Facile synthesis of Ag3VO4/β-AgVO3 nanowires with efficient visible-light photocatalytic activity

Article abstract of DOI:10.1039/c7ra03955g

Ag₃VO₄/β-AgVO₃ nanocomposites were successfully fabricated by chemical precipitation and hydrothermal method. The composites displayed excellent photocatalytic activity in comparision with those of pure β-AgVO₃ and Ag₃VO₄, which may be primarily ascribed to the matched energy structures. The sample with a molar ratio of 30% Ag₃VO₄ to β-AgVO₃ showed the highest photocatalytic activity for RhB degradation, which was almost 9 and 2.4 times higher than those of pure β-AgVO₃ and Ag₃VO₄, respectively. In addition, the trapping experiments also confirmed that holes and hydroxyl radicals are the active species for RhB degradation, and the possible mechanism for enhanced photocatalytic activity was proposed.

Full text of DOI:10.1039/c7ra03955g

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Facile synthesis of Ag VO /b-AgVO nanowires
3
4
3
with efficient visible-light photocatalytic activity
Cite this: RSC Adv., 2017, 7, 27515
ab
Lei Gao, Zhonghua Li *b and Jiawen Liu*c
Ag
hydrothermal method. The composites displayed excellent photocatalytic activity in comparision with
those of pure b-AgVO and Ag VO , which may be primarily ascribed to the matched energy structures.
The sample with a molar ratio of 30% Ag VO to b-AgVO showed the highest photocatalytic activity for
RhB degradation, which was almost 9 and 2.4 times higher than those of pure b-AgVO and Ag VO
3
VO
4
/b-AgVO
3
nanocomposites were successfully fabricated by chemical precipitation and
3
3
4
3
4
3
Received 7th April 2017
Accepted 15th May 2017
3
3
4
,
respectively. In addition, the trapping experiments also confirmed that holes and hydroxyl radicals are
the active species for RhB degradation, and the possible mechanism for enhanced photocatalytic activity
was proposed.
DOI: 10.1039/c7ra03955g
rsc.li/rsc-advances
32
Ag
enhance the separation of photoinduced charge carriers.
AgVO with excellent optical absorption in the visible light
tion from researchers because it is one of the most green and region has also attracted considerable attention due to its
3
PO
4
(ref. 31) and Ag
3
VO
4
/g-C
3
N
4
,
have been developed to
1
Introduction
Heterogenerous photocatalysis has gained widespread atten-
3
3
3–35
effective methods to solve the energy shortage and environ- narrow band gap, high stability and well crystallization.
1–3
mental problems. Over the past several decades, more and However, compared with other Ag-based materials such as
3
6
37
38
more photocatalysts have been developed, including TiO
2
, ZnO, Ag
3
PO
4
,
AgX, and Ag
2
CO
3
,
there are only few studies
4
–10
Ta O and CuO.
However, most of them had a high rate of concentrated on degradation of pollutants about AgVO
3
, which
2
5
charge carrier recombination and no response in the visible may be attributed to low quantum yield and the poor absorption
light range. It is very important to effectively utilize solar energy efficiency in visible light. Therefore, a suitable material coupled
to overcome the above two limitations. Heterostructured pho- with AgVO
tocatalysts,
is of great importance to solve its limited applica-
an effective media, have been developed to avoid tion in photocatalysis.
the recombination of photoinduced electron–hole and increase
In this study, we reported novel Ag
the charge carrier separation efficiency because of the interface through a chemical precipitation approach. We chose one-
electric eld. Hence, many different composites have been dimensional b-AgVO nanowires as the substrate materials
prepared and reported, such as Ag/AgX, Ag/AgX/GO, RGO/ because they have lots of advantages such as visible light
3
11–16
VO /b-AgVO composites
3 4 3
3
17
18
1
9,20
21
Bi3.64M0.36O6.55
,
2
AgX/Ag PO , InVO /BiVO (ref. 22–26) and responding and supporting materials. A facile chemical
3 4 4 4
7
BiPO /Ag PO .
precipitation can efficiently suppress the aggregation of Ag
with a band energy of and boost the contact between Ag VO and b-AgVO . The
.3 eV has received much attention due to its good photo- Ag VO /b-AgVO hybrid materials were used for the photo-
catalytic activity under visible light irradiation. Although the degradation of RhB under visible light and exhibited much
pure Ag VO
exhibits high photocatalytic performance, its higher photocatalytic activity than single Ag VO and b-AgVO
photocatalytic activity is limited because of its low efficiency in Moreover, a possible photocatalytic mechanism and the
3 4
VO
4
3
4
The monoclinic scheelite Ag
3
VO
4
3
4
3
2
3
4
3
3
4
3
.
3
4
3 4 3
separating photogenerated electrons and holes. Hence, many stability of the Ag VO /b-AgVO heterojunction were also
Ag VO -based heterostructure photocatalysts such as Ag VO / investigated.
3
4
3
4
28
29
30
TiO2, Ag O/Ag VO /Ag V O , Ag O/Ag VO /AgVO , Ag VO /
2
3
4
4
2
7
2
3
4
3
3
4
2
Experimental
a
School of Chemistry and Chemical Engineering, Harbin Institute of Technology,
2
.1 Preparation of b-AgVO nanowires
Harbin 150001, P. R. China
3
b
Key Laboratory of Microsystems and Microstructures Manufacturing, Ministry of
All reagents for synthesis and analysis were analytical grade and
Education, Harbin Institute of Technology, Harbin 150001, P. R. China. E-mail:
lizh@hit.edu.cn
used without further purication. b-AgVO3 nanowires were
39
synthesized by the previously reported hydrothermal method.
mmol NH VO (Tianjin bo di reagent co., LTD, Certied
c
Key Laboratory for Photochemical Biomaterials and Energy Storage Materials, College
1
4
3
of Chemistry and Chemical Engineering, Harbin Normal University, Harbin 150025,
Heilongjiang Province, P. R. China. E-mail: jiawen86@163.com
China) was dissolved in 60 mL deionized water (Harbin zhong
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ꢁ
1
jia chemical reagent co., LTD, Certied China) with magnetic (10 mg L ) in a quartz reactor. Prior to the light illumination,
stirring for 5 min to obtain a transparent solution under room the suspension was stirred in the dark for 30 min to achieve the
temperature. Then, 1 mmol AgNO (Shanghai shi yi chemical adsorption–desorption equilibrium on the surface of photo-
3
reagent co., LTD, Certied China) was slowly added into the catalyst. At dened time (10 min), about 3 mL of the reaction
above solution and stirred for another 3 min. The pH value of solution was withdrawn and centrifuged (11 000 rpm, 1 min) to
the solution was adjusted to 8–8.2 by using NH $H O (25–28%) remove the photocatalyst particles. The residual amount of RhB
3 2
and then the mixture was homogeneously transferred into ve in the solution was recorded by measuring its characteristic
ꢀ
2
1
0 mL Teon-lined stainless vessel and heated at 180 C for optical absorption at 554 nm using UV-vis spectrophotometer.
2 h. The b-AgVO
3
nanowires were collected by centrifugation,
washed with deionized water three times, dried at 60 C for 10 h.
ꢀ
3
Results and discussion
2
.2 Synthesis of Ag VO /b-AgVO composites
3 4 3
The typical XRD patterns for the pure b-AgVO
Ag VO /b-AgVO composites are shown in Fig. 1. The pure b-
AgVO patterns match well with the JCPDS (29-1154) standard
data, which suggests that the prepared b-AgVO has a mono-
3 3 4
, Ag VO and
Ag VO /b-AgVO composites were prepared by a chemical
precipitation method. 0.1034 g as-prepared b-AgVO nanowires
and 0.1010 g AgNO (Shanghai shi yi chemical reagent co., LTD,
Certied China) dispersed in 40 mL deionized water with
magnetic stirring for 5 min. Subsequently, 20 mL of a certain
3 4 2
amount of Na VO $12H O (Beijing chemical reagent co., LTD,
Certied China) aqueous solution was dropped into the above
solution and stirred for 3 h. The obtained yellow precipitate was
3
4
3
3
4
3
3
3
3
3
40
clinic structure. The diffraction peaks of Ag VO can be
3
4
4
1
indexed as the JCPDS (43-0542) standard data. It was clearly
found that all the Ag VO /b-AgVO composites exhibit a cooc-
currence of both b-AgVO and Ag VO phases. Furthermore,
with the Ag
intensity of Ag
3
4
3
3
3
4
3
VO
4
amounts increasing, the diffraction peak
washed with distilled water three times and dried in oven at
3
VO
4
becomes stronger gradually. Meanwhile, the
ꢀ
60 C for 6 h. Ag VO /b-AgVO composites with different molar
3
4
3
diffraction peak positions of b-AgVO do not shi, indicating
that the introduction of Ag VO does not inuence the crystal
3
ratios of Ag VO were obtained: 5%, 10%, 20%, 30%, 40% and
3
4
3
4
the samples prepared were denoted as 5% Ag
0% Ag VO /b-AgVO , 20% Ag VO /b-AgVO , 30% Ag
AgVO and 40% Ag VO /b-AgVO , respectively.
3
VO
4
/b-AgVO
3
,
structure of b-AgVO3.
Fig. 2(a) shows the UV-vis diffuse reectance spectra of pure
b-AgVO Ag VO and Ag VO /b-AgVO composite photo-
catalysts in order to investigate the optical absorption proper-
ties. As depicted from Fig. 2(a), b-AgVO and Ag VO display
The crystalline structures of the samples were recorded on excellent optical absorption in visible light. Their absorption
1
3
4
3
3
4
3
3
VO /b-
4
3
3
4
3
3
,
3
4
3
4
3
2
3 4 3
.3 Characterization of Ag VO /b-AgVO composites
3
3
4
a Rigaku D/MAX-rA XRD (Japan) with Cu K
a
radiation (l ¼ edges were approximately 640 nm and 615 nm respectively.
ꢀ
n/2
0.15405 nm) in the range of 20–70 (2q). The images of the From the formula: ahn ¼ A(hn ꢁ E ) , where a is the absorption
g
micro-morphology were determined by scanning electron coefficient, hn is the energy, A is a constant, and E is the band
g
microscopy (SEM, Hitachi, SU8010) and Transmission electron gap. The value of n depends on whether the transition is direct
microscope (TEM, Tecnai, G2F30). The surface analysis was (n ¼ 1) or indirect (n ¼ 4) discrete photon in a semiconductor.
studied by X-ray photoelectron spectroscopy (XPS, Thermo As shown in Fig. 2(b), we can get the band gap E of pure b-
g
Fisher Scientic, ESCALAB250Xi) with a Mg Ka source. The AgVO3 and Ag VO to be 2.20 eV and 2.37 eV, respectively.
3
4
binding energies were calibrated with the C 1s peak of surface Moreover, the potential of conduction band of Ag VO and b-
3
4
adventitious carbon at 284.8 eV. The Ultraviolet-visible Diffuse
Reectance Spectra (UV-vis DRS) were obtained in the range of
255–800 nm using a UV-vis spectrophotometer (UV-2550, Shi-
madzu, Japan). BaSO4 was used as the reectance standard
material. The BET surface area was measured by N adsorption
2
using a surface analysis instrument (Beishide, 3H-2000PSI,
China). The photoluminescence spectra (PL) of the catalysts
were recorded using a FluoroMax-4 photoluminescence instru-
ment (HORIBA JobinYvon) with a 350 nm excitation wavelength.
2
.4 Evaluation of photocatalytic performance
The photocatalytic properties of the Ag VO /b-AgVO
samples were evaluated by the degradation of rhodamine B
RhB) dye under visible light irradiation. A 300 W Xe lump was
employed as visible light (l > 400 nm) source and NaNO
solution was poured between the lump and the photocatalyst to
lter out UV light (l < 400 nm). The vertical distance between
the light source and the surface of the solution was about 12 cm.
.0500 g photocatalyst was dispersed into the 70 mL of RhB b-AgVO
3
4
3
composite
(
2

Fig. 1 XRD patterns of b-AgVO
b), 10% Ag VO /b-AgVO (c), 20% Ag
(e), 40% Ag VO /b-AgVO (f) and Ag
3
nanoribbons (a), 5% Ag
VO /b-AgVO
VO
3
VO
4
/b-AgVO
3
(
3
4
3
3
4
3
(d), 30% Ag
4
(g).
3 4
VO /
0
3
3
4
3
3
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Fig. 2 (a) UV-vis diffuse reflectance spectra of b-AgVO
3
, Ag
3
VO
4
and
2
Fig. 3 SEM images of b-AgVO nanoribbons (a), 5% Ag VO /b-AgVO
Ag
3
VO
4
/b-AgVO
3
composites. (b) Plots of (ahn) versus hn of pure b-
3
3
4
3
3
(b), 10% Ag VO
4
/b-AgVO
3
(c), 20% Ag
3
VO
4
/b-AgVO
3
(d), 30% Ag
3
VO
4
/
AgVO
3
, Ag
3
VO and Ag
4
3
VO
4
/b-AgVO
3
composites.
b-AgVO (e) and 40% Ag
3
3
VO
4
/b-AgVO
3
(f).
AgVO could be calculated by the following Mulliken electro-
3
e
circle in Fig. 4(c). By measuring the lattice fringes, the inter-
planar spacing is 0.317 nm and 0.243 nm, which are corre-
negativity theory: ECB ¼ c ꢁ E ꢁ 0.5E
g
, where c is the absolute
e
electronegativity of the semiconductor, E is the energy of free
electrons (4.5 eV), and E is the band gap energy of semi-
conductor. The c values of Ag VO and b-AgVO are 5.64 and
.88, respectively. So the CB values of Ag VO and b-AgVO were
sponding to the (ꢁ301) plane of b-AgVO
Ag VO
XPS analysis was carried out to further clarify the surface
chemical composition and bonding environment of 30%
3
and the (202) plane of
g
3
4
.
3
4
3
5
3
4
3
calculated to be ꢁ0.045 and 0.28 eV, respectively. Based on the
equation E ¼ E + E , the corresponding E values were also
VB
CB
g
VB
predicted to be 2.325 and 2.48 eV, respectively. The results
indicate that the composite could successfully fabricate the
matched energy structures between Ag
The microstructures of pure b-AgVO
AgVO composite photocatalysts were measured by SEM. As
shown in Fig. 3(a), pure b-AgVO displays a number of nano-
3
VO
4
and b-AgVO3.
3
, Ag
3
VO and Ag VO /b-
4
3
4
3
3
wires with about 100 nm in width and more than 20 mm in
length and its surface is very smooth. As depicted in Fig. 3(b)–
(
f), the composites of Ag VO /b-AgVO do not inuence the
3 4 3
shape of b-AgVO
larger with the Ag
3
and the size of Ag
VO content increasing, which is in agree-
ment with the enhanced intensity of Ag VO XRD patterns.
The morphology of 30% Ag VO /b-AgVO composite is
further illustrated by TEM and HRTEM. Fig. 4(a)–(c) show that
some Ag VO nanoparticles appeared on the smooth surface of
3 4
VO particles becomes
3
4
3
4
3
4
3
3
4
42
b-AgVO nanowires. HRTEM in Fig. 4(d) is the location of the Fig. 4 (a)–(c) TEM images of 30% Ag VO /b-AgVO composite and (d)
3
3
4
3
HRTEM images of the designated square area in panel of (c).
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3 4 3
Ag VO /b-AgVO composite and the results are displayed in
Fig. 5. The binding energy at 248.8 eV of C 1s is calibrated. The
Fig. 5(a) and (b) demonstrates the predominant presence of
silver and vanadium. The two peaks at 367.5 and 373.5 eV can
+
be corresponding to the Ag 3d5/2 and Ag 3d3/2 of Ag both in
4
1,43
Ag
AgVO
3/2 of V both in Ag
The photocatalytic performance of pure b-AgVO
and Ag VO /AgVO composites was evaluated by photocatalytic
3
VO
4
and b-AgVO
3
.
3 4
The V 2p peaks of 30% Ag VO /b-
3
at 516.9 and 524.2 eV can be assigned to V 2p5/2 and V
5
+
41,43
2p
3 4 3
VO and b-AgVO .
3
3 4
, Ag VO
3
4
3
degradation of RhB under visible light illumination. Fig. 6
displays the experimental results. It can be seen that aer
6
0 min of visible light irradiation the degradation efficiency of
pure b-AgVO and Ag VO were 23% and 57% respectively.
Obviously, all the composites have more effective photocatalytic Fig. 6 Photocatalytic degradation of RhB over Ag VO /b-AgVO
3
3
3
4
3
4
performance than the pure samples, which can be attributed to nanowire composites under visible light irradiation.
the presence of Ag VO on the surface of b-AgVO , accelerating
3
4
3
the separation of photoinduced electrons and holes. The best
photocatalytic performance comes from 30% Ag VO /b-AgVO
that the excessive Ag VO particles deposited on the surface of
3 4
3
4
3
composite, which is 9 times and 2.4 times than pure b-AgVO3 b-AgVO might intervene the photocatalytic activity sites.
3
and Ag
3
VO
4
. However, with the content of Ag
3
VO
4
enhanced to
Fig. 7 exhibits the obvious changes of RhB solution in UV-
4
0%, the decomposition efficiency of RhB declines, suggesting visible absorption spectra of 30% Ag VO /b-AgVO composite
3
4
3
at different times. It can be clearly observed that the absorbance
maximum peak of RhB shis from 554 nm to 504 nm, which is
in good accordance with the previous reports of the degradation
29
of RhB over TiO (ref. 44) and Ag O/Ag VO /Ag V O . The color
2
2
3
4
4 2 7
of RhB solution changes from pink to almost colourless aer
0 min illumination, which indicates the cleavage of conjugated
6
chromophore structure of RhB.
As depicted from Fig. 8, the experimental results were tted
to pseudo-rst-order and all Ag
exhibit higher photocatalytic performance than single Ag
and b-AgVO nanowires. The apparent rate constant k was
3
VO
4
/b-AgVO
3
composites
3
VO
4
3
shown in inset. It can be seen that the composite with mole
ratios of 30% Ag VO /b-AgVO shows the highest value of
3
4
3
apparent rate constant k, which was 9 and 2.4 times higher than
pure b-AgVO and Ag VO . This indicates that the composite
3
3
4
Fig. 5 XPS spectra of 30% Ag
3
VO
4
/b-AgVO
3
composite (a) Ag 3d Fig. 7 Changes in UV-visible absorption spectra of 30% Ag
3 4
VO /b-
spectra, (b) V 2p spectra.
AgVO photocatalyst at different times under visible light irradiation.
3
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Fig. 10 Cycling runs in the photocatalytic degradation of RhB for the
3 4 3
30% Ag VO /b-AgVO .
Fig. 8 First-order kinetics of the photodegradation of RhB over b-
AgVO
illumination. The inset is the rate constant k of the photodegradation of
RhB over b-AgVO , Ag VO , and Ag VO /b-AgVO samples.
3 3 4 3 4 3
, Ag VO , and Ag VO /b-AgVO samples under visible light
Additionally, to further reveal the photocatalytic mechanism,
3
3
4
3
4
3
the trapping experiments were performed, as shown in Fig. 11.
Under visible illumination the photodegradation of RhB is
slightly inhibited by adding the IPA (hydroxyl radical scavenger)
and ammonium oxalate (hole scavenger), which indicates that
hydroxyl radical and hole are the main species that can
degenerate RhB.
In order to investigate the process of charge carriers trap-
ping, migration and separation efficiency, the PL spectra of b-
3 3 4 3 4 3
AgVO , Ag VO , and 30% Ag VO /b-AgVO samples under the
with 30% molar ratio is the most suitable for b-AgVO
Ag VO , which could boost the separation of charge carriers and
enhance the photocatalytic performance.
Furthermore, as is shown in Fig. 9, 30% Ag VO /b-AgVO
3
3
and
3
4
3
4
composite has weak adsorption and desorption. The surface
areas of b-AgVO3 and 30% Ag VO /b-AgVO composite were
3
4
3
2
ꢁ1
3
.096 and 4.610 m g , respectively. It was worthwhile to note
that the surface area of 30% Ag VO /b-AgVO composite
becomes larger with the Ag VO nanoparticles deposited on the
b-AgVO nanoribbons, which can provide more active sites and
excitation wavelength of 350 nm, as shown in Fig. 12. It was
generally acknowledged that the lower PL intensity indicates
that the higher separation capacity of charge carriers, which
results in higher photocatalytic activity. It was observed that the
main emission peak of b-AgVO , Ag VO , and Ag VO /b-AgVO
3
3
4
3
3
4
3
enhance photocatalytic activity.
3
3
4
3
4
The stability of photocatalysts is an important factor for the
further application. As is shown in Fig. 10, the photocatalytic
activity of the 30% Ag VO /b-AgVO composite still reached
composites all center at about 595 nm. Compared with pure b-
AgVO and Ag VO samples, the lower PL peak intensity of 30%
/b-AgVO composites implies that the interface between
and b-AgVO can migrates the photogenerate electrons
3
3
4
3
4
3
Ag
Ag
3
VO
VO
4
4
3
67%, even though it had been used 3 times.
3
3
and holes more effectively.
Fig. 9
photocatalyst at 393.15 K and the surface areas inset of b-AgVO
0% Ag VO /b-AgVO composite.
2 3 4 3
N adsorption–desorption isotherm of 30% Ag VO /b-AgVO
3
and Fig. 11 The plots of photogenerated carrier trapping in the system of
3
3
4
3
photodegradation of RhB under visible light irradiation.
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Scheme
3 4 3
1 Photocatalytic mechanism of 30% Ag VO /b-AgVO
toward the degradation of RhB.
3 3 4
Fig. 12 Photoluminescence (PL) spectra of b-AgVO , Ag VO , and
3
3
0% Ag
50 nm.
3 4 3
VO /b-AgVO samples under the excitation wavelength of
effectively, which is crucial for enhancing photocatalytic
activities.
3 4 3
Aer the photoreaction on the Ag VO /b-AgVO composite
photocatalyst, the photogenerated electrons of VB transferred to
3 4
In fact, the pathway of RhB degradation over Ag VO /b-
+
0
45
the CB of b-AgVO
3
could reduce the Ag to Ag nanoparticles
AgVO composite under visible light is rather complex. Based
3
0
(eqn (2a) and (2b)). However, Ag nanoparticles with SPR in the
on the above experimental results and photocatalytic degrada-
tion reports, the possible reactions are summarized by eqn (1)–
4).
visible light region could disrupt the ordered transfer of elec-
trons and holes of Ag VO /b-AgVO composite, which results in
3
4
3
(
the gradual declining of photocatalytic activity over Ag VO /b-
3
4
CBꢁ
+
AgVO3 hybrid. This is in agreement with decreased photo-
catalytic performance aer three cycling runs.
Ag
3
VO
4
+ hn / Ag
3
VO
4
(e
+ hVB
)
(1a)
(1b)
ꢁ
+
b-AgVO + hn / b-AgVO (e
+ hVB
)
3 4
In addition, the VB potential of Ag VO (2.325 eV vs. NHE)
3
3
CB
and b-AgVO
3
(2.48 eV vs. NHE) were more positive than the
+
Ag (in b-AgVO
CBꢁ
45
ꢁ
3
) + e
/ Ag
(2a) standard reduction potential of O /OH (0.4 eV vs. NHE) (3a),
2
ꢁ
O
2
/H
2
O (1.23 eV vs. NHE) (3b) and cOH/OH (1.55 eV vs. NHE)
Ag + hn / Ag (SPR)
(2b)
(3a)
(3b)
(3c). Therefore, holes on the VB of both Ag VO and b-AgVO
3 4 3
ꢁ
+
could react with H O and OH to form cOH, H and O2,
+
+
2
4h
VB + 2H
2
O / 4H + O
2
according to eqn (3a)–(3c). Thus, holes and cOH radicals play
important roles in the photocatalytic degradation of RhB, which
is in good agreement with the experimental result of trapping
experiment. Furthermore, the redox potential of RhB (ꢁ1.09 eV
+
ꢁ
+
4h
VB + 2OH / 2H + O
2
+
+
30
hVB + H O / cOH + H
(3c)
(4a)
2
3 4
vs. NHE) is more negative than the CB potential of Ag VO
*
ads
RhBads þ hn/RhB
(ꢁ0.045 eV vs. NHE) resulting in the self-sensitized degradation
of RhB according to eqn (4a)–(4c).
*
ꢁ
þ
RhB þ eCB /RhBads
(4b)
(4c)
ads
+
46
RhBads + cOH / N-ethyl rhodamine / CO + H O
2
2
4
Conclusions
In accordance with eqn (1)–(4) and the Scheme 1, the
possible mechanism of migration of carriers in the Ag VO /b-
AgVO composite heterostructures was discussed. Both Ag VO
and b-AgVO3 can be excited under visible light illumination
according to the UV-vis diffuse reectance spectra (eqn (1a) and
In summary, we have successfully synthesized Ag VO /b-AgVO
3
3
4
3
4
heterojunctions via chemical precipitation and hydrothermal
method. They show much better photocatalytic activity than
pure Ag VO and b-AgVO3 toward RhB degradation under
3
3
4
3
4
visible light and the 30% Ag
the highest. It is found that the photocatalytic activity increased
with the Ag VO amount increasing, which can be ascribed to
the matched energy structure in the Ag VO /b-AgVO hetero-
3 4 3
VO /b-AgVO composite exhibits
(
1b)). The electrons on the conduction band of Ag VO can
3 4
3
transfer into the conduction band of b-AgVO and the holes on
3
4
the valence band of Ag
of b-AgVO , because the conduction band of Ag
than b-AgVO and the valence band of Ag VO is positive than b-
So, photoinduced electrons and holes can separate
3
VO
4
can transfer into the valence band
3
4
3
3
3
VO is negative
4
junction that can efficiently enhanced separation of photoin-
duced carriers. The holes and hydroxyl radicals play signicant
roles in the photocatalytic degradation of RhB under visible
light.
3
3
4
47–50
3
AgVO .
27520 | RSC Adv., 2017, 7, 27515–27521
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4 X. Lin, D. Xu, J. Zheng, M. S. Song, G. B. Che, Y. S. Wang,
Y. Yang, C. Liu, L. N. Zhao and L. M. Chang, J. Alloys
Compd., 2016, 688, 891–898.
Acknowledgements
The authors would like to thank the partial nancial support
from the National Natural Science Foundation of China (No. 25 X. Lin, Y. S. Wang, J. Zheng, C. Liu, Y. Yang and G. B. Che,
51272052 and No. 50902040).
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