FeP and FeP2 nanowires for efficient electrocatalytic hydrogen evolution reaction

Article abstract of DOI:10.1039/c5cc09832g

We report achieving of efficient electrocatalytic hydrogen evolution reaction using composition-controlled iron phosphide (FeP and FeP₂) nanowires. The respective Tafel slopes of nanowire arrays were 39 and 37 mV dec^-1 in 0.5 M H₂SO₄, and 75 and 67 mV dec^-1 in 1 M KOH. The richer P composition produced excellent electrocatalytic efficiency.

Full text of DOI:10.1039/c5cc09832g

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: C. Y. Son, I. H.
Kwak, Y. R. Lim and J. Park, Chem. Commun., 2016, DOI: 10.1039/C5CC09832G.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/chemcomm

Please do not adjust margins
ChemComm
Page 1 of 5
View Article Online
DOI: 10.1039/C5CC09832G
Journal Name
ARTICLE
FeP and FeP2 Nanowires for Efficient Electrocatalytic Hydrogen
Evolution Reaction†
Received 00th January 20xx,
Accepted 00th January 20xx
Chang Yong Son, In Hye Kwak, Young Rok Lim and Jeunghee Park*
DOI: 10.1039/x0xx00000x
www.rsc.org/
We report achieving efficient electrocatalytic hydrogen evolution demonstrated the relatively high electrocatalytic activity of P-rich
reaction using composition-controlled iron phosphide (FeP and FeP2 NWs for HER in both acidic and basic media.
FeP2) nanowires. The respective Tafel slopes of nanowire arrays
were 39 and 37 mV dec-1 in 0.5 M H2SO4, and 75 and 67 mV dec-1 phosphidation reaction of pre-grown vertically aligned Fe2O3 NWs
in KOH. The richer P composition produced excellent with phosphine (PH3) gas. This method has many advantages,
electrocatalytic efficiency.
FeP and FeP2 NW arrays were synthesized through the
1
M
including high yield, short reaction time, and excellent
reproducibility and requires no additional fabrication processes.
Hydrogen generated from water splitting has great potential for use The detailed experimental procedure is described in the Electronic
as a clean, recyclable, and relatively low-cost energy source. Over Supplementary Information (ESI†)
the past decade, fundamental progress has been made in
developing novel catalyst materials for water-splitting reactions.
However, constructing an efficient device capable of producing
hydrogen at a scale and cost that can compete with fossil fuels
remains a significant challenge. Currently, platinum (Pt) is state-of-
art catalyst as only small overpotentials are required for high
reaction rates. However, the scarcity and high cost of Pt may limit
its widespread technological use. This limitation has motivated
significant efforts toward replacing Pt with earth-abundant non-
noble metal or metal-free materials.1-8 Transition metal phosphides
are one type of attractive semiconductor materials, which have a
low band gap, making them electrically conductive, and exhibit
good stability in acidic and basic media compared to their pure
metal counterparts.9-39
.
Despite the remarkable hydrogen evolution reaction (HER) activity
of metal phosphides used in water splitting, controlling the
composition of these materials to increase their efficiency remains
challenging, and only a few cases have been reported. Recently,
Schaak’s group reported that CoP exhibits better HER catalytic
Fig. 1 SEM micrographs of (a) Fe2O3 and (b) FeP2 NW arrays grown
on substrates. Photographs show a red Fe2O3, a black FeP, and a
grey FeP2 NW arrays on a 1×1 cm2 size Fe foil. HRTEM and
corresponding FFT images of orthorhombic-phase (c) FeP and (d)
FeP2 NWs. EDX mapping and line-scan profiles of Fe K shell, P K
shell, and O K shell showing the Fe3O4-FeP and Fe3O4-FeP2 core-shell
structures
activity than Co2P.27 Additionally,
a number of works have
confirmed the higher HER efficiency of P-rich Ni5P4 nanostructures
and the lower efficiency of P-deficient Ni12P5 compared to Ni2P.29-31
Motivated by these results, herein, we developed novel synthetic
methods to produce FeP and FeP2 nanowires (NWs) with two
different morphologies; one is NW array directly grown on
substrates and the other one is freestanding NWs. We
Fig. 1a presents the SEM image of the vertically aligned Fe2O3 NWs.
The photograph shows the homogenous growth of Fe2O3 NWs (red)
over a large area of substrate (1×1 cm2). These NWs were
synthesized by oxidizing Fe foil, as described elsewhere.40 The
average length of these NWs is 10 ꢀm. After the phosphidation
reaction, red color (Fe2O3) becomes black (FeP) or grey (FeP2). The
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 2 of 5
View Article Online
DOI: 10.1039/C5CC09832G
ARTICLE
Journal Name
SEM images and photographs show the homogenous growth of FeP activation-controlled current density region. The Tafel slopes are
and FeP2 NWs over entire substrates (Fig. 1b). Control over the 39, 37, and 30 mV dec-1 (dec = decade) for FeP, FeP2, and Pt/C,
composition was achieved by varying the reaction temperature; respectively. The respective exchange currents are 0.17, 0.55, and
350 °C for FeP and 400 °C for FeP2. X-ray diffraction (XRD) pattern 3.23 mA cm-2. The results confirm the higher catalytic activity of
analysis confirmed the orthorhombic phase of the FeP (JCPDS No. FeP2 relative to FeP, which is consistent with the results obtained
78-1443, a = 5.193 Å, b = 3.099 Å, c = 5.792 Å) and FeP2 (JCPDS No. for CoP, CoP2, Ni12P5, Ni2P, and Ni5P4.27,29-31
Table 1 Experimental overpotential and Tafel plot parameters of
71-2234, a = 4.972 Å, b = 5.656 Å, c = 2.723 Å) NWs (see the ESI ,
†
FeP and FeP2 NWs
Fig. S1). Both samples contain the Fe3O4 phase, which was probably
produced by the reduction of Fe2O3 under hydrogen-rich condition
during the phosphidation reaction. We separately prepared the
Fe3O4 NW array by the thermal reaction of as-grown Fe2O3 at 650 °C
using hydrogen gas. The density of the as-grown FeP and FeP2 NWs
is measured to be ca. 60 and 45 mg cm-2, respectively.
η
(mV)a
96
b
J0
(mA cm-2)c
0.17
Electrolyte
Sample
(mV dec-1)b
FeP array
FeP2 array
FeP freed
FeP2 free
Pt/C
39
37
61
0.55
Acid:
0.5 M
H2SO4
193
128
15
66
0.039
0.17
Fig. 1c presents the high-resolution transmission electron
microscopy (HRTEM) and fast-Fourier transform (FFT) images of the
FeP NWs. The average diameter is 250 nm. A rough surface was
observed along the entire wire axis of the FeP NWs. The NW’s edge
has been magnified to reveal the polycrystalline structure. The
lattice-resolved image of the single-crystalline domain shows that
the d-spacing between the neighboring (111) planes (d111) is 2.4 Å
(at the zone axis of [123]), which is consistent with that of
orthorhombic-phase FeP. Energy-dispersive X-ray fluorescence
(EDX) mapping and the line-scan profile of Fe K shell, P K shell, and
O K shell show that the atomic ratio of Fe and P is 1:1 in the outer
region and that the oxygen is mainly distributed inside the NW,
suggesting a Fe3O4-FeP core-shell structure.
40
30
3.23
FeP array
FeP2 array
FeP free
FeP2 free
Pt/C
194
189
274
253
90
75
0.035
0.035
0.095
0.032
0.87
67
Base:
1 M KOH
134
100
53
Overpotential at J=10 mA cm-2,
Parameters of the Tafel
a
b,c
equation: η = b log(J/J0), where η is the overpotential (measured), b
is the Tafel slope (mV dec-1), J is the current density (measured),
and J0 is the exchange current density (mA cm-2); d Freestanding
NWs.
0.10
The HRTEM and FFT images of the FeP2 NWs are shown in Fig. 1d.
The average diameter is 300 nm. Magnifying the image reveals the
surface’s polycrystalline nature. The d-spacing between the
neighboring (200) planes (d200) is 2.5 Å at the zone axis of [010],
which is consistent with that of orthorhombic-phase FeP2. EDX
mapping and line-scan profiles reveal the Fe3O4 phase in the cores
of the FeP2 NWs. The Fe and P exist at an atomic ratio of 1:2 in the
shell part of Fe3O4-FeP2 core-shell structures.
(a) 0.5 M H2SO4
(b) 0.5 M H2SO4
0
-10
-20
-30
-40
-50
c
e
d
V
Fe2O3
Fe3O4
FeP
m
0.05
0.00
9
3
=
b
P
e
F
c
e
d
FeP2 Pt/C
V
m
7
3
=
b
c
e
d
P
e
F
V
m
0
3
=
b
C
/
t
P
-0.05
0.2
-0.2
-0.1
0.0
-0.5
0.0
0.5
1.0
(c) 1 M KOH
(d) 1 M KOH
To evaluate the electrocatalytic HER performance, we performed
linear sweep voltammetry (LSV) using the as-grown NW arrays as
the working electrode. A typical three-electrode setup was used
0
-10
-20
-30
-40
-50
1
-
Fe2O
3 Fe3O4
c
b
e
d
V
V
m
0.1
0.0
7
6
=
b
FeP2 FeP Pt/C
(see the ESI
results.
†
for experimental details). Table 1 summarizes the
P
c
e
e
F
d
m
3
5
=
b
C
/
t
P
Fig. 2a shows the LSV curves (with iR-corrected) for FeP and FeP2
NWs in H2-saturated 0.5 M H2SO4 solution (scan rate: 2 mV s-1). The
potentials reported here were referenced to the reversible
hydrogen electrode (RHE) through standard calibration. The
overpotential (η) is defined as the applied potential (E) vs. RHE. For
-0.4
-0.3
-0.2
-0.1
0.0
-0.5
0.0
0.5
1.0
log J (mA cm-2)
E (V) vs. RHE
Fig. 2 LSV curves of the HER in (a) 0.5 M H2SO4 and (c) 1 M KOH for
Fe2O3, Fe3O4, FeP, and FeP2 NW arrays and a commercial Pt/C
reference, we also performed measurements using a commercial catalyst. (b), (d) Tafel plots derived from the LSV curves. Dotted
Pt/C catalyst (20 wt % Pt on Vulcan carbon black), exhibiting high
HER catalytic performance (with a near-zero overpotential). The
Pt/C (1 mg cm-2) was deposited on a glassy carbon (GC) electrode,
and the performance was examined at a rotation speed of 1600
rpm. The LSV curves of Fe2O3 and Fe3O4 NW array were measured,
confirming no HER catalytic activity. The overpotentials needed to
deliver 10 mA cm-2 current density were found to be 96, 61, and 15
mV for FeP, FeP2, and Pt/C, respectively.
lines show iR-corrected data for FeP and FeP2.
The Tafel slope of 30 mV dec-1 for Pt/C indicates that the HER
follows the Volmer-Tafel mechanism; H3O+ + e- → Hads+ H2O and
Hads + Hads → H2 (b = 30 mV dec-1). For FeP and FeP2 NWs, the
Volmer-Heyrovsky mechanism; H3O+ + e- → Hads+ H2O and Hads
+
H3O+ + e- → H2 + H2O (b = 40 mV dec-1), is at work. The Tafel slope
determined here is near the lowest value reported previously: 32
mV dec-1 measured for FeP nanoparticles on carbon cloth in 0.5 M
The catalysis kinetics for the HER was examined using Tafel plots
based on the Tafel equation: η = b log(J/J0) (Fig. 2b). The Tafel slope
(b) and exchange current density (J0) were obtained from the linear
portion in the low-potential region, which corresponds to the
H2SO4 by Sun’s group.15 Table S1 (see the ESI
†) summarizes the
previous works investigating FeP and FeP2.
The electrocatalytic HER performance was also measured in 1 M
This journal is © The Royal Society of Chemistry 20xx
2 | J. Name., 2012, 00, 1-3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 3 of 5
View Article Online
DOI: 10.1039/C5CC09832G
Journal Name
KOH, as shown in Fig. 2c. The overpotentials needed to deliver
ARTICLE
J
=
1 summarizes the current densities (needed to deliver 10 mA cm-2)
10 mA cm-2 were found to be 194, 189, and 90 mV for FeP, FeP2, and Tafel parameters. The FeP and FeP2 NWs showed Tafel slopes
and Pt/C, respectively. Correcting the raw data for iR losses of 66 and 40 mV dec-1 in 0.5 M H2SO4 and 134 and 100 mV dec-1 in 1
revealed even more impressive performance of FeP2 compared M KOH, respectively (Fig. S4, ESI†). The current densities are lower
to that of FeP. The linear portions of the Tafel plots were fit to the than those of the NW arrays. The chronoamperometric response
Tafel equation, yielding Tafel slopes of 75, 67, and 53 mV dec-1 for data indicate that the HER catalytic activity of FeP2 is more stable
FeP, FeP2, and Pt/C, respectively (Fig. 2d). The slope values suggest than that of FeP over long-term testing (8 h) in both acidic and basic
that the HER follows the Volmer-Heyrovsky mechanism. The Tafel media (Fig. S5, ESI†). The current attenuation of FeP2 is less than 5
slopes are comparable to that reported for FeP nanotubes on %. Therefore, we concluded that the richer P composition resulted
carbon cloth:
b
= 59.5 mV dec-1.22
in persistently excellent electrocatalytic efficiency upon cycling.
Fe0
707.1
The chronoamperometric response measurements confirm these
materials’ higher stability in base than in acid (see the ESI†, Fig. S2).
The FeP2 NWs are more stable than the FeP NWs, and current
attenuations of 20 % and 12 % (at -0.2 V) within 8 h were observed
in 1 M KOH for the FeP and FeP2 NWs, respectively. X-ray
photoelectron spectroscopy (XPS) data revealed the negligible
degradation of FeP2 NW during HER in 1 M KOH (Fig. S3, ESI†). The
SEM images and XRD pattern confirmed that the morphology and
phase of FeP2 NWs are nearly unchanged. It suggests that the FeP2
NWs are more competitive with the state-of-the-art HER catalysts
than the FeP NWs, especially in basic medium.
(a) Fe 2p
FeP
(b) P 2p
Fe0
720.0
134
FeP
712.5
726.3
P0
129.5
707.6
129.3
Fe2p1/2
Fe2p3/2
720.4
FeP2
FeP2
134
730 725 720 715 710 705
136 134 132 130 128
Binding Energy (eV)
Binding Energy (eV)
Fig. 4 Fine-scan (a) XPS Fe 2p3/2 and 2p1/2 and (b) P 2p peaks of FeP
and FeP2 NWs. The position of the neural element peak is marked
by a dotted line to clearly delineate the shift.
We performed XPS measurements to investigate the electronic
structures. The peak features are virtually the same for both the
array and freestanding NWs (see the ESI
consistent with previous works.10,12-22 Because the probe depth is a
few nm for the photoelectrons of Fe 2 and P 2 , the XPS peaks
†, Fig. S6) and are
p
p
originate solely from the surface of the FeP and FeP2 NWs. Fig. 4a
shows the Fe 2p1/2 and 2p3/2 peaks for FeP and FeP2 NW arrays. The
peaks of neutral Fe at 720.1 and 707.0 eV are indicated. The 2p3/2
peak of FeP consisted of two bands with peak positions of 707.1
(0.1) and 712.5 (5.5) eV. The value in parentheses represents the
blue shift of each band. The first band mainly originated from the
Fe-P bonding structures. Referring to the data for FeO (Fe2+ at 709
eV) and Fe2O3 (Fe3+ at 711 eV), the second band is assigned to
native (amorphous) oxide layers at the surface, respectively.41 The
negligible blue shift of the Fe-P band indicated the metallic state of
Fe. For the FeP2 NWs, the Fe-P band is observed at 707.6 (0.6),
which is more blue shifted than that of FeP. This is because of the
increased electron withdrawal resulting from the larger amount of
P. Nevertheless, the oxidation number of Fe ions in FeP2 would be
much less than +2. The Fe-O band becomes negligible.
Fig. 3 (a) SEM micrographs and (b) HRTEM images of freestanding
FeP NWs and (c) FeP2 NWs. (d) EDX spectra of FeP and FeP2 NWs,
showing Fe:P= 1:1 and 1:2, respectively.
To support this result, we synthesized freestanding FeP and FeP2
NWs containing no trace of the Fe3O4 phase (see the XRD data in
the ESI†, Fig. S1) and examined their electrocatalytic efficiency. The
NWs were synthesized via a thermal reaction of pre-grown Fe NWs
(synthesized by filament-assisted thermal decomposition of
Fe(CO)5) with PH3. SEM image showed a chain-like wire morphology
(Fig. 3a). HRTEM and FFT images revealed that the single-crystalline
FeP nanocrystals aggregate to form the wire (Fig. 3b). The FeP2 NWs
also have a polycrystalline nature (Fig. 3c). For the single-crystalline
domain of FeP and FeP2, d011 = 2.7 Å (at the zone axis of [211]) and
d110 = 3.7 Å (at the zone axis of [111]) were identified, respectively.
The average diameters of FeP and FeP2 NWs are 60 and 100 nm,
respectively. EDX spectra show Fe:P= 1:1 and 1:2, respectively, for
FeP and FeP2 NWs (Fig. 3d).
Fig. 4b shows the P 2p peaks at 129.5 eV and 129.3 eV for FeP and
FeP2 NWs, respectively, which are red shifted by 0.4 and 0.6 eV
from the neutral peak (129.9 eV for 2p3/2). This band originated
from the negatively charged P ions of the P-Fe bonding structures.
The larger peak shift observed for the FeP2 NWs is caused by the
larger amount of P, which also causes the relatively large blue shift
of the Fe 2
p Fe-P band. The higher energy peak at 134 eV is
ascribed to the P-O bonding structure of (amorphous) oxide forms,
such as phosphate. The FeP2 NWs exhibit a much smaller P-O band
than the FeP NWs. It is concluded that as the P content increases,
the surface oxidation decreases significantly.
The sample (1 mg cm-2) was deposited on a GC electrode, and the
performance was examined at a rotation speed of 1600 rpm. Table
Liu and Rodriguez predicted that Ni2P could be an excellent
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 4 of 5
View Article Online
DOI: 10.1039/C5CC09832G
ARTICLE
Journal Name
13 P. Jiang, Q. Liu, Y. Liang, J. Tian, A. M. Asiri and X. Sun,
Angew. Chem. Int. Ed., 2014, 53, 12855.
14 R. Liu, S. Gu, H. Du and C. M. Li, J. Mater. Chem. A, 2014, 2,
17263.
catalyst for HER using density functional theory calculations. They
suggested that proton-acceptor (P sites) and hydride-acceptor sites
(Ni sites) work in a cooperative manner.42 The same model can be
used to rationalize the FeP and FeP2 NWs studied here. Both Fe and
P are active sites for the HER, functioning as the hydride-acceptor
and proton-acceptor centers, respectively. It was expected that Fe
ions in FeP, being more metallic than those in FeP2, became more
favorable hydride-acceptor sites. However, more negative charged
P anions in FeP2 created the more active proton-acceptor sites. The
higher concentration of the exposed active P ions can also increase
the catalytic activity. Furthermore the rich P composition protects
more effectively the oxidation of metal ions. This probably explains
why the FeP2 NWs exhibit higher HER catalytic activity than the FeP
NWs with a higher stability.
15 J. Tian, Q. Liu, Y. Liang, Z. Xing, A. M. Asiri and X. Sun, ACS
Appl. Mater. Interfaces, 2014, , 20579.
16 J. Jiang, C. Wang, J. Zhang, W. Wang, X. Zhou, B. Pan, K. Tang,
J. Zuo and Q. Yang, J. Mater. Chem. A, 2015, , 449.
6
3
17 S. Han, Y. Feng, F. Zhang, C. Yang, Z. Yao, W. Zhao, F. Qiu, L.
Yang, Y. Yao, X. Zhuang and X. Feng, Adv. Funct. Mater.,
2015, 25, 3899.
18 Z. Zhang, J. Hao, W. Yang, B. Lu and J. Tang, Nanoscale, 2015,
7, 4400.
19 Z. Pu, C. Tang and Y. Luo, Int. J. Hydrogen Energy, 2015, 40
5092.
,
20 H. Du, S. Gu, R. Liu and C. M. Li, Int. J. Hydrogen Energy,
2015, 40, 14272-14278.
21 X. Yang, A. Y. Lu, Y. Zhu, S. Min, M. N. Hedhili, Y. Han, K. W.
In summary, we synthesized FeP and FeP2 NW arrays on large
substrate areas by reacting pre-grown vertically aligned Fe2O3 NWs
(on Fe foils) and PH3. The FeP and FeP2 NWs exhibit excellent
performance for electrocatalytic HER in both strong acidic and basic
aqueous solutions. The Tafel slopes are 39 and 37 mV dec-1 in 0.5 M
H2SO4 and 75 and 67 mV dec-1 in 1 M KOH, respectively. In addition,
we also synthesized freestanding FeP and FeP2 NWs by
phosphidation of pre-grown Fe NWs and found that the Tafel slopes
are 66 and 40 mV dec-1 in 0.5 M H2SO4, respectively. The FeP2 NWs
exhibit higher electrocatalytic efficiency and better durability than
the FeP NWs. XPS analysis revealed the more negative charged P
anions for FeP2, which can create the more active proton-acceptor
sites. The richer P composition protects effectively the oxidation of
metal ions, which promises a higher stability of catalytic activity.
Therefore, the FeP2 NW catalyst that showed excellent performance
is a promising material for the development of water-splitting cells
able to compete with conventional hydrogen sources.
Huang and L. J. Li, Nanoscale, 2015, 7, 10974.
22 Y. Yam, B. Y. Xia, X. Ge, Z. Liu, A. Fisher and X. Wang, Chem.
Eur. J., 2015, 21, DOI: 10.1002/chem.201503777.
23 E. J. Popczum, C. G. Read, C. W. Roske, N. S. Lewis and R. E.
Schaak, Angew. Chem. Int. Ed., 2014, 53, 5427.
24 Q. Liu, J. Tian, W. Cui, P. Jiang, N. Cheng, A. M. Asiri and X.
Sun, Angew. Chem. Int. Ed., 2014, 126, 6828.
25 J. Tian, Q. Liu, A. M. Asiri and X. Sun, J. Am. Chem. Soc., 2014,
136, 7587.
26 Y. Yang, H. Fei, G. Ruan and J. M. Tour, Adv. Mater., 2015, 27
3175.
27 J. F. Callejas, C. G. Read, E. J. Popczun, J. M. McEnaney and R.
E. Schaak, Chem. Mater., 2015, 27, 3769.
28 E. J. Popczum, J. R. McKone, C. G. Read, A. J. Biacchi, A. M.
Wiltrout, N. S. Lewis and R. E. Schaak, J. Am. Chem. Soc.,
2013, 135, 9267.
29 A. R. J. Kucernak and V. N. N. Sundaram, J. Mater. Chem. A,
2014, 2, 17435.
30 A. B. Laursen, K. R. Patraju, M. J. Whitaker, M. Retuerto, T.
Sarkar, N. Yao, K. V. Ramanujachary, M. Greenblatt and G. C.
,
Dismukes, Energy Environ. Sci., 2015,
31 Y. Pan, Y. Liu, J. Zhao, K. Yang, J. Liang, D. Liu, W. Hu, D. Liu,
Y. Liu, C. Liu, J. Mater. Chem. A, 2015, , 1656.
8, 1027.
Notes and references
3
32 X. Wang, Y. V. Kolen’ko, X. Bao, K. Kovnir and L. Liu, Angew.
Chem. Int. Ed., 2015, 54, 8188-8192.
33 M. Ledendecker, S. K. Calderón, C. Papp, H. Steinrück, M.
1
2
3
4
T. F. Jaramillo, K. P. Jørgensen, J. Bonde and J. H. Nielsen,
Science, 2007, 317, 100.
Y. Li, H. Wang, L. Xie, Y. Liang, G. Hong and H. Dai, J. Am.
Chem. Soc., 2011, 133, 7296.
H. I. Karunadasa, E. Montalvo, Y. Sun, M. Majda, J. R. Long
and C. J. Chang, Science, 2012, 335, 698.
D. Voiry, H. Yamaguchi, J. Li, R. Silva, D. C. B. Alves, T. Fujita,
M. Chen, T. Asefa, V. B. Shenoy, G. Eda and M. Chhowalla,
Nat. Mater., 2013, 12, 850.
Antonietti and M. Shaldom, Angew. Chem. Int. Ed., 2015, 54
12361.
,
34 J. Tian, Q. Liu, N. Cheng, A. M. Asiri and X. Sun, Angew.
Chem. Int. Ed., 2014, 53, 9577.
35 Z. Xing, Q. Liu, A. M. Asiri and X. Sun, Adv. Mater., 2014, 26
5702.
,
36 X. Chen, D. Wang, Z. Wang, P. Zhou, Z. Wu, F. Jiang, Chem.
Commun., 2014, 50, 11683.
37 J. Kibsgaard and T. F. Jaramillo, Angew. Chem. Int. Ed., 2014,
53, 14433.
38 T. Wang, K. Du, W. Liu, Z. Zhu, Y. Shao and M. Li, J. Mater.
Chem. A, 2015, 3, 4368.
39 P. Xiao, W. Chen, X. Wang, Adv. Energy Mater., 2015,
doi:10.1002/aenm.201500985.
40 C. H. Kim, H. J. Chun, D. S. Kim, S. Y. Kim, J. Park, J. Y. Moon,
G. Lee, J. Yoon, Y. Jo, M. H. Jung, S. I. Jung and C. J. Lee, Appl.
Phys. Lett., 2006, 89, 223103.
5
6
7
X. Huang, Z. Zeng, S. Bao, M. Wang, X. Qi, Z. Fan and H.
Zhang, Nat. Commun., 2013,
Y. Zheng, Y. Jiao, Y. Zhu, L. H. Li, Y. Han, Y. Chen, A. Du, M.
Jaroniec and S. Z. Qiao, Nat. Commun., 2014, , 3783.
4, 1444.
5
C. G. Morales-Guio, L. Stern and X. Hu, Chem. Soc. Rev.,
2014, 43, 6555.
X. Zou and Y. Zhang, Chem. Soc. Rev., 2015, 44, 5148.
Y. Xu, R. Wu, J. Zhang, Y. Shi and B. Zhang, Chem. Commun.,
2013, 49, 6656.
8
9
10 Y. Liang, Q. Liu, A. M. Asiri, X. Sun and Y. Luo, ACS Catal.,
2014, , 4065.
11 J. F. Callejas, J. M. McEnaney, C. G. Read, J. C. Crompton, A. J.
Biacchi, E. J. Popczun, T. R. Gordon, N. S. Lewis and R. E.
Schaak, ACS Nano, 2014, 8, 11101.
41 A. P. Grosvenor, B. A. Kobe, M. C. Biesinger and N. S.
McIntyre, Surf. Interface Anal., 2004, 36, 1564.
4
42 P. Liu and J. A. Rodriquez, J. Am. Chem. Soc., 2005, 127
14871.
,
12 Z. Zhang, B. Lu, J. Hao, W. Yang and J. Tang, Chem. Commun.,
2014, 50, 11554.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 5 of 5
View Article Online
DOI: 10.1039/C5CC09832G
Journal Name
ARTICLE
Entry for the Table of Contents
Text for Table of Contents
FeP and FeP2 nanowires exhibit excellent
electrocatalytic abilities toward hydrogen
evolution from water splitting.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins