Mechanical mixtures of metal oxides and phosphorus pentoxide as novel precursors for the synthesis of transition-metal phosphides

Article abstract of DOI:10.1039/c5dt03671b

This study presents a new type of precursor, mechanical mixtures of metal oxides (MOs) and phosphorus pentoxide (P₂O₅) are used to synthesize Ni₂P, Co₂P and MoP phosphides by the H₂ reduction method. In addition, this is first report of common solid-state P₂O₅ being used as a P source for the synthesis of metal phosphides. The traditional precursors are usually prepared via a complicated preparation procedure involving dissolution, drying and calcination steps. However, these novel MOs/P₂O₅ precursors can be obtained only by simple mechanical mixing of the starting materials. Furthermore, unlike the direct transformation from amorphous phases to phosphides, various specific intermediates were involved in the transformation from MOs/P₂O₅ to phosphides. It is worthy to note that the dispersions of Ni₂P, Co₂P and MoP obtained from MOs/P₂O₅ precursors were superior to those of the corresponding phosphides prepared from the abovementioned traditional precursors. It is suggested that the morphology of the as-prepared metal phosphides might be inherited from the corresponding MOs. Based on the results of XRD, XPS, SEM and TEM, the formation pathway of phosphides can be defined as MOs/P₂O₅ precursors → complex intermediates (metals, metal phosphates and metal oxide-phosphates) → metal phosphides.

Full text of DOI:10.1039/c5dt03671b

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PAPER
Mechanical mixtures of metal oxides and
phosphorus pentoxide as novel precursors for
the synthesis of transition-metal phosphides†
Cite this: Dalton Trans., 2016, 45,
1225
Lijuan Guo,a Yu Zhaob and Zhiwei Yao*b
This study presents a new type of precursor, mechanical mixtures of metal oxides (MOs) and phosphorus
pentoxide (P2O5) are used to synthesize Ni2P, Co2P and MoP phosphides by the H2 reduction method. In
addition, this is first report of common solid-state P2O5 being used as a P source for the synthesis of
metal phosphides. The traditional precursors are usually prepared via a complicated preparation pro-
cedure involving dissolution, drying and calcination steps. However, these novel MOs/P2O5 precursors
can be obtained only by simple mechanical mixing of the starting materials. Furthermore, unlike the direct
transformation from amorphous phases to phosphides, various specific intermediates were involved in
the transformation from MOs/P2O5 to phosphides. It is worthy to note that the dispersions of Ni2P, Co2P
and MoP obtained from MOs/P2O5 precursors were superior to those of the corresponding phosphides
prepared from the abovementioned traditional precursors. It is suggested that the morphology of the as-
prepared metal phosphides might be inherited from the corresponding MOs. Based on the results of XRD,
XPS, SEM and TEM, the formation pathway of phosphides can be defined as MOs/P2O5 precursors →
complex intermediates (metals, metal phosphates and metal oxide-phosphates) → metal phosphides.
Received 19th September 2015,
Accepted 1st December 2015
DOI: 10.1039/c5dt03671b
www.rsc.org/dalton
sition of single-source precursors in solution,28 microwave or
solvothermal synthesis,29,30 and chemical vapor deposition.31
1. Introduction
Transition metal phosphides have attracted much attention in The main phosphorus sources in these syntheses can be
the past 20 years, owing to their unique properties and poten- divided into four groups:17 (i) tri-n-octylphosphine (TOP),
tial applications in the fields of photonics, electronics, mag- alkyl- and aryl-phosphines, (ii) elemental white phosphorus
netism, and catalysis.1–4 In particular, they have been used as and red phosphorus, (iii) P(SiMe3)3 and single-source precur-
excellent catalysts in many reactions such as hydrogenation sors and (iv) other phosphorus sources such as diammonium/
and hydrotreating,5–8 H2 evolution reaction,2,9,10 N2H4 sodium hydrogen phosphate, PH3, and PCl3. However, most of
decomposition,11–13 and NO reduction.14 It is worthy to note these phosphorus sources (TOP, PH3, P(SiMe3)3 and P4) are
that Ni2P phosphide is reported to be a very efficient hydro- highly toxic, and cannot afford the currents requirements for
desulfurization catalyst in terms of both activity and resistance green chemistry. In general, diammonium hydrogen phos-
to poisoning.15,16 Thus, extensive effort has been focused on phate ((NH4)2HPO4) was recognized as an environmentally-
developing methods for synthesizing metal phosphides.
friendly phosphorus source for the preparation of phosphide
There are a variety of methods reported regarding the catalysts via the H2 temperature-programmed reduction
preparation of metal phosphides,17 including direct reduction (H2-TPR) method.19 Nevertheless, there were two shortcomings
of phosphate in H2 or H2 plasma,15,18,19 reaction of metal/ on the use of (NH4)2HPO4 as a phosphorus source in this syn-
metal oxide with PH3,20 solid-state reaction methods using thetic route. On the one hand, the preparation of precursors
white or red phosphorus,21,22 decomposition of high-boiling for phosphides involved complicated steps as follows:32 the
point tri-n-octyrphosphine (TOP) or P(SiMe3)3,23–27 decompo- dissolution of (NH4)2HPO4 and metal salts, and subsequent
drying and calcination. On the other hand, the as-prepared
precursors and resulting intermediates from them were almost
aCollege of Basic Medical Sciences, Changsha Medical University, Changsha,
410219, P.R. China
always amorphous so their structural phases were difficult to
determine. Therefore, the pathway of reduction for this type of
precursor into metal phosphides has not been clarified com-
pletely yet. The reduction process was still represented by the
following equation: zMOx + POy + (nx + y)H2 → MzP + (nx + y)
H2O.18,19,33,34
bCollege of Chemistry, Chemical Engineering and Environmental Engineering,
Liaoning Shihua University, Fushun, 113001, P.R. China.
E-mail: mezhiwei@163.com
†Electronic supplementary information (ESI) available. See DOI: 10.1039/
c5dt03671b
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In this study, we described a modified H2 reduction
method for synthesizing metal phosphides, in which the pre-
cursors for phosphides were obtained simply by mechanical
mixing of metal oxides (MOs) and P2O5. Moreover, to our
knowledge, this is the first time that this type of common P2O5
has been used as a phosphorus source for metal phosphide
synthesis. The pathway for the transformations of MOs/P2O5
mixtures into phosphides can be proposed by combining XRD,
XPS, SEM and TEM studies.
2. Experimental
2.1 Sample preparation
In a typical experiment, transition metal phosphides were pre-
pared in two steps. First, the precursors for Ni2P, Co2P and
MoP were prepared by the mechanical mixing method through
co-grinding P2O5 and the corresponding metal oxides (MOs)
with stoichiometric M/P ratios. The MOs were obtained by the
calcination of metal salts (Ni(NO3)2·6H2O, Co(NO3)2·6H2O)
and (NH4)6Mo7O24·4H2O) at 500 °C for 3 h in a muffle furnace.
The precursors were heated in a quartz reactor under a flow of
H2 (50 ml min−1). The temperature was increased linearly at a
rate of 10 °C min−1 and then maintained at 650 °C (for Ni2P
and Co2P) or 750 °C (for MoP) for 1 h, followed by cooling to
room temperature (RT) under H2 flow, and then passivated at
RT in a stream of 0.5% O2/Ar for 2 h. To clarify the formation
process, the effect of reduction temperature was investigated.
The precursors were reduced from 400 to 650 °C for Ni2P, 500
to 650 °C for Co2P, and 500 to 750 °C for MoP. The resultant
products were designated as Ni–H2-400, -500, -600 and -650,
Co–H2-500, -600 and -650, and Mo–H2-500, -650 and -750. In
addition, these precursors were also heated in Ar flow
(50 ml min−1) at 500 °C, and the resulting samples were desig-
nated as Ni–Ar-500, Co–Ar-500 and Mo–Ar-500.
Fig. 1 XRD patterns of Ni2P, Co2P and MoP synthesized from their
MOs/P2O5 precursors.
metal oxide-phosphates or other phosphide phases, indicating
that the as-prepared Ni2P, Co2P and MoP materials were phase-
pure. In addition, the results indicated that the simple mech-
anical mixing method was effective enough to ensure a
uniform distribution of MOs and P2O5.
To further confirm the formation of Ni2P, Co2P and MoP
phosphides, subsequent XPS analysis was conducted. Fig. 2
shows the XPS spectra of the P 2p, Ni 2p, Co 2p, Mo 3d and
O 1s regions for the phosphides prepared from MOs/P2O5 pre-
cursors. On the basis of curve fitting, the binding energies of
P 2p3/2, Ni 2p3/2, Co 2p3/2, Mo 3d5/2 and O 1s as well as the
surface element concentrations and distribution of these
corresponding species are listed in Tables 1 and 2. Because the
as-prepared metal phosphides were usually passivated before
exposure to air, the surface regions of all the samples should
be dominated by oxidized species and the underlying phos-
phided species.35,36 In the case of the P 2p XPS spectra, two
P 2p peaks were observed at 129.2–129.4 and 133.1–133.5 eV,
which were attributed to the phosphided species (Pδ−) and oxi-
dized species (P5+).37 The results demonstrated the formation
of phosphides of Ni, Co and Mo. For the Ni2P sample, two
peaks were observed at 853.2 and 856.4 eV in the Ni 2p3/2
2.2 Sample characterizations
X-Ray diffraction (XRD) analysis of the samples was performed
by a X’Pert Pro MPD diffractometer equipped with a Cu Kα
source. X-ray photoelectron spectroscopy (XPS) study was con-
ducted by a Kratos Axis ultra (DLD) equipped with an Al Kα
X-ray source. Charging effects were corrected on the basis of
adventitious carbon (284.6 eV) referencing. The morphology
of the samples was characterized by scanning electron
microscopy (SEM, Hitachi S-4800) and transmission electron
microscopy (TEM, Philips Tecnal 10).
region, corresponding to the Niδ+ species in Ni2P and Ni2+ 38
.
For Co2P sample, one peak was observed at 781.2 eV in the
Co 2p3/2 region, which was assigned to Co2+;39 however, no
peak was visible at around 778.3 eV for Coδ+ species40 in Co2P.
This was probably due to the fact that the Coδ+ species was so
low in concentration that its corresponding peak area was over-
shadowed by that of Co2+ species. This suggested that there
was a thicker passivation layer on the surface of the Co2P
sample. For the MoP sample, the Mo 3d5/2 peaks at 228.1,
229.3 and 232.4 eV were ascribed to the Moδ+ species in MoP,
Mo4+ and Mo6+, respectively.40 The O 1s XPS spectra consisted
of two peaks at 533.1–533.4 and 531.4–531.9 eV, which were
typically assigned to the bridging oxygen linking two phos-
phate groups together (P–O–P) and the non-bridging oxygen
terminating the phosphates (–POx), respectively.41 The results
3. Results and discussion
3.1 Microstructural characterization
Fig. 1 shows the XRD patterns of metal phosphides syn-
thesized by reduction of mixtures of MOs and P2O5 in H2. The
peak positions were consistent with previous findings for the
synthesis of Ni2P, Co2P and MoP. There were no diffraction
peaks that can be assigned to metal phosphates, metal oxides,
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Table 2 Binding energies for species on the surfaces of the Ni2P, Co2P
and MoP samples obtained in this study
Sample
Binding energy (eV)
Ni 2p3/2
P 2p3/2
Pδ−
O 1s
Niδ+
Ni2+
P5+
P–O–P
–POx
Ni2P
Co2P
MoP
853.2
856.4
129.2
133.5
533.1
O 1s
531.5
Co 2p3/2
P 2p3/2
Coδ+
Co2+
Pδ−
P5+
P–O–P
–POx
—
781.2
129.3
133.1
533.4
O 1s
531.9
Mo 3d5/2
P 2p3/2
Moδ+
228.1
Mo4+/Mo6+
229.3/232.4
Pδ−
P5+
P–O–P
–POx
129.4
133.3
533.1
531.4
indicated that the passivation-induced oxidized species were
metal phosphates rather than metal oxides because no peaks
were observed at about 529.7, 530.2 and 530.7 eV for NiO, CoO
and MoOx, respectively.42–44
Finally, the morphologies of Ni2P, Co2P and MoP (hereafter
denoted as S–Ni2P, S–Co2P and S–MoP, respectively) obtained
from solid mixtures (MOs and P2O5) were characterized by SEM
and TEM. For the sake of comparison, Ni2P, Co2P and MoP
(hereafter denoted as L–Ni2P, L–Co2P and L–MoP, respectively)
were prepared from traditional raw materials (liquid mixtures of
metal salts and (NH4)2HPO4) described elsewhere,38 and their
morphologies were also investigated by means of SEM (see
ESI†). It can be observed from SEM images (Fig. 3a–c) that the
morphologies of S–Ni2P, S–Co2P and S–MoP were similar and
they were composed of dispersed particles. It was noteworthy
that the dispersions of these particles were on the nanoscale for
the Co2P and MoP samples. These results were in good agree-
ment with the observed TEM images (Fig. 4). In addition, the
HRTEM images clearly showed that the measured spacings
between lattice fringes of 0.22, 0.43 and 0.32 nm were consist-
ent with the d-spacings of the (111) plane of Ni2P (card no. 65-
1989), the (101) plane of Co2P (card no. 32-0306) and the (001)
plane of MoP (card no. 65-6487), respectively. On the contrary,
the L–Ni2P and L–Co2P samples consisted of particles with
serious conglomeration and the L–MoP sample consisted of
submicrometer-sized MoP thin sheets (see Fig. S1a–c†), which
was in accord with the SEM results reported by others.38,45–47 It
was reported that the morphology of metal phosphides
depended highly on the used metal oxide precursors.48,49 There-
fore, the SEM images of these MOs (NiO, Co3O4 and MoO3)
used in the study were shown in Fig. S2a–c.† It was found that
the morphologies of S–Ni2P, S–Co2P and S–MoP samples were
indeed similar to those of corresponding MOs. The results
suggested that the morphology of the metal phosphides
obtained using MOs/P2O5 mixtures as precursors might be con-
trolled by adjusting the morphology of the MOs. Further investi-
gations about this aspect are in progress.
Fig. 2 XPS spectra of P 2p, Ni 2p, Co 2p, Mo 3d and O 1s in (a) Ni2P,
(b) Co2P and (c) MoP.
Table 1 Surface element concentrations as determined by XPS
Element concentration (at%)
Sample
C 1s
O 1s
P 2p
Ni 2p, Co 2p, Mo 3d
Ni2P
Co2P
MoP
35.03
63.09
45.53
32.99
23.81
34.75
14.00
7.66
8.33
17.98
5.44
11.39
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Fig. 4 Low and high resolution TEM images of (a) S–Ni2P, (b) S–Co2P
and (c) S–MoP.
Fig. 3 SEM images of (a) S–Ni2P, (b) S–Co2P and (c) S–MoP.
of the products obtained in the study are listed in Table 3.
Fig. 5 shows the XRD patterns of the solid mixture precursors
treated at 500 °C in the absence of H2. After heating these
solid mixtures at 500 °C in Ar, Co3O4 and MoO3 can react with
P2O5 to produce cobalt phosphates (Co2P2O7 (main peaks at 2θ
of 29.6°, 30.1° and 35.2°) and Co2P4O12 (main peaks at 2θ of
14.3° and 29.6°)) and (MoO2)(PO3)2 (main peaks at 2θ of 11.5°,
16.6°, 23.1°, 24.0° and 26.2°, corresponding to the (100), (110),
(200), (020) and (210) planes). In the case of NiO/P2O5, a set of
peaks marked with rhombuses were found, but they cannot be
assigned to any (known) Ni oxides, Ni phosphates or Ni oxide-
3.2 Formation pathway of phosphides
To give insights into the formation process of phosphides
obtained from mixtures of NiO/P2O5, Co3O4/P2O5 and MoO3/
P2O5, some intermediate samples were characterized by XRD.
In view of the fact that the temperature-dependent reduction
process usually involved simultaneously two aspects (heat-
treatment and reduction), the treatments of these mixture pre-
cursors in the absence/presence of H2 should be investigated.
In addition, for the sake of comparison, the phase structures
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Table 3 Phase structures of the samples obtained in this study
Sample
XRD phases
JCPDS cards
Ni–Ar-500
Co–Ar-500
Mo–Ar-500
Ni–H2-400
Ni–H2-500
Ni–H2-600
Ni–H2-650
Co–H2-500
Co–H2-600
Co–H2-650
Mo–H2-500
Mo–H2-650
Mo–H2-750
NiO, NiOxPOy
Co3O4, Co2P2O7, Co2P4O12
(MoO2)(PO3)2
NiO, Ni, NiOxPOy
Ni12P5, Ni2P
Ni2P
Ni2P
Co, Co2P2O7
Co2P
Co2P
MoO2
MoP2O7
MoP
89-7131, —
09-0418, 49-1091, 40-0068
74-1389
89-7131, 65-0380, —
74-1381, 65-1989
65-1989
65-1989
15-0806, 49-1091
65-2380
65-2380
78-1069
84-1794
65-6487
Fig. 6 XRD patterns of the NiO/P2O5 precursor for Ni2P treated at
different temperatures in H2 flow.
Fig. 5 XRD patterns of the mixture precursors (NiO/P2O5, Co3O4/P2O5
and MoO3/P2O5) treated at 500 °C in Ar.
phosphates. Thus, it can be inferred from the XRD that NiO
can react with P2O5 to yield an unknown compound
(NiOxPOy). These results indicated that all the above men-
tioned MOs can be transformed into metal phosphates or
metal oxide-phosphates when the solid mixtures were heated
in the absence of H2. However, the absence of diffraction
peaks of phosphorus oxides in Fig. 5 was probably due to their
amorphous forms or high dispersion on the solid surface.50,51
Fig. 6–8 shows the XRD patterns of the solid mixture pre-
cursors treated at different temperatures in a H2 atmosphere.
In the case of the NiO/P2O5 sample, it can be observed from
Fig. 6 that at 400 °C, the precursor was transformed into a
mixture of NiO, NiOxPOy and Ni metal (main peaks at 2θ of
44.3 and 51.7, indexed to the (111) and (200) planes, respect-
ively). The result indicated that a portion of NiO was reduced
by H2 to Ni; however, it interacted with P2O5 to produce
NiOxPOy during heat-treatment process (see Fig. 5). When the
temperature was increased to 500 °C, the peaks for NiO, Ni
and NiOxPOy disappeared or weakened, and there were new
peaks corresponded to Ni12P5 (main peaks at 2θ of 32.7°,
38.4°, 41.8°, 47.0° and 49.0°, indexed to (310), (112), (400),
(240) and (312) planes, respectively) and Ni2P (main peaks at
Fig. 7 XRD patterns of the Co3O4/P2O5 precursor for Co2P treated at
different temperatures in H2 flow.
Fig. 8 XRD patterns of the MoO3/P2O5 precursor for MoP treated at
different temperatures in H2 flow.
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Scheme 1 Schematic of the phases formed during reduction of the MOs/P2O5 precursors.
2θ of 40.7°, 44.6°, 47.4°, 54.2° and 55.0°, due to the (111),
In addition, the background features to the XRD patterns
(201), (210), (300) and (211) planes, respectively) phases. With (Fig. 6–8), especially for those of Ni–H2-400 and Mo–H2-500,
a further increase in temperature (≥600 °C), all the Ni-contain- appeared consistent with some amorphous components. Some
ing species were converted to Ni phosphides in H2 flow and phosphorus oxides and metal (metal–oxide) phosphates were
there was an clear phase transformation (Ni12P5 → Ni2P) in the reported to be amorphous and were usually involved in the
sample just as the observation reported before,35,36 and then traditional precursors for the synthesis of phosphides via the
phase-pure Ni2P can be obtained as a final product.
H2-TPR method,6,50,51 thus it was reasonable to deduce that in
In the case of Co3O4/P2O5 sample (Fig. 7), a mixture of Co the present study the reactions between P2O5 and metal oxides
metal (main peaks at 2θ of 44.4° and 51.6°) and Co2P2O7 might also yield a small amount of these amorphous phases.
(main peaks at 2θ of 29.6° and 30.1°) was obtained after However, at higher temperatures (≥650 °C), the amorphous
heating the precursor at 500 °C in H2, indicating that a portion metal (metal–oxide) phosphate phases and amorphous phos-
of Co3O4 was reduced to Co metal, and the rest was trans- phorus oxide/metal oxide mixtures were easily reduced by H2
formed into cobalt phosphate (Co2P2O7) due to its reactivity to produce metal phosphides,6 which agreed with the XRD
with P2O5 (see Fig. 5). When the temperature was increased to results that the amorphous backgrounds disappeared on the
600 °C, those Co-containing species obtained at 500 °C were XRD patterns of Ni–H2-650, Co–H2-650 and Mo–H2-750. More-
completely converted to the desired product Co2P. The inten- over, the clear lattice fringes in the HRTEM images (Fig. 4)
sity of the Co2P peaks increased with temperature, and the further confirmed the high crystalline nature of the syn-
well crystalline Co2P (main peaks at 2θ of 40.7°, 41.0°, 42.1°, thesized metal phosphides.
43.3°, 44.1°, 48.7°, 50.4°, 52.0° and 56.2°, indexed to the (112),
(210), (202), (211), (103), (013), (301), (020) and (302) planes, phides involved mixing of MOs and P2O5 and subsequent
respectively) can be obtained at 650 °C. reduction with H2. Based on the results of XRD, XPS, SEM and
The syntheses utilized in this study to prepare metal phos-
As for the MoO3/P2O5 sample (see Fig. 8), it was clear that TEM, the investigation of the synthesis processes (see
the diffraction peaks for MoO2 (main peaks at 2θ of 26.0°, Scheme 1) clearly showed that MOs can be reduced at relatively
36.7°, 37.0°, 37.2°, 53.0° and 53.1°, indexed to the (011), low temperatures to corresponding metals or low-valence
(−202), (020), (002), (−213) and (−222) planes, respectively) can oxides, at the same time, MOs can also be reacted with P2O5 to
be observed when the sample was heated at 500 °C in H2 flow, form metal phosphates or metal oxide-phosphates. A small
but there were no peaks for the (MoO2)(PO3)2 phase mentioned portion of these phosphates still remained amorphous.
above in Fig. 5, indicating that MoO3 was preferentially con- Finally, these metal-containing species (metal oxides, metals,
verted to low-valence Mo oxide rather than Mo oxide-phos- metal phosphates and metal oxide-phosphates) were converted
phate at 500 °C in the presence of H2. With an increase of the to metal phosphides at relatively high temperatures. The for-
temperature to 650 °C, no reflections for Mo phosphide were mation pathway of phosphides using MOs/P2O5 mixtures as
found. However, conversely, MoO2 was transformed into precursors can be clarified as MOs/P2O5 precursors → complex
MoP2O7 (main peaks at 2θ of 19.3°, 22.4°, 25.0°, 27.5°, 31.8° intermediates (metals, metal phosphates and metal oxide-
and 37.5°, corresponding to the (111), (200), (210), (211), (220) phosphates) → metal phosphides.
and (311) planes) instead of being further reduced to
The route presented showed a number of advantages in
Mo metal because the reduction of MoO2 required a higher comparison to the traditional H2-TPR method using
temperature (>700 °C).52 Fortunately, when the temperature (NH4)2HPO4 and metal salts as starting materials. The precur-
was further increased to 750 °C, the peaks for MoP2O7 dis- sors used in the route were obtained simply by mechanical
appeared, and main diffraction peaks at 28.0°, 32.1°, 43.1°, mixing of metal oxides (MOs) and P2O5, instead of dissolution,
57.3°, 64.9°, 67.6°, 74.2° and 85.7° were observed, corres- drying and calcination steps involved in the preparation pro-
ponding to the (001), (100), (101), (110)/(002), (111), (200)/ cedure for traditional precursors; the route favored the for-
(102), (201) and (112) planes of MoP.
mation of phosphides via various specific intermediates,
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which can be helpful to understand the formation mechan- 11 L. Ding, Y. Shu, A. Wang, M. Zheng, L. Li, X. Wang and
ism; the dispersions of the phosphides obtained from MOs/ T. Zhang, Appl. Catal., A, 2010, 385, 232–237.
P2O5 precursors were superior to those of phosphides prepared 12 R. Cheng, Y. Shu, M. Zheng, L. Li, J. Sun, X. Wang and
from the traditional precursors. Finally, it was suggested that T. Zhang, J. Catal., 2007, 249, 397–400.
the route might be feasible for large scale preparation of 13 M. Zheng, Y. Shu, J. Sun and T. Zhang, Catal. Lett., 2008,
phosphides and this aspect will be investigated in the future.
121, 90–96.
14 Z. W. Yao, H. Dong and Y. Shang, J. Alloys. Compd., 2009,
474, L10–L13.
15 S. T. Oyama, J. Catal., 2003, 216, 343–352.
16 R. Cheng, Y. Shu, M. Zheng, L. Li, J. Sun, X. Wang and
T. Zhang, J. Catal., 2007, 249, 397–400.
4. Conclusions
In summary, we developed a new MOs/P2O5 precursors for the
synthesis of Ni2P, Co2P and MoP phosphides via the H2 17 S. Carenco, D. Portehault, C. Boissière, N. Mézailles and
reduction method. Compared with the traditional precursors C. Sanchez, Chem. Rev., 2013, 113, 7981–8065.
obtained from metal salts and (NH4)2HPO4 via dissolution, 18 A. Wang, M. Qin, J. Guan, L. Wang, H. Guo, X. Li, Y. Wang
drying and calcination, this new type of precursor was pre-
pared only by simple mechanical mixing of starting materials.
and R. Prins, Angew. Chem., Int. Ed., 2008, 120, 6141–
6143.
Furthermore, the formation pathway of phosphides using the 19 J. Guan, Y. Wang, M. Qin, Y. Yang, X. Li and A. Wang,
precursors can be proposed as the MOs/P2O5 precursors shift- J. Solid State Chem., 2009, 182, 1550–1555.
ing to the phosphide products via metal, metal phosphate and 20 S. Yang, C. Liang and R. Prins, J. Catal., 2006, 237, 118–
metal oxide-phosphate intermediates. In addition, it was 130.
found that the dispersions of Ni2P, Co2P and MoP obtained 21 Y. Xie, H. L. Su, X. F. Qian, X. M. Liu and Y. T. Qian, J. Solid
from MOs/P2O5 precursors were superior to those of the State Chem., 2000, 149, 88–91.
corresponding phosphides prepared from the traditional pre- 22 Y. Ni, L. Jin and J. Hong, Nanoscale, 2011, 3, 196–200.
cursors. This was because the morphology of as-prepared 23 J. Park, B. Koo, K. Y. Yoon, Y. Hwang, M. Kang, J.-G. Park
metal phosphides might be inherited from corresponding
MOs.
and T. Hyeon, J. Am. Chem. Soc., 2005, 127, 8433–8440.
24 A. E. Henkes and R. E. Schaak, Chem. Mater., 2007, 19,
4234–4242.
25 E. Muthuswamy, G. H. L. Savithra and S. L. Brock, ACS
Nano, 2011, 5, 2402–2411.
26 L. Li and P. Reiss, J. Am. Chem. Soc., 2008, 130, 11588–
11589.
27 W.-S. Ojo, S. Xu, F. Delpech, C. Nayral and B. Chaudret,
Angew. Chem., Int. Ed., 2012, 51, 738–741.
Acknowledgements
We acknowledge the financial support from the National
Natural Science Foundation of China (No. 21276253).
28 W. Maneeprakorn, C. Q. Nguyen, M. A. Malik, P. O’Brien
and J. Raftery, Dalton Trans., 2009, 2103–2108.
29 S. Liu, X. Liu, L. Xu, Y. Qian and X. Ma, J. Cryst. Growth,
2007, 304, 430–434.
Notes and references
1 A.-M. Alexander and J. S. J. Hargreaves, Chem. Soc. Rev.,
2010, 39, 4388–4401.
30 X. Hu and J. C. Yu, Chem. Mater., 2008, 20, 6743–6749.
2 E. J. Popczun, J. R. McKone, C. G. Read, A. J. Biacchi, 31 A. Panneerselvam, M. A. Malik, M. Afzaal, P. O’Brien and
A. M. Wiltrout, N. S. Lewis and R. E. Schaak, J. Am. Chem.
Soc., 2013, 135, 9267–9270.
3 K. Y. Yoon, Y. Jang, J. Park, Y. Hwang, B. Koo, J.-G. Park
and T. Hyeon, J. Solid State Chem., 2008, 181, 1609–1613.
M. Helliwell, J. Am. Chem. Soc., 2008, 130, 2420–2421.
32 X. Wang, P. Clark and S. T. Oyama, J. Catal., 2002, 208,
321–331.
33 I. I. Abu and K. J. Smith, J. Catal., 2006, 241, 356–366.
4 X. C. Jiang, Q. H. Xiong, S. Nam, F. Qian, Y. Li and 34 V. Zuzaniuk and R. Prins, J. Catal., 2003, 219, 85–96.
C. M. Lieber, Nano Lett., 2007, 7, 3214–3218.
5 C. Stinner, R. Prins and Th. Weber, J. Catal., 2000, 191,
438–444.
6 X. Wang, P. Clark and S. T. Oyama, J. Catal., 2002, 208,
321–331.
35 Z. Yao, G. Wang, Y. Shi, Y. Zhao, J. Jiang, Y. Zhang and
H. Wang, Dalton Trans., 2015, 44, 14122–14129.
36 Z. Yao, M. Li, X. Wang, X. Qiao, J. Zhu, Y. Zhao, G. Wang,
J. Yin and H. Wang, Dalton Trans., 2015, 44, 5503–5509.
37 A. W. Burns, A. F. Gaudette and M. E. Bussell, J. Catal.,
2008, 260, 262–269.
7 Q. Guan and W. Li, J. Catal., 2010, 271, 413–415.
8 J. A. Cecilia, A. Infantes-Molina, E. Rodríguez-Castellón and 38 Q. Guan, X. Cheng, R. Li and W. Li, J. Catal., 2013, 299,
A. Jiménez-López, Appl. Catal., B, 2009, 92, 100–113. 1–9.
9 E. J. Popczun, C. G. Read, C. W. Roske, N. S. Lewis and 39 S. S.-Y. Lin, D. H. Kim, M. H. Engelhard and S. Y. Ha,
R. E. Schaak, Angew. Chem., Int. Ed., 2014, 126, 5531–5534. J. Catal., 2010, 273, 229–235.
10 L. Feng, H. Vrubel, M. Bensimon and X. Hu, Phys. Chem. 40 J. Chen, H. Shi, L. Li and K. Li, Appl. Catal., B, 2014, 144,
Chem. Phys., 2014, 16, 5917–5921.
870–884.
This journal is © The Royal Society of Chemistry 2016
Dalton Trans., 2016, 45, 1225–1232 | 1231

View Article Online
Paper
Dalton Transactions
41 R. Heuberger, A. Rossi and N. D. Spencer, Tribol. Lett., 47 R. Cheng, Y. Shu, L. Li, M. Zheng, X. Wang, A. Wang and
2007, 25, 185–196.
T. Zhang, Appl. Catal., A, 2007, 316, 160–168.
48 Q. Guan and W. Li, J. Catal., 2010, 271, 413–
415.
49 Z. Yao, H. Hai, Z. Lai, X. Zhang, F. Peng and C. Yan, Top.
Catal., 2012, 55, 1040–1045.
42 Z. Qi and W. Lee, Tribol. Int., 2010, 43, 810–814.
43 S. Survilienė, V. Jasulaitienė, A. Češūnienė and A. Lisowska-
Oleksiak, Solid State Ionics, 2008, 179, 222–227.
44 J. A. Schaidle, A. C. Lausche and L. T. Thompson, J. Catal.,
2010, 272, 235–245.
50 Z. Yao, Z. Lai, X. Zhang, F. Peng, H. Yu and H. Wang,
Mater. Res. Bull., 2011, 46, 1938–1941.
45 P. Xiao, M. A. Sk, L. Thia, X. Ge, R. J. Lim, J.-Y. Wang,
K. H. Lim and X. Wang, Energy Environ. Sci., 2014, 7, 2624– 51 Y. Teng, A. Wang, X. Li, J. Xie, Y. Wang and Y. Hu, J. Catal.,
2629. 2009, 266, 369–379.
46 V. M. L. Whiffen, K. J. Smith and S. K. Straus, Appl. Catal., 52 C. Shi, A. M. Zhu, X. F. Yang and C. T. Au, Appl. Catal., A,
A, 2012, 419–420, 111–125.
2004, 276, 223–230.
1232 | Dalton Trans., 2016, 45, 1225–1232
This journal is © The Royal Society of Chemistry 2016