Production and Photoelectric Activity of P and Al Co-Doped ZnO Nanomaterials

Article abstract of DOI:10.1002/ejic.201500246

Materials that have both conductivity and photocatalytic activity are widely applied in electrical devices and as environmental pollution handles. Based on such requirements, phosphorus and aluminium co-doped conductive zinc oxide nanocrystals (PAZO NCs) with novel visible-light catalytic activities have been mass produced by the combustion method. The PAZO NCs have diameters of 30-100 nm and BET specific surface areas of 15.27-18.99 m² g^-1. These PAZO NCs exhibited novel photocatalytic activity and good conductivity [the powder conductivity was (0.98-1.76) ×10^-4 S cm^-1], the reason being mainly attributed to the increase in carrier concentration and defects through P and Al co-doping. In addition, we found that the 3PAZO NCs, in which the molar ratio of Zn to P atoms is 100:3, had the best visible-light catalytic efficiency of the PAZO NCs, and the size of PAZO NCs decreased with increasing doping of phosphorus and aluminium. This study is useful as a reference for the mass production of modified ZnO NCs and its applications, such as in environmental management, photocatalysis, and anti-static electricity.

Full text of DOI:10.1002/ejic.201500246

FULL PAPER
DOI:10.1002/ejic.201500246
Production and Photoelectric Activity of P and Al
Co-Doped ZnO Nanomaterials
[a]
[a]
[a]
[b]
Ya-Juan Deng, Yi Lu, Jin-Ku Liu,* and Xiao-Hong Yang
Keywords: Nanostructures / Conducting materials / Photocatalysis / Doping / Zinc oxide
10–4 Scm ], the reason being mainly attributed to the
–1
Materials that have both conductivity and photocatalytic
activity are widely applied in electrical devices and as
increase in carrier concentration and defects through P and
environmental pollution handles. Based on such require- Al co-doping. In addition, we found that the 3PAZO NCs, in
ments, phosphorus and aluminium co-doped conductive zinc which the molar ratio of Zn to P atoms is 100:3, had the best
oxide nanocrystals (PAZO NCs) with novel visible-light cata- visible-light catalytic efficiency of the PAZO NCs, and the
lytic activities have been mass produced by the combustion
method. The PAZO NCs have diameters of 30–100 nm and
BET specific surface areas of 15.27–18.99m g . These PAZO
NCs exhibited novel photocatalytic activity and good
conductivity [the powder conductivity was (0.98–1.76)ϫ
size of PAZO NCs decreased with increasing doping of
phosphorus and aluminium. This study is useful as a refer-
ence for the mass production of modified ZnO NCs and its
applications, such as in environmental management, photo-
catalysis, and anti-static electricity.
2
–1
the hydrothermal process.[20] However, there are few reports
on P-Al co-doped ZnO (PAZO) NCs. In this work, PAZO
powders showing electrical conductivity and photocatalytic
activity were synthesized by a simple combustion method.
Monoammonium phosphate (NH H PO ) was used as the
phosphorus source for doping and glycine was added at the
same time to support combustion, make fluffy, and reduce
the grain size of the product. Thus, this is an easy and effec-
tive way to obtain a large quantity of product with both
conductive and photocatalytic properties. There are two as-
Introduction
Transparent conducting oxide nanomaterials have been
widely used as transparent electrodes in various fields such
[
1]
[2]
as solar cells, optoelectronic devices, flat panel displays,
4
2
4
[
3]
[4,5]
heat mirrors, and gas sensors
owing to their high elec-
trical conductivity and high optical transmittance in visible
and high-infrared reflectance.[
6–10]
Doped zinc oxide (ZnO)
is a well-known material with a promising transparency,
photocatalysis, and conductivity.[
11,12]
The doping of ZnO
with phosphorus is quite attractive because there are more
pects to the mechanism of P-Al co-doping. The first is the
5
+
2+
valence electrons in P than in Zn , thus each P atom can
contribute more than one electron to the electrical conduc-
[21,22]
replacement of zinc sites by Al atoms (AlZn).
The sec-
ond is anti-site substitutional P and two zinc vacancies
PZn+2VZn configuration) and substitutional P at oxygen
[
13]
tivity.
In addition, doping with the metallic element Al
(
can improve both the conductivity and photocatalytic ac-
tivity of ZnO by extending its absorption range into the
visible-light region,
[23]
sites (PO).
have been attributed to the AlZn and PZn+2VZn configura-
The conductivity and photocatalyst activity
[
14,15]
achieving the macroscopic prepa-
[14,24–26]
tion, whereas the resistance is induced by PO.
On
ration of conductive and photocatalytic materials. The ex-
pected electrical and optical properties can be achieved only
when the dopants occupy the lattice sites of the ZnO ma-
the other hand, pure ZnO NCs have such a wide optical
band gap that they barely absorb energy in the visible-light
[27,28]
region.
The doping of phosphorus and aluminium into
[
16–18]
trix.
There are many reports in the literature on Al- and P-
ZnO NCs can ameliorate this disadvantage such that the
modified ZnO NCs show enhanced photocatalytic activity
under visible light as well as electrical conductivity.
[
19,20]
[19]
doped ZnO.
For example, Wang and co-workers
synthesized Al-doped ZnO powders by the co-precipitation
method and P-doped ZnO nanorods have been prepared by
Results and Discussion
[
[
a] Key Laboratory for Advanced Materials, East China University
of Science and Technology,
Characterizations of PAZO NCs
Shanghai 200237, P. R. China
E-mail: jkliu@ecust.edu.cn
http://hyxy.ecust.edu.cn/
The TEM images of PAZO samples with different doped
content of phosphorus are shown in Figure 1. The low-
magnification images of the 0PAZO, 1PAZO, 3PAZO,
5PAZO, and 10PAZO products are irregular nanoparticles
b] Department of Chemistry, Chizhou University,
Chizhou 247000, P. R. China
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201500246.
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and the grain diameters of the samples decrease from 100
to 30 nm with enhanced doping content of phosphorus. The
selected area electric diffraction (SAED) patterns of the
PAZO samples (see the insets of each image) change with
nanoparticle size; the SAED pattern of 0PAZO shows dif-
fraction spots of a single crystal, whereas the SAED pattern
of 10PAZO shows polycrystal diffraction rings. A small
particle size, corresponding to a large specific surface area,
produces better performances in photocatalysis.[
29,30]
Figure 2. STEM image of 3PAZO (a) and the corresponding ele-
ment mapping images of (b) C, (c) Al, (d) Zn, (e) P, and (f) O and
Figure 1. TEM images of PAZO NCs: (a) 0PAZO, (b) 1PAZO,
(
g) overlaying element mapping images of 3PAZO.
(c) 3PAZO, (d) 5PAZO, and (e) 10PAZO (insets: SAED patterns).
The scanning transition electron microscopy (STEM) im-
age of 3PAZO and corresponding element mapping images Zn, O, Al, P, and C, respectively. As shown in Figure 3 (b),
are illustrated in Figure 2 and show that the elements C, Al, the high resolution spectra of Zn 2p at 1042.73 and
Zn, P, and O are distributed throughout the sample (Fig- 1019.62 eV have been assigned to Zn2p
and Zn2p3/2,
1/2
[
11]
ure 2, a–g). As shown in Figure 2 (d, f), the Zn signal and respectively.
The binding energy of metallic Zn at
[
31]
main O signal overlay each other. In other words, the ZnO 1021.3 eV is not observed, which indicates that Zn exists
is dispersed in a solid solution. Very importantly, the Al in the oxidized state, which is in good agreement with the
and P signals also overlay the main Zn and O signals. XRD analysis (see Figure S2 in Supporting Information).
Therefore, we believe that the ZnO dispersed in the solid The O 1s spectra can be split into two sub-peaks at 530.58
solution is doped with aluminium and phosphorus ele- and 528.87 eV by Gaussian fitting (Figure 3, c), which indi-
ments. We observe that the C signal is a little inconsistent cates that there are two different oxygen states in the
compared with the signals of the other elements. The signal 3PAZO NCs. The shoulder peak at 528.87 eV is related to
2–
at the edge is stronger than the measured area of our prod-
uct, which is placed on a copper grid with a carbon film amid the ZnO wurtzite structure. The 530.58 eV peak is
and the atmospheric carbon influences this result. related to phosphorus doping leading to substitutional oxy-
O
ions surrounded by Zn (or substitutional Al) atoms
[
32]
XPS studies were performed to investigate the chemical gen sites within the ZnO matrix. The Al 2p peak is located
states of P, Al, and C and the surface composition of the at 73.8 eV with lower symmetry than that reported in the
3
PAZO NCs. The X-ray photoelectron spectra (XPS) also literature[33] (Figure 3, d) and the metallic Al binding en-
show that the C, Al, Zn, P, and O elements exist in the ergy at 72.7 eV is not observed. The binding energy peak at
product. Figure 3 (b–f) present the binding energy peaks of 73.8 eV extends to 75.6 eV (Al O ) and 72.7 eV (elemental
2
3
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Al), the presence of which is attributed to nonstoichiomet-
[
19,34]
ric AlO (x Ͻ 1.5).
Therefore the Al–O bond can be
(1)
(2)
x
considered as substitutional Al doping in the ZnO NCs,
even though an atomic percentage of Al was not detected
by XPS. However, the atomic percentage of phosphorus is
about 0.96. The binding energy peaks of metal and oxygen
bonded to phosphorus appear at around 130 and 135 eV,
respectively, so the peak at 132.34 eV is not just ascribed to
P atoms replacing O sites and P–Zn bonds (denoted as PO),
In Equations (1) and (2), Al* and P* represent the chemi-
cal states of Al and P before the formation of the solid
solution. According to Equations (1) and (2), the as-synthe-
sized PAZO NCs have more free electrons and so the carrier
concentration rises, leading to a decrease in electrical resis-
tivity. Additionally, there are more defects due to zinc
vacancies, which enhance the photocatalytic activity. Thus,
a PAZO powder with both conductive capacity and photo-
catalytic ability can be mass produced.
but P atoms substituted in Zn sites to establish P–O bonds
and two zinc atom vacancies (denoted PZn-2VZn).[
35,36]
Ad-
ditionally, Al–O and P–O bonds are evident in the FTIR
spectra (see Figure S2 in Supporting Information). In con-
clusion, the P and Al co-dope in the crystal lattice of ZnO.
The increases in electron and hole concentrations intro-
duced by Al and P[
37]
contribute to the conductivity and
photocatalytic activity of the PAZO powders. The electrons
derived from substitutional Al and interstitial Zn will trans-
fer to the conduction band by optical excitation. The C 1s
peaks at 283.88 and 283.35 eV are close to the C 1s peak at
High Photoelectric Activity
Optical Properties
2
84.60 eV and have been attributed to contaminated car-
[
38]
The UV/Vis absorption spectra are shown in Figure 4a;
compared with the absorption edge of pure ZnO NCs at
bon. Or the carbon is ascribed to a few carbon dots de-
posited on the surface of PAZO NCs, which is testified by
the results of our previous work. Furthermore, it can en-
hance the photocatalytic efficiency even though also influ-
encing the purity of the product.
380 nm, all the PAZO NCs have an extended absorption
edge up to 700 nm, covering almost the whole visible region
of the solar spectrum, which means that a more efficient
absorption overlap with the solar spectrum is generated af-
ter the incorporation of doped P and Al elements. From
the transmittance data, the band gap energies of the PAZO
samples were calculated by a linear fitting process. The
band gap energies were estimated from the intersection of
2
the tangent line with the x axis and a plot of (αhυ) against
the photon energy hυ [eV] shown in Figure 4 (b). It is
known that the optical band gap is directly related to the
carrier concentration. As the phosphorus dosage increases,
the optical band gap becomes narrower probably due to a
reduction of N2 (carrier density).
/3
[39–41]
This reasoning can
also be applied to the variation of the electrical conductiv-
ity. The shrinkage of the optical band gaps of the different
PAZO samples can be expressed by Equation (3)[
42]
in
which ΔEg is the change in the band gap of doped ZnO
compared with undoped ZnO, h is Planck’s constant, m is
the electron effective mass in the conduction band, and ne
is the electron carrier concentration. As can be seen from
Equation (3), the band gap is directly proportional to car-
rier density. It is clear that the PAZO NCs have a smaller
Figure 3. XPS spectra of 3PAZO NCs: (a) All elements; (b) Zn 2p,
(c) O 1s, (d) Al 2p, (e) P 2p, and (f) C 1s.
The combined XPS and STEM results demonstrate that
the PAZO NCs form a substitutional solid solution accord-
ing to the process outlined in Equations (1) and (2).
Figure 4. (a) UV/Vis spectra and (b) Kubelka–Munk plots of
PAZO NCs: a. 0PAZO, b. 1PAZO, c. 3PAZO, d. 5PAZO, and
e. 10PAZO.
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energy gap (Eg) than pure ZnO NCs, for which Eg = density will reduce as the doping P content increases, based
[
11]
3.37 eV.
on the previous analysis in Figure 4. Thus, the smallest res-
istivity was found when the molar ratio of zinc to phos-
phorus atoms was 100:3. The values of conductivity derived
3) from the resistivity are shown in Table 1, and the values
meet the requirement for a conductive filler material.[
In terms of practical applications, it can be used to produce
a film with both conductive and photocatalytic properties
to make the most of solar light. By contrast, Wu et al. de-
veloped a solid-state synthesis to prepare Al O -doped ZnO
(
47,48]
The photoluminescence spectra of the PAZO NCs re-
corded at an excitation wavelength of 290 nm at room tem-
perature are presented in Figure 5. PL spectra have been
used to judge the efficiency of charge carrier trapping, mi-
gration, and transfer, and to measure the survival lifetime
of electron–hole pairs of semiconductors.[ The intensity
of the photoluminescence varies with phosphorus concen-
2
3
semiconductive powders, and the resistivity of ZnO reached
43]
7
[49]
up to 10 Ωcm for ZnO with no doping with Al O .
2
3
tration and the strong UV emission band at about 395 nm
Table 1. Conductive properties of PAZO NCs.
PAZO 1PAZO 3PAZO 5PAZO 10PAZO
has been ascribed to electron–hole recombination.[
44–46]
As
0
the dosage of P increases, the emission intensities are re-
duced, which suggests that doped P can suppress the recom- Resistivity
bination of photogenerated electron–hole pairs.
1.02
0.805
0.568
0.844
0.806
4
[
10 Ωcm]
Conductivity
0.980
1.24
1.76
1.18
1.24
–
4
–1
[10 Scm ]
Visible Photocatalytic Performance
The photocatalytic performance of the PAZO photocata-
lysts with different doped P contents was evaluated by
studying the decomposition reaction of Rhodamine B
Figure 5. PL spectra of PAZO NCs: a. 0PAZO, b. 1PAZO,
c. 3PAZO, d. 5PAZO, and e. 10PAZO.
(Rh. B; Figure 6). Before exposure to solar light illumina-
tion, the photocatalysts were mixed with Rh. B and stirred
for 30 min in the dark. A decrease in concentration of the
dye solution was found as a result of its adsorption by the
Conductive Properties
The method used to test the conductivities of the samples photocatalysts after reaching an adsorption–desorption
is described in the Supporting Information. By measuring equilibrium in the dark. Thus, we can conclude that the co-
the resistivity of each PAZO powder, conductivity can be doped P and Al enhance the adsorption capacity of ZnO
derived according to Equation (4), in which σ is the con- to a certain extent. However, the self-decomposition poly-
0
0
ductivity, ρ is the resistivity, n is the electron density, τ(E ) merization under solar irradiation of Rh. B led to a loss of
is the relaxation time of electrons situated at the Fermi only 8.8%.
level, m* is the effective mass of electrons, and q is the the PAZO photocatalysts; the 3PAZO NCs present the best
F
[
11,12]
Figure 6 (f) shows the degradation rates of
quantity of electric charge.
activity among all the PAZO NCs. The results indicate that
the appropriate molar ratio of phosphorus to zinc atoms
is 3:100. Additionally, the best photoactivity under solar
4) irradiation belonged to 3PAZO NCs with a degradation of
(
9
5.5% for Rh. B within 5 h, whereas the 0PAZO NCs had
This equation was derived from the conductive theory of
metals, but it can be used to explain the relationship be-
tween conductivity and electron concentration in semicond-
uctive metal oxide powders. According to Equation (5), the
effect of electronic contribution near the Fermi surface
could be disscused further.
a degradation efficiency of only 31.2% and the pure ZnO
photocatalyst decomposed Rh. B incompletely during the
same time (see Figure S5 of Supporting Information). The
degradation rate of the 3PAZO NCs is a remarkable
150.0% greater than that of the 0PAZO NCs. However, fur-
ther addition of NH H PO to give a Zn/P ratio of 100:5
4
2
4
and 100:10 led to a decline in the photocatalytic degrada-
tion efficiency. P may not generate sufficient holes[ in
PAZO NCs with higher contents of doped P, which is detri-
35]
(
5)
The equality of E = E mainly contributes to the above mental to the photoredox reaction and causes a decrease in
F
integral. Namely, the conductivity (σ ) mainly depends on the degradation rate. Conversely, a low content of doped P
0
the electronic contribution near the Fermi surface, which is is also detrimental to photodegradation. On the other hand,
equivalent to the valance band maximum of semi- the PAZO photocatalyst with a comparatively large grain
conductors. That is, the conductivity is directly associated size and randomness has a lower photocatalytic ability be-
with the charge carrier concentration. However, the carrier cause the phosphorus is randomly distributed on the AZO
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surface. However, the extension of the optical adsorption ure 7). It is clear that pure ZnO shows the worst photo-
region counteracts this defect.
stability in the recycling experiments, which has been attrib-
[
51–54]
uted to photocorrosion.
The photocatalytic conver-
sion of pure ZnO decreased to 58.6%, which compares with
the nearly unchanged photocatalytic performance of the
3PAZO photocatalyst after seven recycles. Thus, not only
the photocatalytic activity but also the photostability is im-
proved after co-doping Al and P in ZnO.
Degradation Mechanism of PAZO NCs
The PAZO NCs show enhanced photocatalytic activity
compared with pure ZnO NCs. The mechanism for the de-
gradation of Rh. B by PAZO photocatalysts under solar
light irradiation is discussed below and illustrated in Fig-
ure 8.
Figure 8. Degradation mechanism of PAZO NCs.
Figure 6. UV/Vis curves of Rh. B degradation for different PAZO
NCs: a) 0PAZO, b) 1PAZO, c) 3PAZO, d) 5PAZO, e) 10PAZO, and
f) degradation rates.
The conductive PAZO powders have been proven to
exhibit beneficial photocatalytic performance under solar
light because the range of optical absorption extends to the
visible light region and the recombination of photo-
generated electron–hole pairs is reduced, however, the carri-
ers are partially inhibited when the material is used as a
The BET surface areas of each PAZO photocatalyst are
shown in Figure S3 in the Supporting Information. All the
adsorption–desorption isotherms exhibit a hysteresis loop
typical of the type IV pattern according to the classification
[
14]
[
50]
photocatalyst. A promising way to solve this problem is
to design and fabricate novel catalysts with rapid electron
transfer and visible photoresponse capabilities. Based on
this idea, P-Al co-doped ZnO NCs were matched to im-
prove the properties of the ZnO photocatalyst. The photo-
induced electrons on the surface of the Al atom transfer to
ZnO and holes from P atoms transfer to ZnO, which pro-
motes charge separation and higher photodegradation effi-
ciency. Based on the degradation results of Rh. B, the syn-
ergetic effect between P and Al plays a vital role in the pho-
tocatalysis by the PAZO NCs, even if the doping can de-
crease the photocatalytic activity, which induces defects at
the electron–hole recombination sites in the photocata-
of IUPAC.
The BET surface areas are larger than the
2
–1
pure ZnO NCs (11.52 m g ), and so the photocatalytic
efficiencies are improved by doping with P and Al.
Photostability
The photostability of the 3PAZO NCs in the photo-
degradation of Rh. B under solar light irradiation was
characterized by photocatalytic recycling experiments (Fig-
[
55]
lysts.
More importantly, the PAZO photocatalysts are
constructed by a highly efficient and facile synthesis and
have highly desirable properties.
The photocatalytic degradation of the PAZO NCs is ef-
ficient under solar light irradiation because the band gap
energy of ZnO (3.37 eV) diminishes to 2.86 eV (Figure 4, b)
after doping with P and Al atoms. In addition, the photo-
absorption range is broadened to the visible light region.
When the PAZO photocatalyst receives solar energy, the
electrons on the surface of the photocatalyst will migrate
from the valance band (VB) to the conduction band (CB)
Figure 7. Stability of the photocatalysts in the degradation of Rh. B
under solar light irradiation.
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and leave holes in the VB. O and H O will then react with poured into the agitator until these mixtures change to a viscous
2
2
–
clear liquid, which shows that they are mixed thoroughly. The li-
quid is then placed in an oven and baked at about 180 °C until no
smoke is emitted. The precursor is then calcined at 600 °C for 2 h.
Then the product should be ground to a uniform particle size. In
this way it is easy to achieve mass production for use in the solution
of environment pollution problems.
the electrons and holes, respectively, to produce O · and
HO· , which are highly reactive, degrading Rh. B to CO2
2
–
and H O. Therefore the PAZO NCs display enhanced
photocatalytic activity in comparison with pure ZnO NCs.
2
Conclusions
Several unique aspects of this work are worth high-
lighting. 1) A combustion method that is efficient and
suitable for industry has been explored for the mass pro-
duction of PAZO NCs with good visible light response and
electrical conductivity, and has provided a facile method
for the manufacture of other solid solutions through the
formation of favorable substitutional solid solutions. 2) The
low cost, environmental compatibility, and considerable
photocatalytic effect of PAZO NC powders would be ad-
vantageous in the process of sewage disposal. 3) The PAZO
NCs obtained show enhanced photoelectrical properties.
The powder can make the most of solar energy and be used
in conductive fillers due to its excellent photocatalytic
activity under solar light and good conductivity.
Figure 9. Preparation of PAZO NCs.
Characterization: The structures and morphologies of the PAZO
NCs were investigated by transmission electron microscopy (TEM,
Hitachi-800) at an acceleration voltage of 200 kV. Scanning trans-
mission electron microscopy (STEM) was performed with a JEM-
2100F instrument to show atom distribution on the PAZO NC
surface. The light absorption of the samples was studied by UV/
Vis spectroscopy (Shimadzu, UV-2600). The surface compositions
of the products were investigated by X-ray photoelectron spec-
troscopy (XPS, VG ESCALAB MK II). The fluorescence proper-
ties were studied with a fluorescence spectrophotometer (Cary
Eclipse, Varian).
Experimental Section
Materials: Zinc nitrate hexahydrate [Zn(NO
nitrate nonahydrate [Al(NO ·9H O], monoammonium phosphate
NH PO ), glycine (C NO ). Rhodamine B (Rh. B) were used
3 2 2
) ·6H O], aluminium
3
)
3
2
(
4
H
2
4
2
H
5
2
for the photocatalytic studies. All the reagents were of analytical
grade and used without further purification.
Preparation of PAZO Nanocatalysts: The PAZO nanocatalysts were
synthesized by the combustion method. Zinc nitrate hexahydrate
(
2
2.97 g, 0.01 mol), aluminium nitrate nonahydrate (0.075 g,
.0ϫ10–4 mol), glycine (1.5 g, 0.02 mol), and monoammonium
Photocatalytic Properties: To evaluate the photocatalytic activities
of the synthesized photocatalysts, Rhodamine B (Rh. B) was
chosen as a model pollutant and its photodegradation was studied
over all the samples. Sunlight (from 10:00 to 16:00, the highest
temperature was 35 °C) was used as the light source. In a typical
experiment, the photocatalyst (0.08 g) was added to a 50 mL quartz
phosphate in different molar ratios of phosphorus to zinc atoms
was used as the phosphorus source by grinding in an agate mortar.
The resulting mixture was added to a mortar and ground fully to
obtain a transparent liquid, poured into a crucible, and then placed
in a drying oven and heated at about 180 °C. Tt was then calcined
at 600 °C in a muffle furnace for 2 h. Finally, PAZO NCs with
different doping concentrations of phosphorus atoms were ob-
tained.
–
5
batch reactor containing 2ϫ 10 mol/L aqueous solution of Rh. B
50 mL). The reaction system was stirred for 30 min in the dark to
(
allow the adsorption–desorption equilibrium to be reached before
irradiation. Samples were taken hourly to test the absorbance of
the Rh. B solution and its concentration. The UV/Vis absorption
spectra of samples were recorded with time at room temperature
by using a UV-2450 (Shimadzu) spectrometer.
The photocatalysts obtained by using molar ratios of zinc to phos-
phorus atoms of 100:0, 100:1, 100:3, 100:5, and 100:10 were desig-
nated as 0PAZO, 1PAZO, 3PAZO, 5PAZO, and 10PAZO, respec-
tively.
The photodegradation rate (PDT) is defined by Equation (9), in
which C is the initial concentration of Rh. B and C is the concen-
0 t
tration of Rh. B after photodegrading for t hours. In this way, the
The reactions involved in the heating process to give P-Al co-doped
PAZO NCs are shown in reactions 6, 7 and 8.
activities of the different photocatalysts were quickly qualified.
3 2 2 2 5 2 2 2 2
Zn(NO ) ·6H O + C H NO ǞZnO + NO Ȇ + H OȆ CO Ȇ
(
6)
Al(NO
3
)
2
·9H
2
O + C
2
H
5
NO
2
ǞAl
2
O
3
+ NO
2
Ȇ + H
2
OȆ CO
2
Ȇ
(9)
(
7)
Acknowledgments
Zn(NO
3 2 3 2 4 2 4 2 3
) + Al(NO ) + NH H PO ǞPAZO + H OȆ + NH Ȇ
+
NO
2
Ȇ
(8)
This work was supported by the National Natural Science Founda-
tion of China (NSFC) (grant number 21341007), the Fundamental
Research Funds for the Central Universities (grant number
Figure 9 shows a scheme for the industrial preparation of the
PAZO nanocatalysts. Each of the chemical raw materials are
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[
[
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