H. He et al. / Journal of Alloys and Compounds 522 (2012) 63–68
67
Fig. 8. Schematic diagram of the Zn nanoparticles loaded on TiO2NTs and the electrons transfer and separation between the contact interfaces of Zn nanoparticles and
TiO2NTs.
implied the resistance of Zn/TiO2NTs was affected by the distribu-
tion and particles size of Zn nanoparticles. The Zn/TiO2NTs prepared
at ton = 11 ms owned the smallest semicircle radius of Nyquist plots
which meant the fastest electrons transferring properties.
Zn nanoparticles on the photoelectrochemical properties of
Zn/TiO2NTs were investigated. The results showed that the size
and distribution effect of Zn nanoparticles played a crucial role
in the transfer and separation of carriers. The optimal photoelec-
trochemical properties was registered in the case of Zn/TiO2NTs
prepared at ton = 11 ms due to the moderate size (40–50 nm)
and distribution Zn nanoparticles loaded on/into TiO2NTs
forming abundant contact interfaces between Zn nanoparticles
and TiO2NTs which can transfer and separate carriers effectively.
The present work provide reference and insights for designing
and preparing highly photoelectrochemical activity metal/TiO2NTs
nanocomposites.
caused the discrepancies in photoelectrochemical properties on
Zn/TiO2NTs. These discrepancies are related to the separation and
can isolate and transfer electrons from the TiO2NTs through the
cles and TiO2NTs (shown in Fig. 8). The appropriately dispersed Zn
separation and transmission of carriers (Fig. 8; ton = 11 ms). On the
TiO2NTs were formed when big (Fig. 8; ton = 8 ms) or agglomer-
ated (Fig. 8; ton = 14 ms) Zn nanoparticles loaded on TiO2NTs, which
intrinsically lead to high recombination probability of electrons
and holes and discontinuous electrons transfer [24]. In addition,
it has been reported that the work function of metal was influ-
enced by the particle size. If the size of metal particles was too
large, its energetic properties may approach to that of bulk. The
work function of metals would be decreased, and then electron
could not be transferred effectively [25]. Compared with the sample
B (ton = 11 ms), the Zn particles of sample A (ton = 8 ms) had bigger
size and distribution and were only deposited on the top of TiO2NTs,
thus the carriers separation and transmission were decreased. The
smaller Zn nanoparticles of sample C (ton = 14 ms) were easy to
agglomerate, which resulted in less contact interfaces between Zn
nanoparticles and TiO2NTs and the increase of transmission resis-
tance of the carriers. Moreover, the work function of agglomerated
Zn nanoparticles was similar to that of bulk, which also had impact
on the transferred efficiency of carriers. Hence, the optimal pho-
toelectrochemical properties of Zn/TiO2NTs was presented when
Zn nanoparticles were appropriately dispersed on/into TiO2NTs
(ton = 11 ms).
Acknowledgment
This work was supported by the Fundamental Research Funds
for the Central Universities (Project No. CDJXS11221174).
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In this paper, Zn nanoparticles with different size and dis-
tribution were loaded on/into TiO2 nanotube arrays by pulsed
electrodeposition method. The influences of morphology of