demonstrates the catalyst has hopeful prospects in the field of splitting seawater
(Fig. 16.13g).
Zhang et al. [74] reported for the first time on preparation of CoP/TiO 2 hybrid for
application in photocatalytic hydrogen evolution reaction. The apparent quantum
efficiency (AQE) for 0.5 wt% CoP/TiO 2 at 350 nm is calculated to be 3.8% in 10 vol
% triethanolamine solution under simulated solar light irradiation (Fig. 16.14a). It is
noted that the CoP/TiO 2 composite catalyst showed the highly stable activity in
long-standing photocatalytic experiment (Fig. 16.14b). From the Mott–Schottky
analysis (Fig. 16.14c–d), it is noted that the flat band potentials for TiO 2 and CoP
are À0.51 and À0.12 V versus Ag/AgCl, respectively, which reveals the injection of
photo-generated electrons from TiO 2 into conductive band of CoP that is allowed in
the energetic level. Different from the other TMPs photocatalytic systems, both TiO 2
and CoP in this system can be easily excited to form charges under solar light
irradiation, and the electrons from the CB of TiO 2 can easily transfer to the CB of
CoP. Meanwhile, holes from the VB of TiO 2 can inject into the VB of CoP.
Therefore, the two kinds of photo-generated charge carriers are accumulated on
CoP, and then they, respectively, go through two processes. Taking the CB electrons
on CoP for instance, on the one hand, these electrons are used for participating H 2
evolution reaction; on the other hand, they combine with holes to accelerate chargecarrier recombination (Fig. 16.14e).
Except as the cocatalyst, cobalt phosphide also can be used as photocatalytic
semiconductor to be application in photocatalytic water splitting. Sun et al. [75] used
CoP nanowires to achieve highly photocatalytic hydrogen evolution with the presence of the probe of human immunodeficiency virus (P HIV ) through dye-sensitized
process. An obvious enhancement on activity with the addition of P HIV can be
observed. An energy level diagram illustrates that under light irradiation, the electron
from P HIV can inject into the CB of CoP, and TEOA can react with the holes, thus
improving the amount of electrons and charge separation efficiency.
16.4.3.3 Other TMPs As Cocatalyst
Except for these two commonly used cocatalysts (Ni 2 P and CoP), other TMPs such
as Cu 3 P [76], FeP [77], and MoP [32] have been intensively used to drive the
photocatalytic water reduction.
Du and his coworkers [78] prepared MoP-modified CdS nanorods through a
mechanical commixture method. In order to understand the formation of MoP/CdS,
the DFT calculations are used to calculate the surface energy of MoP (001), (100),
and (101) surfaces (Fig. 16.15a). The Mo-terminated surfaces have higher surface
energy than P-terminated surfaces. Furthermore, the MoP (100) surface has the
largest surface energy of 0.509 and 0.242 eV Å
À2 for Mo- and P-terminated surfaces,
which suggests the high energy surface is unstable and easily disappears. However,
after introducing CdS, the surface with high surface energy can be remained by the
intimate attachment of MoP and CdS. In the first cycle, the apparent quantum yields
(AQYs) gradually increase with the increment of irradiation time (Fig. 16.15b). It is
394
16 Transition Metal Phosphide As Cocatalysts for Semiconductor-Based. . .
(Fig. 16.13g).
Zhang et al. [74] reported for the first time on preparation of CoP/TiO 2 hybrid for
application in photocatalytic hydrogen evolution reaction. The apparent quantum
efficiency (AQE) for 0.5 wt% CoP/TiO 2 at 350 nm is calculated to be 3.8% in 10 vol
% triethanolamine solution under simulated solar light irradiation (Fig. 16.14a). It is
noted that the CoP/TiO 2 composite catalyst showed the highly stable activity in
long-standing photocatalytic experiment (Fig. 16.14b). From the Mott–Schottky
analysis (Fig. 16.14c–d), it is noted that the flat band potentials for TiO 2 and CoP
are À0.51 and À0.12 V versus Ag/AgCl, respectively, which reveals the injection of
photo-generated electrons from TiO 2 into conductive band of CoP that is allowed in
the energetic level. Different from the other TMPs photocatalytic systems, both TiO 2
and CoP in this system can be easily excited to form charges under solar light
irradiation, and the electrons from the CB of TiO 2 can easily transfer to the CB of
CoP. Meanwhile, holes from the VB of TiO 2 can inject into the VB of CoP.
Therefore, the two kinds of photo-generated charge carriers are accumulated on
CoP, and then they, respectively, go through two processes. Taking the CB electrons
on CoP for instance, on the one hand, these electrons are used for participating H 2
evolution reaction; on the other hand, they combine with holes to accelerate chargecarrier recombination (Fig. 16.14e).
Except as the cocatalyst, cobalt phosphide also can be used as photocatalytic
semiconductor to be application in photocatalytic water splitting. Sun et al. [75] used
CoP nanowires to achieve highly photocatalytic hydrogen evolution with the presence of the probe of human immunodeficiency virus (P HIV ) through dye-sensitized
process. An obvious enhancement on activity with the addition of P HIV can be
observed. An energy level diagram illustrates that under light irradiation, the electron
from P HIV can inject into the CB of CoP, and TEOA can react with the holes, thus
improving the amount of electrons and charge separation efficiency.
16.4.3.3 Other TMPs As Cocatalyst
Except for these two commonly used cocatalysts (Ni 2 P and CoP), other TMPs such
as Cu 3 P [76], FeP [77], and MoP [32] have been intensively used to drive the
photocatalytic water reduction.
Du and his coworkers [78] prepared MoP-modified CdS nanorods through a
mechanical commixture method. In order to understand the formation of MoP/CdS,
the DFT calculations are used to calculate the surface energy of MoP (001), (100),
and (101) surfaces (Fig. 16.15a). The Mo-terminated surfaces have higher surface
energy than P-terminated surfaces. Furthermore, the MoP (100) surface has the
largest surface energy of 0.509 and 0.242 eV Å
À2 for Mo- and P-terminated surfaces,
which suggests the high energy surface is unstable and easily disappears. However,
after introducing CdS, the surface with high surface energy can be remained by the
intimate attachment of MoP and CdS. In the first cycle, the apparent quantum yields
(AQYs) gradually increase with the increment of irradiation time (Fig. 16.15b). It is
394
16 Transition Metal Phosphide As Cocatalysts for Semiconductor-Based. . .