A facile synthesis of Ag/AgCl hybrid nanostructures with tunable morphologies and compositions as advanced visible light plasmonic photocatalysts

Article abstract of DOI:10.1039/c6dt00993j

This paper describes a simple and fast aqueous-phase route to the synthesis of Ag/AgCl hybrid nanostructures. These hybrid nanostructures were synthesized by reduction of AgCl nanoparticles with controlled shapes prepared by reacting Ag⁺ with Cl^- in the presence of polyethyleneimine (PEI) in an aqueous-phase. We could easily control the morphology and composition of the nanostructures by varying the experimental conditions, including the reaction temperature and the amount of the reducing agent. The as-synthesized Ag/AgCl hybrid nanostructures exhibited enhanced photocatalytic activity and stability during the degradation of methyl orange under visible light irradiation because of their strong surface plasmon resonance (SPR) effect.

Full text of DOI:10.1039/c6dt00993j

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Facile synthesis of Ag/AgCl hybrid nanostructures with tunable
morphologies and compositions as advanced visible light
plasmonic photocatalysts
Received 00th January 20xx,
Accepted 00th January 20xx
Aasim Shahzad,a Woo-Sik Kim*a and Taekyung Yu*a
DOI: 10.1039/x0xx00000x
This paper describes a simple and fast aqueous-phase route to the synthesis of Ag/AgCl hybrid nanostructures. These
hybrid nanostructures were synthesized by reduction of AgCl nanoparticles with controlled shapes prepared by reacting
Ag+ with Cl− in the presence of polyethyleneimine (PEI) in an aqueous-phase. We could easily control the morphology and
composition of the nanostructures by varying the experimental conditions, including the reaction temperature and the
amount of reducing agent. The as-synthesized Ag/AgCl hybrid nanostructures exhibited enhanced photocatalytic activity
and stability during the degradation of methyl orange under visible light irradiation because of their strong surface
plasmon resonance (SPR) effect.
www.rsc.org/
photocatalysts.15,16 Over the past decades, considerable efforts
have been devoted to engineering photocatalysts to enhance
their visible light absorption coefficient, including ion
Introduction
Noble metal nanostructures including Au, Ag, and alloy-based
Au or Ag have been investigated as enablers for a variety of
applications involving light because of their plasmon
resonance.1−4 With tight control over the nanostructures in
terms of size and morphology, the phenomenon of plasmon
resonance gives rise to important applications such as
colorimetric sensors,5 conversion of water to clean hydrogen
gas by photocatalytic water splitting,6 conversion of carbon
dioxide to gaseous hydrocarbons,7,8 creation of self-cleaning
doping,17,18 noble metal deposition,19 and anchoring organic
dye molecules on the surface of photocatalysts.20 Although
there has been some progress enhancing visible light
photocatalytic efficiency, the limited amount and the easy
leaching of dopants may adversely affect the activity and
chemical stability of photocatalysts.21−23 In addition, dye-
sensitized photocatalysts often suffer from self-degradation of
the dye molecules.24 Besides TiO2-based photocatalysts, some
research groups have fabricated novel visible light catalysts
such as Bi2WO6,25 CFe2O4/TaON,26 and Cu2(OH)PO4.27 However,
these photocatalysts still have some drawbacks such as low
activity and poor stability. Therefore, developing a new
efficient visible light photocatalyst with good activity, stability,
and recyclability still remains a significant challenge.
surfaces9 and oxidation of organic contaminants.10
photocatalyst, which can absorb light and accelerate
A
a
photoreaction, is the most important part of photocatalysis.
Photocatalysts also ideally have high absorption of sunlight or
visible light, high reactivity, are non-toxic, photostable, and
chemically inert.11 Typically, photocatalysts are solid
semiconductors with the ability to create electron-hole pairs
when irradiated by light.
Plasmonic nanoparticles of noble metals with high
absorption coefficients in the visible region can serve as an
alternative class of sensitizers to enhance the absorption of
semiconductors, which are mainly influenced by size and
morphology.28,29 Moreover, the resulting composite catalysts
resist degradation during the photoreaction. Various research
on noble metal/supporting material composite photocatalysts
has been reported, for instance, Ag/TiO2/graphene,30
Au/TiO2,31 Ag/ZnO,32 and Ag/AgCl.33−36 Among them, Ag/AgCl
Recently, TiO2-based photocatalysts have been intensively
investigated since the discovery of its water electrolysis
behavior.12 TiO2–based photocatalysts have a large band gap,
larger than 3.2 eV, which enables them to be chemically stable
but restricts their response to the UV fraction of solar energy
(about 4%) at the same time, leading to low efficiency in visible
and near infrared regions.13,14 Furthermore, the fast
recombination rate of photogenerated electron-hole pairs also
promises high activity and enhanced stability as
a
metal/semiconductor composite photocatalyst because of
their fast separation and transportation of photogenerated
electron-hole pairs.37 Multifarious approaches have been
designed to fabricate Ag/AgCl composite material such as an
ion-exchange reaction between Ag+ and Cl− followed by UV or
laser light reduction,36,38 polyol reduction,37 hydrothermal
synthesis,39 and thermal decomposition in ionic liquid.40
decreases
the
catalytic
efficiency
of
TiO2–based
Electronic Supplementary information available: See DOI: 10.1039/x0xx00000x
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However, most of these reported procedures require tedious The morphology and composition of the sample were
reaction steps, long reaction times, high reaction recorded by SEM (LEO SUPRA 55) and EDS (INCA, Oxford
temperatures, or have poor control of the size and Company). TEM images were captured using a JEM-2100F
morphology of the Ag/AgCl structures due to the high reaction microscope operated at 200 kV. The UV-vis spectra were
speed between the silver and the chloride ions. In addition, recorded using
controlling the composition of Ag and AgCl in the composite spectra were taken using a Jasco FT-IR-6100. The powder XRD
material is the most challenging aspect of obtaining high patterns were obtained using Rigaku D-MAX/A
a Jasco UV-vis spectrophotometer. FT-IR
a
visible light absorbability of AgCl as well as catalytic activity in diffractometer at 35 kV and 35 mA. XPS measurements were
Ag nanomaterials. To our knowledge, the maximum level of Ag conducted using a Thermo Scientific K-Alpha spectrometer
in the Ag/AgCl hybrid structures is limited to 80% in all with an Al Kα X-ray source. TGA was performed using a TGA
previous reports.
Q5000 IR thermal analyzer.
Herein, we report a simple, economic, and fast aqueous-
phase route for the shape-controlled synthesis of AgCl Evaluation of photocatalytic activity
nanoparticles and their transformation to Ag/AgCl hybrid
Methyl orange (MO) was chosen as the target organic
nanostructures, which are efficient, stable visible light
photocatalysts. These hybrid nanostructures are synthesized
by reducing AgCl nanoparticles with controlled shapes
prepared by reacting Ag+ with Cl− in the presence of PEI in an
compound to probe the visible light driven photocatalytic
performance of various prepared photocatalysts. 30.0 mg of
the respective photocatalysts were dispersed in 50 mL of MO
aqueous solution (20 mg/L). The mixture was stored in
darkness while being stirred for 30 min to establish an
adsorption-desorption equilibrium of MO molecules on the
photocatalysts. The photocatalytic test was performed under
visible light irradiation using a 200 W mercury xenon lamp
(Raynics, Korea) with a UV cut-off filter (> 400 nm). Aliquots of
the suspension (2.0 mL) were taken out from the reaction
system at different reaction times, and centrifuged at 10,000
rpm for 5 min to remove the photocatalysts from the solution.
aqueous-phase.
The
synthesized
Ag/AgCl
hybrid
nanostructures were composite structures with 5−25 nm
nanoparticles decorating 150−350 nm-sized particles or hollow
structures with boxes and cages. We could easily control the
morphology and composition of the nanostructures by varying
the experimental conditions, including the reaction
temperature and the amount of reducing agent. Interestingly,
we were able to control the Ag level in the Ag/AgCl hybrid
nanostructure at an Ag level up to 97.4% within 5 min of
reaction time. The as-synthesized Ag/AgCl hybrid
nanostructures exhibited enhanced photocatalytic activity and
stability during the degradation of methyl orange under visible
light irradiation because of their strong surface plasmon
resonance (SPR) effect.
Supernatants were transferred to
a UV-vis cuvette for
measuring their absorption spectra in the range of 300−800
nm. For recycling experiments, the photocatalysts were
centrifuged, washed, and collected. For subsequent recycling
tests, all the procedures were the same as the first cycle.
Results and discussion
Experimental section
The AgCl nanoparticles were synthesized via a precipitation
reaction between AgNO3 and NaCl in the presence of
Synthesis of AgCl nanoparticles
In a typical synthesis, PEI (40 mg, MW 750,000, 50 wt% polyethyleneimine (PEI) as a stabilizer in an aqueous-phase at
solution in water, Aldrich) was dissolved in deionized water (10 different reaction temperatures. Fig. 1a−d show scanning
mL) and heated to 30 °C under magnetic stirring, and 0.1 mL of electron microscopy (SEM) images of the AgCl nanoparticles
1 M aqueous AgNO3 (Aldrich) solution was added to the synthesized at 30 °C, 50 °C, 70 °C, and 90 °C, indicating that
reaction solution. Then, 1 M aqueous solution of NaCl (0.25 these nanoparticles have semi-spherical, spherical, truncated-
mL, Aldrich) was added into the reaction solution rapidly using cubic, and cubic shapes, respectively. The colors of aqueous
a pipette. The resulting mixture was heated and stirred for 3 dispersions of the AgCl nanoparticles were milky (30 °C), dark
min, resulting in the formation of milky dispersions containing pink (50 °C), amber (70 °C), and dark yellow (90 °C),
AgCl nanoparticles. The products were collected by respectively (Fig. S1†), and all the nanoparticles exhibited a
centrifugation and washed with deionized (DI) water three strong absorption peak at 241 nm which corresponds with a
times.
direct bandgap of AgCl (5.15 eV) and a weak peak from an
41
indirect bandgap (382 nm, 3.25 eV), as shown in Figure S2†.
Synthesis of Ag/AgCl hybrid nanostructures
Average sizes of the AgCl nanoparticles were 154.2 ± 26.3 nm
for semi-spheres synthesized at 30 °C, 191.2 ± 28.4 nm for
spheres synthesized at 50 °C, 204.7 ± 29.8 nm for truncated
cubes synthesized at 70 °C, and 344.2 ± 44.4 nm for cubes
synthesized at 90 °C, revealing that the size of the AgCl
nanoparticles gradually increased with increasing reaction
The as-synthesized AgCl nanoparticles were re-dispersed in 5
mL of DI water, and a 10 mM aqueous solution of NaBH4 (0.1
mL to 2.0 mL) was then added under magnetic stirring at room
temperature. The color of the resulting solution immediately
changed from red to green, showing the formation of Ag/AgCl.
After 2 min, the product was collected by centrifugation.
temperature (Figure S3†
).42 Powder X-ray XRD patterns of the
AgCl nanoparticles show the presence of diffraction peaks at
27.9°, 32.3°, 46.3°, 54.9°, 57.5°, and 67.4°, which can be
Characterization
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assigned to (111), (200), (220), (311), (222), and (400) planes of
face-centered cubic (fcc) AgCl (Figure S4 Fm3m, a = 5.5491Å,
In a recent report on the synthesis of Ag nanoparticles using
PEI as a stabilizer, it was demonstrated that non-bonding
electrons of the amine group in PEI interacted with Ag+ to form
a PEI-Ag+ complex in the aqueous phase, thus controlling the
growth rate of the Ag nanoparticles (Fig. 2).4,43 In the present
research, we believe that PEI serves as a multi-functional
stabilizer to modulate the reaction rate between Ag+ and Cl− by
formation of a PEI-Ag+ complex and nano-sized AgCl particles
by capping the surface of the particles. To validate the
existence of coordination, FT-IR analysis of PEI without Ag+ was
†,
Joint Committee on Powder Diffraction Standards (JCPDS) file
no. 31-1238), respectively.
Fourier transform infrared (FT-IR) transmission spectrum of
the AgCl nanoparticles exhibited a distinct band at 1645 cm-1,
which was assigned to bending modes of amine groups (-N-H).
The absorption peaks at 1260 and 1022 cm-1 were assigned to
the stretching bands -C-H, and -C-N, respectively (Fig. S5a†).
Thermal gravimetric analysis (TGA) results of the AgCl
nanoparticles show around 21% weight loss at as high as 600
performed (Fig. S5a†
). In the absence of Ag+ a weak band at
1652 cm-1 was observed. When PEI was mixed with AgNO3, we
found small shifting of the absorption bands of -N-H bending
(from 1652 to 1645 cm-1) and -C-N stretching (from 1043 to
1022 cm-1). There observation were well matched with
previous reports on the formation of amine-metal
complexes.44,45 When the synthesis was conducted in the
absence of PEI, micrometer-sized agglomerated AgCl particles
were formed, demonstrating that PEI played a pivotal role in
°C, with the weight remaining stable afterwards (Fig. S5b†).
Both FT-IR and TGA analysis confirm the presence of PEI on the
surface of the AgCl nanoparticles.
the formation of AgCl nanoparticles (Fig. S6†).
The morphologies of the AgCl nanoparticles changed from
semi-spheres to cubes when the reaction temperature was
increased from 30 °C to 90 °C while keeping other
experimental conditions unchanged (Fig. 1a). In order to
obtain better understanding, we compared the intensity ratio
of I(200)/I(111) in the XRD data of the AgCl nanoparticles. In the
JCPDS file, the intensity ratio of I(200)/I(111) is about 2.0 (JCPDS
file no. 31-1238). The peak intensity ratio of the AgCl semi-
spheres synthesized at 30 °C was 1.95, while the AgCl
nanocubes exhibited a ratio of around 35.6, supporting the
Fig. 2 Schematic illustration of reaction pathways for the
synthesis of Ag/AgCl hybrid nanostructures.
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SEM images (Fig. S4†). These SEM and XRD analyses suggest 0.3 mL of NaBH4 solutions reacted with the AgCl nanoparticles,
that the AgCl nanoparticles grow mainly along the <100> we found that small Ag nanoparticles with sizes of 5−10 nm
direction at higher temperatures because the {100} facets of (Ag/AgCl-0.1) and 15−25 nm (Ag/AgCl-0.3) were attached on
AgCl possess minimum surface energy and Cl− ions in the {100} the surface of AgCl nanoparticles. They looked like dendrite
facets are saturated by Ag+ ions.36
structures (Fig. 3a and b). Upon further increasing the amount
To fabricate the Ag/AgCl hybrid nanostructures, we reduce of reducing agent to 0.5 mL and 1.0 mL, a small portion of
AgCl nanoparticles using NaBH4 at room temperature (Fig. 2). hollow sphere and hollow cage particles started to be
Fig. 1e−h show the SEM images of Ag/AgCl hybrid observed while the major product still consisted of Ag
nanostructures prepared by reacting 2.0 mL of NaBH4 (10 mM) nanoparticles decorating AgCl nanoparticles (Fig. 3c and d).
with AgCl nanoparticles, as shown in Fig. 1a−d. The SEM image Under the reaction conditions using 1.5 mL and 2.0 mL of
shown in Fig. 1e shows the formation of hollow cages with NaBH4 solution as a reducing agent, the SEM images show the
sizes around 132.3 ± 18.2 nm. In Fig. 1f−h, we observed the formation of only nanostructures with hollow interior
formation of decorated hybrid structures exhibiting morphology (Fig. 3e and f). A transmission electron microscopy
morphologies that include spherical (167.9 ± 23.8), truncated (TEM) image and energy dispersive X-ray (EDX) elemental
cube (185.6 ± 27.2), and cube (315.7 ± 41.6) with 10−25 nm- mapping data of the Ag/AgCl-2.0 clearly show the formation of
sized small Ag nanoparticles, respectively. The XRD patterns of hollow cages at high NaBH4 concentration (Fig. 3g−i).
these Ag/AgCl hybrid nanostructures shows the presence of
The composition of the Ag/AgCl hybrid nanostructures was
additional (111) and (200) planes of face-centered cubic (fcc) analyzed using energy dispersive X-ray spectroscopy (EDS).37
metallic Ag (Fm3m, a = 4.086 Å, JCPDS file no. 04-0783), The atomic ratio of Ag to AgCl increased from 0 (AgCl
indicating the formation of Ag and AgCl crystal structures (Fig. nanoparticles) to 36.61 (Ag/AgCl-2.0), indicating that around
S7†
).
97.34% of the AgCl was reduced to Ag (Table S1†). The optical
The morphology and composition of the Ag/AgCl hybrid absorption spectra taken from an aqueous suspension of the
nanostructures could be easily controlled by varying the synthesized Ag/AgCl hybrid nanostructures show the presence
concentration of the reducing agent. SEM images in Fig. 3a-f of strong plasmon resonance peaks (SPR) around 415−420 nm
show the morphology change of the Ag/AgCl hybrid (Fig. S8†). The absorption peak rises in intensity from Ag/AgCl-
nanostructures synthesized by reacting different volumes of 10 0.1 to 2.0, showing more absorption of visible light due to the
mM NaBH4 solution with AgCl semi-spheres synthesized at 30 enhanced Ag. Metallic Ag nanostructures could have a strong
°C (The volumes of 10 mM NaBH4 solution were 0.1 mL, 0.3
interaction with incident light because the conduction
mL, 0.5 mL, 1.0 mL, 1.5 mL, and 2.0 mL, respectively, and these electrons on the metal surface undergo a collective oscillation
products are noted as Ag/AgCl-0.1 to 2.0). When 0.1 mL and upon excitation with incident light, known as surface plasmon
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resonance. Due to this strong SPR-effect, Ag nanoparticles can respectively, which corresponds to Ag+ in the AgCl. The other
have upto 10-fold effective extinction cross section than their set included a Ag 3d5/2 peak at 368.0 and a Ag 3d3/2 peak at
physical cross section.46
374.2, which can be assigned to metallic Ag.47 In addition, the
The XRD patterns of the Ag/AgCl hybrid nanostructures intensity of XPS peaks of Cl− decreased compared with those of
show the presence of (111) and (200) planes of face-centered the AgCl nanoparticles, indicating a low portion of AgCl in the
cubic (fcc) metallic Ag (JCPDS file no. 04-0783), indicating the product (Fig. 4d). In the Ag/AgCl-2.0, the intensity peaks of Ag
formation of Ag and AgCl crystal structures (Fig. 3j). were much higher than those of the Ag+ species, and the peaks
Interestingly, the diffraction peaks of AgCl gradually decreased for Cl− species also decreased to a minimum (Fig. 4e and f). The
in intensity and the peak from the (111) plane of AgCl finally corresponding XPS spectra indicates that the atomic
disappeared in the Ag/AgCl-2.0, while that of Ag at 38.1° (111) percentages of Ag and Cl on the surface of the samples were
rose from Ag/AgCl-0.1 to 2.0. The atomic percentages of Ag 54 and 46 % for AgCl, 85.02 and 14.97 % for Ag/AgCl-0.5, and
and Cl in the nanostructures were also calculated through 99.6 % and 0.4 % for Ag/AgCl-2.0, respectively.
normalization of peak areas and values were, 50 and 50 % for
The photocatalytic performance of the Ag/AgCl hybrid
AgCl, 82.36 and 17.64 % for Ag/AgCl-0.5, and 97.73 % and 2.27 nanostructures was studied during the degradation of methyl
% for Ag/AgCl-2.0, respectively, which were well matched with orange (MO) under illumination by visible light (Fig. 5a). We
EDS analysis.
investigated the kinetic process of photodegradation by
monitoring the intensity of the absorption peak at 464 nm
associated with MO as a function of time. Fig. S9† shows the
photodegradation curves of MO when using Ag/AgCl-0.5 as a
photocatalyst. After adding the photocatalyst, the absorption
peak at 464 nm rapidly dropped in intensity as the
photocatalytic reaction proceeded, revealing that MO
molecules can be effectively decomposed under visible light
illumination in the presence of Ag/AgCl hybrid nanostructures.
Fig. 5 a) Schematic illustration of the proposed degradation
mechanism of MO using Ag/AgCl plasmonic photocatalysts.
b−c) Photocatalyꢀc degradaꢀon of MO using the Ag/AgCl
hybrid nanostructures. b) Normalized concentration of MO as
a function of reaction time in both the linear and logarithmic
scale. c) The normalized concentration of the MO for different
photocatalysts on a linear scale. d) Photodegradation kinetics
of MO for five consecutive cycles with the same batch of
Ag/AgCl-0.5.
Fig. 4 XPS spectra of a−b) the AgCl nanoparꢀcles, as shown in
Fig. 1b, c−d) Ag/AgCl-0.5, as shown in Fig. 2c, and e−f) Ag/AgCl-
2.0, as shown in Fig. 3f.
These observations were further confirmed by X-ray
photoelectron spectroscopy (XPS) investigations. As shown in
Fig. 4a, two distinct peaks at 367.3 and 373.2 eV corresponding
to the binding energies of the Ag 3d5/2 and Ag 3d3/2 core levels
were observed in the AgCl nanoparticles prepared at 30 °C,
indicating ionic Ag+ was a major species in the product. The Cl
2p core level spectrum included a Cl 2p3/2 peak at 197.6 and a
Cl 2p1/2 peak 199.2 eV, respectively, which can be assigned to
Cl− (Fig. 4b). In the Ag 3d XPS core level spectrum of Ag/AgCl-
0.5, two sets of 3d peaks were observed (Fig. 4c). One set
consisted of Ag 3d5/2 and Ag 3d3/2 peaks at 367.5 and 373.5 eV,
After adding the photocatalyst, the absorption peak at 464 nm
rapidly dropped in intensity as the photocatalytic reaction
proceeded, revealing that MO molecules can be effectively
decomposed under visible light illumination in the presence of
Ag/AgCl hybrid nanostructures. Organic dyes in aqueous
solution often form aggregates of dimers or high polymers,
which are absorbed in the short wavelength region, and
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sometimes the polymer or surfactants detach from the surface Fig. 6 a) SEM image and b) XRD patterns of the Ag/AgCl-0.5
of the catalysts, which often affects the photocatalysis photocatalyst after five successive photocatalytic reactions.
process.34 We could not observe any absorption feature of the
In addition to efficiency, stability and/or recyclability,
degradation products of MO molecules in the scanned spectral photocatalysts are also important for applications because
region during the degradation process, indicating good photocatalysts often lose their performance due to photo-
structural integrity of our PEI-stabilized Ag/AgCl hybrid corrosion.35 To test the stability of the Ag/AgCl-0.5 hybrid
nanostructures during the harsh photocatalytic environment. nanostructures, recycling photodegradation experiments for
Fig. 5b plots the dependence of the concentration (C) of MO MO were carried out five times (Fig. 5d). The catalyst did not
normalized against the concentration (C0) at the start of the show a significant decrease in photocatalytic performance
reaction using Ag/AgCl-0.5 as photocatalysts, showing that the after repeated use. The SEM image and XRD pattern of
decomposition reaction of MO has first order kinetics:
dC/d = - C,
(1)
Ag/AgCl-0.5 recycled five times are almost identical to the
original samples (Fig. 6). These observations indicate that
neither the morphology nor the phase composition is changed
during recycling tests, and the Ag/AgCl hybrid nanostructures
exhibit good stability against photo-corrosion.
t
k
ln(C/C0) = -kt
,
(2)
We also investigated the photocatalytic performance of
where k is the rate constant. The rate constant was estimated Ag/AgCl hybrid nanostructures using degradation of
to be 0.1638 min−1 for MO degraded using Ag/AgCl-0.5. For Rhodamine B (RhB). The photocatalytic conducting parameters
comparison, we also carried out decomposition of MO using were the same as that of MO, as shown in Fig. 5b. The rate
Ag/AgCl-0.1, 0.3, 1.0, and commercial TiO2 (P-25) which is a constant was estimated to be 0.1894 min−1 (Fig. 7), indicating
reference photocatalyst under visible light irradiation (Fig. 5c). that the Ag/AgCl hybrid nanostructures could be used as
The rate constants were estimated to be 0.0108 min-1 for catalyst in various photocatalytic degradation reaction.
Ag/AgCl-0.1, 0.0324 min-1 for Ag/AgCl-0.3, 0.0074 min-1 for
Ag/AgCl-1.0, and 0.0001 min-1 for P-25 (Fig. S10
†). Moreover,
the decomposition rate of MO by Ag/AgCl-0.5 was faster than
Ag/AgCl-0.1, 0.3, 1.0, and P-25 by factors of 15, 5, 22, and
1638, respectively. These results indicate that Ag/AgCl-0.5
exhibits the best performance. The excellent visible light
driven photocatalytic performance of Ag/AgCl-0.5 hybrid
nanostructures can be attributed to the positively synergistic
effect between metallic Ag and semiconducting AgCl. Although
Ag/AgCl-1.0 contains a large amount of metallic Ag (~ 92.58%)
compared with Ag/AgCl-0.5, the lower level of semiconducting
AgCl would limit MO degradation.48
Fig.
7 a) UV-vis absorption spectra for photocatalytic
degradation of RhB molecules over Ag/AgCl-0.5 hybrid
nanostructures under visible light irradiation. b) Normalized
concentration of RhB as a function of reaction time in both the
linear and logarithmic scale.
Conclusions
In summary, we presented a simple, economic, and fast
aqueous-phase route to shape controlled synthesis of AgCl
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nanoparticles and their transformation to Ag/AgCl hybrid
nanostructures that are efficient and stable visible light
photocatalysts. The shapes, sizes, and morphology of AgCl
nanocrystals can be easily controlled by varying the reaction
temperature, and the Ag/AgCl hybrid nanostructures were
easily synthesized by reducing the AgCl nanoparticles at room
temperature during a 5 min reaction time. We could easily
control the morphology and composition of the
nanostructures by varying the experimental conditions,
including the reaction temperature and the amount of
reducing agent. The as-synthesized Ag/AgCl hybrid
nanostructures exhibited enhanced photocatalytic activity and
stability during the degradation of methyl orange under visible
light irradiation. Furthermore, we expect that this control over
the morphology and composition of the Ag/AgCl hybrid
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Acknowledgements
This research was supported by the Basic Science Research
Program through the National Research Foundation of Korea
(NRF) funded by the Ministry of Science, ICT & Future Planning
(2014R1A5A1009799). This work was also supported by a grant
from Kyung Hee University in 2015 (KHU-20150516).
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DOI: 10.1039/C6DT00993J
ARTICLE
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Graphical Abstract
Ag/AgCl plasmonic photocatalysts are synthesized by a simple
and rapid method in an aqueous-phase. We could easily
control the morphology and composition of the
nanostructures by varying the experimental conditions. The
Ag/AgCl hybrid nanostructures exhibited enhanced
photocatalytic activity and stability toward the degradation of
methyl orange under the visible light irradiation because of
their strong surface plasmon resonance (SPR) effect.
8 | J. Name., 2012, 00, 1-3
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