhang, S. Mu,
This article is protected by copyright. All rights reserved.

10.1002/anie.201709597
Angewandte Chemie International Edition
COMMUNICATION
Adv. Mater. 2017, 29, 1601741; e) Z. Song, N. Cheng, A. Lushington, X.
Sun, Catalysts 2016, 6, 116.
X. X. Xu, B. C. Hu, H. W. Liang, Y. Lin, L. F. Chen, S. H. Yu, Angew.
Chem. Int. Ed. 2015, 54, 8179–8183; e) S. H. Ahn, X. Yu, A. Manthiram,
Adv. Mater. 2017, 1606534.
[3]
[4]
a) W. Zhang, W. Lai, R. Cao, Chem. Rev. 2017, 117, 3717–3797; b) Q.
Jia, N. Ramaswamy, U. Tylus, K. Strickland, J. Li, A. Serov, K.
Artyushkova, P. Atanassov, J. Anibal, C. Gumeci, S. C. Barton, M.-T.
Sougrati, F. Jaouen, B. Halevi, S. Mukerjee, Nano Energy 2016, 29,
65–82; c) X. Zeng, J. Shui, X. Liu, Q. Liu, Y. Li, J. Shang, L. Zheng, R.
Yu, Adv. Energy Mater. 2017, 1701345.
[9]
a) M. Ferrandon, A. J. Kropf, D. J. Myers, K. Artyushkova, U. Kramm, P.
Bogdanoff, G. Wu, C. M. Johnston, P. Zelenay, J. Phys. Chem. C 2012,
116, 16001–16013; b) W. Liu, L. Zhang, W. Yan, X. Liu, X. Yang, S.
Miao, W. Wang, A. Wang, T. Zhang, Chem. Sci. 2016, 7, 5758–5764;
c) P. Yin, T. Yao, Y. Wu, L. Zheng, Y. Lin, W. Liu, H. Ju, J. Zhu, X.
Hong, Z. Deng, G. Zhou, S. Wei, Y. Li, Angew. Chem. Int. Ed. 2016, 55,
10800–10805.
a) E. Proietti, F. Jaouen, M. Lefèvre, N. Larouche, J. Tian, J. Herranz,
J.-P. Dodelet, Nat. Commun. 2011, 2, 416; b) J. Shui, C. Chen, L.
Grabstanowicz, D. Zhao, D.-J. Liu, Proc. Natl. Acad. Sci. 2015, 112,
10629–10634; c) Y.-C. Wang, Y.-J. Lai, L. Song, Z.-Y. Zhou, J.-G. Liu,
Q. Wang, X.-D. Yang, C. Chen, W. Shi, Y.-P. Zheng, M. Rauf, S.-G.
Sun, Angew. Chem. Int. Ed. 2015, 54, 9907–9910; d) X. Fu, P. Zamani,
J. Y. Choi, F. M. Hassan, G. Jiang, D. C. Higgins, Y. Zhang, M. A.
Hoque, Z. Chen, Adv. Mater. 2017, 29, 1604456.
[10] a) D. Zhao, J. L. Shui, L. R. Grabstanowicz, C. Chen, S. M. Commet, T.
Xu, J. Lu, D. J. Liu, Adv. Mater. 2014, 26, 1093–1097; b) J. Li, Y. Song,
G. Zhang, H. Liu, Y. Wang, S. Sun, X. Guo, Adv. Funct. Mater. 2017,
27, 1604356.
[11] a) H. Meng, N. Larouche, M. Lefevre, F. Jaouen, B. Stansfield, J.-P.
̀
Dodelet, Electrochim. Acta 2010, 55, 6450–6461; b) A. Zitolo, V.
Goellner, V. Armel, M.-T. Sougrati, T. Mineva, L. Stievano, E. Fonda, F.
Jaouen, Nat. Mater. 2015, 14, 937–942; c) H. Shen, E. Gracia-Espino,
J. Ma, H. Tang, X. Mamat, T. Wagberg, G. Hu, S. Guo, Nano Energy
2017, 35, 9–16.
[5]
a) C. Zhang, Y. C. Wang, B. An, R. Huang, C. Wang, Z. Zhou, W. Lin,
Adv. Mater. 2017, 29, 1604556; b) W. J. Jiang, L. Gu, L. Li, Y. Zhang, X.
Zhang, L. J. Zhang, J. Q. Wang, J. S. Hu, Z. Wei, L. J. Wan, J. Am.
Chem. Soc. 2016, 138, 3570–3578.
[6]
[7]
[8]
C. Zhu, H. Li, S. Fu, D. Du, Y. Lin, Chem. Soc. Rev. 2016, 45, 517–531.
M. Zhou, H.-L. Wang, S. Guo, Chem. Soc. Rev. 2016, 45, 1273–1307.
[12] X. J. Wang, H. G. Zhang, H. H. Lin, S. Gupta, C. Wang, Z. X. Tao, H.
Fu, T. Wang, J. Zheng, G. Wu, X. G. Li, Nano Energy 2016, 25, 110–
119.
a) F. Jaouen, J. Herranz, M. Lefevre, J.-P. Dodelet, U. I. Kramm, I.
̀
Herrmann, P. Bogdanoff, J. Maruyama, T. Nagaoka, A. Garsuch, J. R.
[13] Y. Chen, S. Ji, Y. Wang, J. Dong, W. Chen, Z. Li, R. Shen, L. Zheng, Z.
Zhuang, D. Wang, Y. Li, Angew. Chem. Int. Ed. 2017, 56, 6937–6941.
[14] Y. Yao, Y. You, G. Zhang, J. Liu, H. Sun, Z. Zou, S. Sun, ACS Appl.
Mater. Interfaces 2016, 8, 6464–6471.
Dahn, T. Olson, S. Pylypenko, P. Atanassov, E. A. Ustinov, ACS Appl.
Mater. Interfaces 2009, 1, 1623–1639; b) M. Lefevre, E. Proietti, F.
̀
Jaouen, J.-P. Dodelet, Science 2009, 324, 71–74; c) G. Wu, K. L. More,
C. M. Johnston, P. Zelenay, Science 2011, 332, 443–447; d) Z. Y. Wu,
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10.1002/anie.201709597
Angewandte Chemie International Edition
COMMUNICATION
Table of Contents
COMMUNICATION
An environmental-friendly, facile,
low cost, and scalable solid-
synthesis method was developed
Qingtao Liu, Xiaofang Liu,* Lirong
Zheng, and Jianglan Shui*
Page No. – Page No.
for
a
highly active Fe-N-C
electrocatalyst with Fe exclusively
in Fe-N4 moieties. The as-prepared
Environmental-Friendly Solid
Synthesis of Fe-N-C
Electrocatalyst with Fe
Fe2-Z8-C
delivered
an
unprecedented power density of
1.14 W cm-2 in the acidic PEMFC,
which was attributed to the densely
and atomically dispersed Fe-N4
active moieties, and the small
catalyst nanoparticles.
Exclusively in Atomically
Dispersed Fe-N4 Moieties for
High-Power Proton Exchange
Membrane Fuel Cells
This article is protected by copyright. All rights reserved.