(Fig. 16.4a). Firstly, acid-treated carbon nanotube (CNT) was used as substrate
(Fig. 16.4b1–b2). Afterward, NiO nanoparticles anchored on the surface CNT
composites (NiO-CNTs) were prepared simply via the reflux method followed by
annealing under an argon atmosphere (Fig. 16.4c1–c2). Then, in order to avoid
aggregation during phosphorization and get highly dispersed NiP 2 nanoparticles,
NiO@CNTs were pre-coated with a thin layer of carbon by reacting with
polyvinylidene fluoride (PVDF) (Fig. 16.4d1–d2). It is noted that NiO nanoparticles
can be reduced to Ni after the treatment of PVDF. Besides as a reductive reagent,
PVDF is commonly acted as an excellent fluorinating agent for the synthesis of
inorganic fluorides. Finally, NiP 2 @C-CNTs can be obtained by directly
phosphorizing Ni@C-CNTs by using RP as the phosphorus source at 700
C
(Fig. 16.4e1–e2). The phosphorization process involved in RP needs to be heated
beyond 700
C, which is similar with the previous references [47, 48].
Besides, the strategy of hydrothermal treatment of RP is intensively used to form
TMPs. Yin et al. [44] prepared Sn 4 P 3 /reduced graphene oxide (RGO) hybrids
through an in situ low-temperature solution-based phosphorization chemical transformation route from Sn/RGO (Fig. 16.5a). First, Sn/RGO composites are synthesized by reducing SnCl 2 to Sn with the presence of NaBH 4 . Then, Sn 4 P 3 /RGO can
be prepared via in situ phosphorization chemical reaction method, in which RP and
ethanediamine were employed as phosphorus source and solvent, respectively. TEM
and EDX analyses further confirm the successful conversion of Sn/RGO to Sn 4 P 3 /
GRO (Fig. 16.5b–f). The widespread adoption method involved in other inorganic
phosphorus sources for the preparation of TMPs is a gas–solid reaction way. The
PH 3 gas plays a significant role in formation of TMPs due to its highly active
property. However, it is highly flammable and extremely toxic (the gas content at
lever of ppm can be fatal). To this end, some substituents which can in situ release
PH 3 , such as NH 4 H 2 PO 2 , (NH 4 ) 2 HPO 2 , and NaH 2 PO 2 , are widely investigated. To
generate PH 3 , these hypophosphites need to be heated beyond 200
C.
The releasing PH 3 gas can easily react with metal oxide, metal hydroxide, and
metal–organic frameworks to form TMPs. Taking NaH 2 PO 2 , for instance, according
to the below reaction Eq. (16.1), NaH 2 PO 2 can decompose into two substances.
2NaH 2 PO 2 ! Na 2 HPO 4 þ PH 3
ð16:1Þ
The gas–solid reaction strategy is a surfactant-free method and can remain the
morphology of metal precursor to the utmost extent. Furthermore, PH 3 can not only
achieve the transformation from metal precursor to metal phosphide but also reduce
the metal ions. Lou et al. [49] prepared Ni–Co mixed metal phosphides and
amorphous composite nanoboxes (NiCoP/C) through a metal–organic framework
(MOF)-based strategy (Fig. 16.6a). Phase-pure ZIF-67 nanocubes are selected as the
initial reactant. After reacting with a mount of Ni(NO 3 ) 2 at room temperature, the
solid ZIF-67 nanocubes are converted into ZIF-67@LDH nanoboxes (Fig. 16.6b–d).
Afterward, the NiCoP/C nanoboxes are obtained through a simple one-step
phosphidation process (Fig. 16.6e–g). This process is achieved by thermal treating
16.2 Preparation Methods
381
(Fig. 16.4b1–b2). Afterward, NiO nanoparticles anchored on the surface CNT
composites (NiO-CNTs) were prepared simply via the reflux method followed by
annealing under an argon atmosphere (Fig. 16.4c1–c2). Then, in order to avoid
aggregation during phosphorization and get highly dispersed NiP 2 nanoparticles,
NiO@CNTs were pre-coated with a thin layer of carbon by reacting with
polyvinylidene fluoride (PVDF) (Fig. 16.4d1–d2). It is noted that NiO nanoparticles
can be reduced to Ni after the treatment of PVDF. Besides as a reductive reagent,
PVDF is commonly acted as an excellent fluorinating agent for the synthesis of
inorganic fluorides. Finally, NiP 2 @C-CNTs can be obtained by directly
phosphorizing Ni@C-CNTs by using RP as the phosphorus source at 700
C
(Fig. 16.4e1–e2). The phosphorization process involved in RP needs to be heated
beyond 700
C, which is similar with the previous references [47, 48].
Besides, the strategy of hydrothermal treatment of RP is intensively used to form
TMPs. Yin et al. [44] prepared Sn 4 P 3 /reduced graphene oxide (RGO) hybrids
through an in situ low-temperature solution-based phosphorization chemical transformation route from Sn/RGO (Fig. 16.5a). First, Sn/RGO composites are synthesized by reducing SnCl 2 to Sn with the presence of NaBH 4 . Then, Sn 4 P 3 /RGO can
be prepared via in situ phosphorization chemical reaction method, in which RP and
ethanediamine were employed as phosphorus source and solvent, respectively. TEM
and EDX analyses further confirm the successful conversion of Sn/RGO to Sn 4 P 3 /
GRO (Fig. 16.5b–f). The widespread adoption method involved in other inorganic
phosphorus sources for the preparation of TMPs is a gas–solid reaction way. The
PH 3 gas plays a significant role in formation of TMPs due to its highly active
property. However, it is highly flammable and extremely toxic (the gas content at
lever of ppm can be fatal). To this end, some substituents which can in situ release
PH 3 , such as NH 4 H 2 PO 2 , (NH 4 ) 2 HPO 2 , and NaH 2 PO 2 , are widely investigated. To
generate PH 3 , these hypophosphites need to be heated beyond 200
C.
The releasing PH 3 gas can easily react with metal oxide, metal hydroxide, and
metal–organic frameworks to form TMPs. Taking NaH 2 PO 2 , for instance, according
to the below reaction Eq. (16.1), NaH 2 PO 2 can decompose into two substances.
2NaH 2 PO 2 ! Na 2 HPO 4 þ PH 3
ð16:1Þ
The gas–solid reaction strategy is a surfactant-free method and can remain the
morphology of metal precursor to the utmost extent. Furthermore, PH 3 can not only
achieve the transformation from metal precursor to metal phosphide but also reduce
the metal ions. Lou et al. [49] prepared Ni–Co mixed metal phosphides and
amorphous composite nanoboxes (NiCoP/C) through a metal–organic framework
(MOF)-based strategy (Fig. 16.6a). Phase-pure ZIF-67 nanocubes are selected as the
initial reactant. After reacting with a mount of Ni(NO 3 ) 2 at room temperature, the
solid ZIF-67 nanocubes are converted into ZIF-67@LDH nanoboxes (Fig. 16.6b–d).
Afterward, the NiCoP/C nanoboxes are obtained through a simple one-step
phosphidation process (Fig. 16.6e–g). This process is achieved by thermal treating
16.2 Preparation Methods
381