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Facile Preparation of Uniform Nanocomposite Spheres with Loading Silver Nanoparticles on Polystyrene-Methyl Acrylic Acid Spheres for Catalytic Reduction of 4-Nitrophenol Guangfu Liao, Jun Chen, Weiguo Zeng, Chunhan Yu, Changfeng Yi, and Zushun Xu J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.6b09356 • Publication Date (Web): 27 Oct 2016 Downloaded from http://pubs.acs.org on October 27, 2016

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The Journal of Physical Chemistry C is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

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The Journal of Physical Chemistry

Facile Preparation of Uniform Nanocomposite Spheres with Loading Silver Nanoparticles on Polystyrene-Methyl Acrylic Acid Spheres for Catalytic Reduction of 4-Nitrophenol Guangfu Liao†, Jun Chen†, Weiguo Zeng†, Chunhan Yu†, Changfeng Yi† and Zushun Xu*,† †

Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials; Ministry of

Education Key Laboratory for The Green Preparation and Application of Functional Material, Hubei University, Wuhan, Hubei 430062, China ABSTRACT: A simple, mild and green route is developed for the preparation of uniform polystyrene-methyl acrylic acid/silver (PSMAA/Ag) nanocomposite spheres with high catalytic activities. In this approach, monodisperse polystyrene-methyl acrylic acid (PSMAA) spheres are used as polymeric matrices, silver precursor-[Ag(NH3)2]+ ions are then adsorbed onto the surfaces of PSMAA spheres due to the strong electrostatic attraction between carboxyl groups (electronegative) and [Ag(NH3)2]+ ions (electropositive). Meantime, [Ag(NH3)2]+ ions are reduced to Ag nanoparticles and simultaneously protected by PVP on the surface of PSMAA spheres. In this way, the PSMAA/Ag nanocomposite spheres with loading Ag nanoparticles on PSMAA spheres are prepared in aqueous media without any toxic reagents used during the preparation process. Ag nanoparticles uniformly distribute on the surfaces of PSMAA spheres with its size ranging from 8 to 24 nm. Moreover, the coverage degree of Ag nanoparticles on PSMAA spheres increases with the increasing of concentration of silver precursor-[Ag(NH3)2]+ ions. In addition, thermal analysis results show that the prepared PSMAA/Ag nanocomposite spheres exhibit improved thermal stabilities and glass translation temperature when compared to the related neat PSMAA spheres. Catalytic studies indicate that the prepared PSMAA/Ag nanocomposite spheres exhibit a high catalytic activities and

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good recyclability for the reduction of 4-nitrophenol, rendering a potential use in the fields of catalytic reduction of 4-nitrophenol to 4-aminophenol. INTRODUCTION During recent decades, nanostructural materials have received increasing attention in many aspects due to their superior chemical, physical, and biological properties when compared to their bulk counterparts,1-4 especially those of metal nanoparticles and metal oxides, such as copper,5 gold,6 silver,7 ferriferrous oxide,8 titanium oxide,9 zinc oxide,5 etc. Among these nanoparticles, Ag nanoparticles are widely used as an effective catalytic material because Ag nanoparticles, with high surface area, enable a large number of atoms on their surfaces so as to be accessible to the environment's media.10 Unfortunately, single Ag nanoparticles used as catalytic material have a series of problems such as easy oxidation, easy aggregation and high cost. In order to solve these problems, many different methods have been developed, and a significant attempt to overcome these drawbacks is the incorporation of Ag nanoparticles into or onto various matrices.11-12 For example, polymer spheres13 and inorganic oxides (such as silica,14 titanium oxide,15 ferriferrous oxide,16 and iron oxide17) have been used as matrices for Ag nanoparticles. Generally, the preparation process of these Ag nanocomposites consists of two steps. Firstly, the surface of matrices is activated with the help of some compounds or metal nanoparticles such as tin dichloride dihydrate, gold, palladium, etc. Then Ag nanoparticles are decorated onto the surface of these matrices.18-19 In this case, additional reagents such as reducing agents, surfactants, and stabilizers must be added in order to reduce silver precursors to silver nanoparticles and prevent the Ag nanoparticles from aggregation.20-22 However, these additional reagents will maintain as impurities in the final system, and potentially lead to environmental

pollution

and

biological

hazards.23-24

Therefore,

environmentally friendly method is highly worth considering.


a

straightforward

and

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Polyvinylpyrrolidone (PVP) has been proved to be a good reducing agent and stabilizing agent for the preparation of Ag nanocomposites.25-29 Moreover, it also has superior properties such as chemical and biological inertness, good initial tack, low toxicity, and so on.30-31 Recently, Deng et al.26 has prepared PS/Ag nanocomposite spheres by using PVP as stabilizing agent and reducing agent. Their method is inherently an environmentally friendly method because of the absence of any toxic reagents. Deficiently, the concentrated sulfuric acid was used to activate the surface of PS spheres which increases the difficulty of the experiment. For example, the purification process of the sulfonated PS is slightly complex and dangerous, because the concentrated sulfuric acid is a strongly corrosive chemical reagents. Therefore, it is important to seek a better matrice. By direct copolymerization, PSMAA spheres are formed of styrene and methyl acrylic acid with emulsifier-free emulsion polymerization. Not only can the PSMAA spheres provide abundant active functional carboxyl groups to activate the surface of PSMAA spheres, but also the preparation process of PSMAA spheres is simple and mild.32-33 Thus PSMAA spheres are a fairly ideal matrice for the preparation of Ag nanocomposites. Herein, we present a simple, mild and green approach to prepare uniform PSMAA/Ag nanocomposite spheres through utilizing PSMAA spheres as polymeric matrices and PVP as reducing agent and stabilizing agent. In this approach, PSMAA spheres are prepared by emulsifier-free emulsion copolymerization of styrene and methyl acrylic acid initially. Subsequently, PSMAA spheres are used as polymeric matrices and silver precursor-[Ag(NH3)2]+ ions are adsorbed onto the surfaces of PSMAA spheres due to the strong electrostatic attraction between carboxyl groups (electronegative) and [Ag(NH3)2]+ ions (electropositive). Finally, [Ag(NH3)2]+ ions are reduced to Ag nanoparticles and simultaneously protected by PVP on the surface of PSMAA spheres. This approach has four advantages deserving to be emphasized: (1) the preparation process of PSMAA spheres is simple and mild without further decoration of PSMAA spheres for the prepared



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PSMAA spheres have had abundant active functional carboxyl groups; (2) a great number of functional carboxyl groups on the surface of PSMAA spheres provide an excellent platform to absorb silver precursor-[Ag(NH3)2]+ ions and then reduce silver precursor-[Ag(NH3)2]+ ions into Ag nanoparticles with PVP; (3) the PSMAA/Ag nanocomposite spheres are prepared in aqueous media without any toxic reagents used during the preparation process; (4) the coverage degree of Ag nanoparticles on PSMAA spheres increases with the increasing of concentration of silver precursor-[Ag(NH3)2]+ ions. Therefore, our method inherently provides a simple, mild, environmentally friendly and controllable route for preparation of PSMAA/Ag nanocomposite spheres. In addition, the prepared PSMAA/Ag nanocomposite spheres can be used as a catalytic material for the reduction of 4-nitrophenol to 4-aminophenol with NaBH4. EXPERIMENTAL Materials. Styrene (St) and methyl acrylic acid (MAA) was bought from Aladdin Reagent Inc., Shanghai, China and the inhibitor was removed by vacuum distillation. Polyvinylpyrrolidone (PVP, Mw=40000mol/g), absolute ethanol, silver nitrate (AgNO3, ≥99.8 %), potassium persulfate (KPS), ammonia and 4-nitrophenol were purchased from Sinopharm Chemical Reagent Co., Ltd, China. Deionized water from a Milli-Q water system was used throughout the experiments. Preparation of monodisperse PSMAA spheres. Monodisperse PSMAA spheres were prepared by emulsifier-free emulsion polymerization method.34 In brief, St (15 mL), MAA (1 mL), and deionized water (125 mL) were added into a 250 mL four-necked flask equipped with mechanical stirrer, reflux condenser, nitrogen inlet and temperature controller. The solution was deoxygenated by bubbling nitrogen gas at room temperature for 30 min. Then, the reaction was heated to 70 °C and KPS aqueous solution (0.0625 g KPS in 2.5 mL of deionized water) was added to start the polymerization reaction. After 24 h, the PSMAA spheres were obtained. The obtained


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product was dialyzed for two weeks and then as a stable dispersion in deionized water with ca. 5wt % solid content. Preparation of monodisperse PSMAA/Ag nanocomposite spheres. PSMAA dispersion (4g), PVP (1g), and deionized water (30 mL) were added into 100 mL four-necked flask equipped with mechanical stirrer, reflux condenser, nitrogen inlet and temperature controller. Then, 10 mL of freshly prepared aqueous solution of [Ag(NH3)2]+ (0.3 to 0.5 M) was quickly added into the above mixture. The solution was deoxygenated by bubbling nitrogen gas at room temperature for 60 min. Finally, this mixture was kept at 70 °C and stirred for 7 h under the atmosphere of nitrogen. The final products were separated by centrifugation, and washed with an excess amount of deionized water and absolute ethanol several times and then dried in vacuum at 50 °C for 24 h. Herein, three PSMAA/Ag nanocomposite spheres with different concentrations of [Ag(NH3)2]+ ions were prepared, the concentrations of [Ag(NH3)2]+ ions were 0.3 M, 0.4 M, 0.5 M, marking PSMAA-1 nanocomposite spheres, PSMAA-2 nanocomposite spheres, PSMAA-3 nanocomposite spheres, respectively (Table 1). Table 1. Abbreviations for PSMAA/Ag nanocomposite spheres Sample

PSMAA (g)

PVP (g)

H2O (mL)

[Ag(NH3)2]+ (M)

PSMAA-1

4

1

30

0.3

PSMAA-2

4

1

30

0.4

PSMAA-3

4

1

30

0.5

Characterization. Fourier transform infrared spectroscopy (FTIR) analysis of the samples was taken on a Spectrum One FTIR spectrometer (Perkin-Bhaskar-Elmer Co., USA), the dried samples were pressed with KBr into compact pellets. The morphology of the spheres was determined by



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transmission electron microscopy (TEM, Tecnai G20, USA FEI Corp.) and field emission scanning electron microscopy (FESEM, JSM7100F, Janpan). And all dispersions were diluted with deionized water and dried on the silica wafer at room temperature before observation. A crystallinity study of the samples were performed on an X-ray diffraction (XRD, D/MAX-IIIC, Japan), taken from 5 ° to 90 ° with Cu-Kα (λ=0.154 nm) radiation to the sample at the scanning rate of 10 ° min-1. X-ray photoelectron spectroscopy (XPS) measurement was carried out on an AXIS Ultra X-ray photoelectron spectrometer (Thermo Fisher Scientific Escalab 250Xi). All binding energy was calibrated using the containment carbon (C1s 284.6 eV). The hydrodynamic size and size distribution of the samples were characterized by dynamic light scattering (DLS, Autosize Loc-Fc-963, Malvern Instrument). Thermogravimetric analysis (TGA) was performed using a Perkin–Elmer TGA-7 thermogravimetric analyzer (Waltham, Massachusetts, USA) at the heating rate of 20 °C min-1 from 30 °C to 800 °C under nitrogen atmosphere. Differential scanning calorimeter (DSC) was performed using a Perkin-Elmer DSC-7 at a heat rate of 10 °C min-1 from 80 °C to 130 °C under nitrogen atmosphere. BET surface area measurements were carried out in a gas adsorption analyzer (ASAP 2020 HD88, Micromeritics Company, US). Catalytic Activities of PSMAA/Ag nanocomposite spheres. The catalytic activities of PSMAA/Ag nanocomposite spheres were quantitatively studied by using a typical catalytic model reaction: the reduction of 4-nitrophenol to 4-aminophenol through adding catalytic material in an excess amount of NaBH4. In a typical catalytic experiment, 0.5 mL of freshly prepared NaBH4 (60 mM) aqueous solution was mixed with 2.0 mL of freshly prepared 4-nitrophenol (0.1 mM) aqueous solution in a standard quartz cuvette (path length 1 cm), and then 2 mg of PSMAA/Ag nanocomposite spheres dispersed in 0.2 mL of deionized water was added, and the mixture was monitored instantly by successive UV-vis spectra taken every 50 s in the range of 250-550 nm. To study the recyclability of PSMAA/Ag nanocomposite spheres, the used sample was separated from


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the solution after monitoring by washed with ethanol and deionized water several times for the next cycling. Similar to the above reduction process, the obtained product was redispersed in 0.2 mL of deionized water, and then mixed with 0.5 mL of NaBH4 (60 mM) aqueous solution and 2.0 mL of 4-nitrophenol aqueous solution (0.1 mM). The completion time of the reaction is strictly limited (PSMAA/Ag-1 reaction for 500 s, PSMAA/Ag-2 reaction for 350 s and PSMAA/Ag-3 reaction for 200 s). The catalytic experiment was repeated 10 times. RESULTS AND DISCUSSION Preparation process of PSMAA/Ag nanocomposite spheres. The detailed preparation process of PSMAA/Ag nanocomposite spheres has been illustrated in Figure 1. In this approach, when [Ag(NH3)2]+ aqueous solution is added into PSMAA dispersion under the atmosphere of nitrogen and stirring for 60 min at room temperature. [Ag(NH3)2]+ ions are adsorbed onto the surfaces of PSMAA spheres due to the strong electrostatic attraction between carboxyl groups (electronegative) and [Ag(NH3)2]+ ions (electropositive). And then, the mixture is kept at 70 °C and stirred for 7 h under the atmosphere of nitrogen. In the meantime, PVP is used as a proper reducing agent to reduce [Ag(NH3)2]+ ions and stabilizing agent to prevent the Ag nanoparticles from aggregation.25-26 In addition, the PSMAA/Ag nanocomposite spheres are prepared in aqueous media and without any toxic reagents are used during the preparation process. Therefore, our preparative method is environmentally friendly.

Figure 1. Schematic illustration of the formation of PSMAA/Ag nanocomposite spheres.



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FTIR spectra. The FTIR spectra of PSMAA spheres and PSMAA/Ag nanocomposite spheres have been shown in Figure 2. The absorption band at 1697 cm-1 is attributed to the carboxyl groups on the surface of the PSMAA spheres (Figure 2a-d). These functional groups play important roles in adsorbing [Ag(NH3)2]+ ions due to the strong electrostatic attraction between the carboxyl groups (electronegative) and the [Ag(NH3)2]+ ions (electropositive). The order of the peak intensity at 1697 cm-1 of PSMAA and PSMAA/Ag samples is: PSMAA/Ag-3 samples > PSMAA/Ag-2 samples > PSMAA/Ag-1 samples > PSMAA samples. This order can mainly be attributed to Ag nanoparticles make the peak intensity of carboxyl groups weaker. In addition, the typical polystyrene absorption band at 3047 cm-1, 2929 cm-1, 1600 cm-1, 1500 cm-1, 750 cm-1, 700 cm-1, and 540 cm-1 can be clearly seen in Figure 2a-d. These results confirm the formation of PSMAA and PSMAA/Ag.

Figure 2. FTIR spectra of (a) PSMAA spheres and (b) PSMAA/Ag-1 nanocomposite spheres, (c) PSMAA/Ag-2 nanocomposite spheres, (d) PSMAA/Ag-3 nanocomposite spheres.


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Figure 3. TEM images of (a) PSMAA spheres, (b) PSMAA/Ag-1 nanocomposite spheres, (c) PSMAA/Ag-2 nanocomposite spheres, (d) PSMAA/Ag-3 nanocomposite spheres and DLS distribution of (e) PSMAA spheres, (f) PSMAA/Ag-1 nanocomposite spheres, (g) PSMAA/Ag-2 nanocomposite spheres, (h) PSMAA/Ag-3 nanocomposite spheres. TEM images and DLS analysis. The TEM images of PSMAA spheres and PSMAA/Ag nanocomposite spheres have been shown in Figure 3. The size of PSMAA spheres is about 290 nm and it has smooth surface (Figure 3a). In comparison with PSMAA spheres and PSMAA/Ag nanocomposite spheres (Figure 3b-d), PSMAA/Ag nanocomposite spheres have relatively rough surfaces, and many nanoparticles can be observed on the surface of PSMAA spheres, all of which is evidence that Ag nanoparticles have been formed and loaded on the surface of PSMAA spheres. The Ag nanoparticles uniformly distribute on the surfaces of PSMAA spheres with its size ranging from 8 to 24 nm, and the averaged sizes of Ag nanoparticles are about 13.25 nm, 14.12 nm and 15.01 nm



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for samples PSMAA/Ag-1, PSMAA/Ag-2, and PSMAA/Ag-3, respectively (see the Supporting Information, Figure S1). Moreover, the TEM images of PSMAA/Ag nanocomposite spheres show that PSMAA/Ag-3 has the highest coverage degree of Ag nanoparticles, the next is PSMAA/Ag-2, and PSMAA/Ag-1 has the lowest coverage degree of Ag nanoparticles. These results indicate that the coverage degree of Ag nanoparticles on PSMAA spheres increases with the increasing of concentration of silver precursor-[Ag(NH3)2]+ ions. Table 2. Hydrodynamic diameters and PDI of PSMAA spheres and PSMAA/Ag nanocomposite spheres Sample

Dh (nm)

PDI

PSMAA

305.3

0.033

PSMAA/Ag-1

320.2

0.066

PSMAA/Ag-2

322.1

0.024

PSMAA/Ag-3

323.4

0.042

The hydrodynamic size and size distribution of the samples are characterized by DLS analysis. The polydispersity indexes (PDI) of the samples are less than 0.1 which pointing to the narrow size distribution, and the hydrodynamic diameters (Dh) is slightly larger than TEM results due to swelling effect in water35 (Figure 3e-h and Table 2). Moreover, DLS distribution also proves the adsorption of Ag nanoparticles on PSMAA spheres due to the Dh of PSMAA/Ag nanocomposite spheres is greater than the Dh of PSMAA spheres. In addition, the mean sizes of Ag nanoparticles are calculated to be 10.08 nm, 12.62 nm and 13.2 nm for samples PSMAA/Ag-1, PSMAA/Ag-2, and PSMAA/Ag-3, respectively by using the additive modification model in Dvorský et al.36 (The original values V10 and σ can be obtained from Figure S2). FESEM images. The FESEM images of PSMAA spheres and PSMAA/Ag nanocomposite spheres have been shown in Figure 4. The size of PSMAA spheres is about 290 nm and it has a


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smooth surface (Figure 4a). Ag nanoparticles are found on the surfaces of the PSMAA spheres with its size ranging from 8 to 24 nm (see the Supporting Information, Figure S1). This indicates that the Ag nanoparticles have been obtained through the reduction of [Ag(NH3)2]+ ions with PVP. Moreover, when the concentration of [Ag(NH3)2]+ ions used in reaction system is 0.3 M, only a small amount of Ag nanoparticles is deposited on the surfaces of PSMAA spheres (Figure 4b). As the concentration of [Ag(NH3)2]+ ions increases to 0.4 M, the content of Ag nanoparticles loaded on the surfaces of PSMAA spheres is slightly increased (Figure 4c). When futher increasing the concentration of [Ag(NH3)2]+ ions to 0.5 M, the content of Ag nanoparticles loaded on the surfaces of PSMAA spheres is obviously increased (Figure 4d). These results indicate that the coverage degree of Ag nanoparticles on PSMAA spheres increases with the increasing of concentration of silver precursor-[Ag(NH3)2]+ ions.

Figure 4. FESEM images of (a) PSMAA spheres, (b) PSMAA/Ag-1 nanocomposite spheres, (c) PSMAA/Ag-2 nanocomposite spheres, and (d) PSMAA/Ag-3 nanocomposite spheres. XRD patterns. The typical XRD patterns of PSMAA spheres and PSMAA/Ag nanocomposite spheres have been shown in Figure 5. The XRD patterns of PSMAA spheres indicate that PSMAA spheres are amorphous, which exhibits the broad peaks at 2θ angles of 10.6° and 19.7°. The XRD patterns of the PSMAA/Ag-1 nanocomposite spheres, PSMAA/Ag-2 nanocomposite spheres, and PSMAA/Ag-3 nanocomposite spheres are similar. On the one hand, it exhibits the broad peaks at 2θ



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angles of 10.6° and 19.7°, which relates to the broad peaks of PSMAA spheres. On the other hand, it also exhibits the sharp peaks at 2θ angles of 38.0°, 44.1°, 64.3°, 77.2°, and 81.5°, corresponding to (111), (200), (220), (311), and (222) crystal planes of Ag (JCPDS No.04−0783).37 This indicates that the Ag nanocrystallites have been obtained through the reduction of [Ag(NH3)2]+ ions with PVP. Furthermore, the diffraction peak intensity of the three PSMAA/Ag samples is different. The order of the diffraction peak intensity of the three PSMAA/Ag samples is: PSMAA/Ag samples-3 > PSMAA/Ag samples-2 > PSMAA/Ag samples-1 and this trend is in accordance with the coverage degree of Ag nanoparticles on PSMAA spheres.

Figure 5. XRD patterns of (a) PSMAA spheres and (b) PSMAA/Ag-1 nanocomposite spheres, (c) PSMAA/Ag-2 nanocomposite spheres, (d) PSMAA/Ag-3 nanocomposite spheres. XPS analysis. The chemical information of the surface of the PSMAA spheres and the PSMAA/Ag nanocomposite spheres is measured by XPS analysis. C1s and O1s signal peaks are clear in the XPS spectra of PSMAA spheres (Figure 6a). N1s signal peaks are not found in the XPS spectra of the PSMAA/Ag nanocomposite spheres (Figure 6b-d), this indicates that the PSMAA/Ag nanocomposite spheres are pure. C1s, O1s, Ag3d (Ag3d5/2, Ag3d3/2), Ag3p (Ag3p5/2, Ag3p3/2) and


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Ag3s signal peaks are clear in the XPS spectra of PSMAA/Ag nanocomposite spheres (Figure 6b-d), in which the strong Ag signal peaks at a binding energy about 370.0 eV strongly illustrate existence of the Ag element.38 Moreover, further inspection of the XPS spectra of Ag3d, we find that the XPS spectra of Ag3d exhibits two signal peaks at 368.0 eV and 374.0 eV, which is associated with the binding energy of Ag3d5/2 and Ag3d3/2, respectively, with a spin–orbit separation of 6.0 eV. Both Ag3d5/2 (368.0 eV) and Ag3d3/2 (374.0 eV) characteristic peaks are attributed to the Ag0 species, which certainly indicate the silver precursor-[Ag(NH3)2]+ ions are reduced to the metallic form by PVP.39-40 In addition, the order of the Ag signal peak intensity of the three PSMAA/Ag samples is: PSMAA/Ag samples-3 > PSMAA/Ag samples-2 > PSMAA/Ag samples-1 and this trend is in accordance with the coverage degree of Ag nanoparticles on PSMAA spheres.

Figure 6. XPS spectra of (a) PSMAA spheres, (b) PSMAA/Ag-1 nanocomposite spheres, (c) PSMAA/Ag-2 nanocomposite spheres, and (d) PSMAA/Ag-3 nanocomposite spheres.



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Figure 7. TGA curves of (a) PSMAA spheres, (b) PSMAA/Ag-1 nanocomposite spheres, (c) PSMAA/Ag-2 nanocomposite spheres, and (d) PSMAA/Ag-3 nanocomposite spheres. Thermal analysis of the PSMAA/Ag nanocomposite spheres. TGA analysis of PSMAA spheres and PSMAA/Ag nanocomposite spheres has been shown in Figure 7. For these samples, one the one hand, PSMAA/Ag-3 shows the highest 10% weight loss decomposition temperature (Td,10%) (381.7 °C), the next is PSMAA/Ag-2 (374.2 °C), and then is PSMAA/Ag-1 (359.5 °C), and the PSMAA has the lowest Td,10% (336.1 °C); On the other hand, PSMAA/Ag-3 shows the highest residue weight (Rw) (9.66 %), the next is PSMAA/Ag-2 (6.84 %), and then is PSMAA/Ag-1 (3.93 %), and the PSMAA has the lowest Rw (0 %). These results indicate that the PSMAA/Ag nanocomposite spheres show a deferred decomposition temperature and have a higher residue weight when compared to related neat PSMAA spheres. Moreover, the decomposition temperature and residue weight increase with the increasing of coverage degree of Ag nanoparticles on PSMAA spheres. This increase can be attributed to the presence of Ag nanoparticles improve the heat


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resistance of PSMAA spheres.41 Moreover, the heat resistance of PSMAA spheres increases with the increasing of coverage degree of Ag nanoparticles on PSMAA spheres.42-43

Figure 8. DSC curves of (a) PSMAA spheres, (b) PSMAA/Ag-1 nanocomposite spheres, (c) PSMAA/Ag-2 nanocomposite spheres, and (d) PSMAA/Ag-3 nanocomposite spheres. Table 3. The thermal properties of PSMAA spheres and PSMAA/Ag nanocomposite spheres Sample

Td,10% (°C)

Rw (wt %)

Tg (°C)

PSMAA

336.1

0

106.8

PSMAA/Ag-1

359.5

3.93

107.3

PSMAA/Ag-2

374.2

6.84

109.1

PSMAA/Ag-3

381.7

9.66

110.3

The glass translation temperature (Tg) of the samples is measured by DSC. For these samples, PSMAA/Ag-3 shows the highest Tg (110.3 °C), the next is PSMAA/Ag-2 (109.1 °C), then is



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PSMAA/Ag-1 (107.3 °C), and the PSMAA has the lowest Tg (106.8 °C) (Figure 8). This indicates that Tg has a elevated trend after adding Ag nanoparticles. Moreover, the Tg increases with the increasing of coverage degree of Ag nanoparticles on PSMAA spheres. The incorporation of Ag nanoparticles onto PSMAA matrix can effectively blocks the movement of chain segment, when the PSMAA chain segment movement is resisted, the Tg will be observed at a higher temperature.44-45 Hence all the PSMAA/Ag samples show improved Tg. Catalytic activities of the PSMAA/Ag nanocomposite spheres. As is known to us, 4-nitrophenol is one of the most common organic pollutants in industrial and agricultural wastewaters,46-47 but 4-aminophenol is very useful in many applications such as analgesic and antipyretic drugs, photographic development, corrosion inhibition, anticorrosion lubrication, and so on.48-49 Therefore, it will be of important significance to reduce 4-nitrophenol to 4-aminophenol with high efficiency. Though the reduction of 4-nitrophenol to 4-aminophenol by NaBH4

is

thermodynamically favorable because their standard electrode potentials is greater than zero (△E0= E0(4-nitrophenol/4-aminophenol)− E0(H3BO3/BH4)= −0.76 V− (−1.33 V) = 0.67 V), the presence of the kinetic barrier due to large potential difference between donor and acceptor molecules decreases the feasibility of this reaction.50 Ag nanocomposites are vital to catalyze the reduction of 4-nitrophenol to 4-aminophenol by NaBH4.38, 51 The mechanism of catalytic reduction of 4-nitrophenol by the PSMAA/Ag nanocomposite spheres involves the diffusion of BH4- and 4-nitrophenol from aqueous solution to the Ag nanoparticles surface, and then electron transfer from BH4- to 4-nitrophenol mediated by Ag nanoparticles on PSMAA/Ag nanocomposite spheres.52-53 Ag nanoparticles on PSMAA/Ag nanocomposite spheres can serve as electron relays from electron donor BH4- (reductant) to the acceptor 4-nitrophenolate (oxidant), overcoming the kinetic barrier and efficiently catalysing the reduction of 4-nitrophenol to 4-aminophenol. Herein, we use the reduction of 4-nitrophenol to


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4-aminophenol with an excess amount of NaBH4 as a catalytic model reaction to study quantitatively the catalytic efficiency of the prepared PSMAA/Ag nanocomposite spheres.

Figure 9. (a) UV-vis spectra of 4-nitrophenol before and after adding NaBH4. (b) Time dependent UV-vis spectra for the reduction of 4-nitrophenol by NaBH4 without catalyst. (c-e) Time dependent UV-vis spectra for the catalytic reduction of 4-nitrophenol by NaBH4 in the presence of PSMAA/Ag-1, PSMAA/Ag-2 and PSMAA/Ag-3, respectively. (f) Plots of ln (At/A0) versus reaction time for the PSMAA/Ag-1, PSMAA/Ag-2, and PSMAA/Ag-3 catalytic reduction of 4-nitrophenol.



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Figure 9a shows that the absorption peak of 4-nitrophenol at 317 nm, the absorption peak of 4-nitrophenol changes from 317 to 400 nm immediately and the color of 4-nitrophenol changes from light yellow to yellow green with the addition of NaBH4 due to the formation of 4-nitrophenolate ion. The efficiency of the catalytic reaction is studied quantitatively by monitoring the changes of the intensity of the absorption peak at 400 nm after adding the PSMAA/Ag nanocomposite spheres into the catalytic reaction system. As a control experiment, the reaction completion time of reducing 4-nitrophenol to 4-aminophenol with NaBH4 but whitout catalyst is 32 h (Figure 9b). This indicates that the efficiency of reducing 4-nitrophenol to 4-aminophenol with NaBH4 but whitout catalyst is very low. After addition of a small amount (2 mg) of catalyst, the intensity of the absorption peak at 400 nm gradually decreases with time and concomitant increase in a new peak at 295 nm corresponding to 4-aminophenol (Figure 9c-e).54-55 After the completion of reduction reaction, the peak due to nitro compound is no longer observed, which indicates that the catalytic reduction of 4-nitrophenol has proceeded successfully. Moreover, PSMAA/Ag-3 requires the shortest reaction completion time, the next is PSMAA/Ag-2, and the PSMAA-3 has the longest reaction completion time. Therefore, the order of catalytic efficiency for these PSMAA/Ag samples is PSMAA/Ag-3 > PSMAA/Ag-2 > PSMAA/Ag-1 and this trend is in accordance with the coverage degree of Ag nanoparticles on PSMAA spheres. Owing to the concentration of NaBH4 greatly exceeds the concentration of 4-nitrophenol and PSMAA/Ag, the catalytic reduction rates can be assumed to be dependent only on the concentration of 4-nitrophenol and independent of the concentration of NaBH4.56-58 Hence, the kinetic data is fitted by a first-order rate law, and the reaction rate constant (K) can be calculated by the following equation: ln (At/A0) = -Kt (where At stands for absorbance at time t and A0 for absorbance at time 0).59-60 Figure 9f shows the reaction rate constants for the three different PSMAA/Ag samples, and all the plots present a good linear relation between ln (At/A0) and time t. For the three samples,


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PSMAA/Ag-3 shows the highest K ((8.17 ± 0.22)×10-3 s-1), the next is PSMAA/Ag-2 ((4.74 ± 0.21)×10-3 s-1), and the PSMAA/Ag-1 has the lowest K ((3.19 ± 0.22)×10-3 s-1) (Table 4). This indicates that the degradation rate increases with the coverage degree of Ag nanoparticles on PSMAA spheres. Specifically, it is worth mentioning that the reaction rate constant of the PSMAA/Ag-3 found to be 8.17×10-3 s-1 is higher than values reported by Zhang (5.63×10-3 s-1), Jana (5.27×10-3 s-1) and Huang (4.73×10-4 s-1) et al.56, 61-62 In addition, specific surface area measurements provide extra supporting data to prove that the catalytic activities increase with the coverage degree of Ag nanoparticles on PSMAA spheres. Because PSMAA/Ag-3 shows the highest surface area (0.2902 m2/g), the next is PSMAA/Ag-2 (0.2352 m2/g), and the PSMAA/Ag-1 has the lowest surface area (0.1519 m2/g) (Table 5). Table 4. Summary of the catalytic activity of the three PSMAA/Ag samples towards the reduction of 4-nitrophenol to 4-aminophenol by NaBH4 Sample

Amount of sample

Time of

Reaction rate

used (mg)

completion the

constant, K (×10-3

reaction (s)

s-1)

PSMAA/Ag-1

2

500

3.19 ± 0.25

PSMAA/Ag-2

2

350

4.74 ± 0.21

PSMAA/Ag-3

2

200

8.17 ± 0.22

As a catalytic material, beside the catalytic efficiency, the recyclability of the catalytic material is the other important factor for the assessment of the catalytic material.63-65 In order to study the recyclability of these PSMAA/Ag samples, the completion time of the reaction is strictly limited (PSMAA/Ag-1 reaction for 500 s, PSMAA/Ag-2 reaction for 350 s and PSMAA/Ag-3 reaction for 200 s). These PSMAA/Ag products show similar catalytic activities only sight decrease and the conversion is still greater than 94 % after running 10 cycles (Figure 10). Therefore, the prepared



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PSMAA/Ag nanocomposite spheres have been proven to be a potential recyclable catalytic material, rendering a potential use in the fields of catalytic reduction of 4-nitrophenol to 4-aminophenol. Table 5. Specific surface area of PSMAA spheres and PSMAA/Ag nanocomposite spheres Sample

BET, surface area (m2/g)

PSMAA

0.0353

PSMAA/Ag-1

0.1519

PSMAA/Ag-2

0.2352

PSMAA/Ag-3

0.2902

Figure 10. The recyclability of PSMAA/Ag-1, PSMAA/Ag-2, and PSMAA/Ag-3 as a catalyst for the reduction of 4-nitrophenol with NaBH4.

CONCLUSIONS In summary, we present a simple, mild and green approach to prepare polystyrene-methyl acrylic acid/silver (PSMAA/Ag) nanocomposite spheres with high catalytic activities. In this way, the


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PSMAA/Ag nanocomposite spheres are prepared in aqueous media and without any toxic reagents are used during the preparation process. FTIR, TEM, FESEM, and XPS results have confirmed the formation of PSMAA spheres and PSMAA/Ag nanocomposite spheres. Moreover, the coverage degree of Ag nanoparticles on PSMAA spheres increases with the increasing of concentration of silver precursor-[Ag(NH3)2]+ ions. DLS analysis shows that the prepared PSMAA spheres and PSMAA/Ag nanocomposite spheres have narrow size distribution. XRD patterns indicate that the obtained Ag nanoparticles are crystalline. TGA results show that the prepared PSMAA/Ag nanocomposite spheres exhibit improved thermal stabilities when compared to the related neat PSMAA spheres. Moreover, the decomposition temperature and residue weight increase with the increasing of coverage degree of Ag nanoparticles on PSMAA spheres. DSC results show that the prepared PSMAA/Ag nanocomposite spheres exhibit improved glass translation temperature when compared to the related neat PSMAA spheres. Moreover, the glass translation temperature increases with the increasing of coverage degree of Ag nanoparticles on PSMAA spheres. Catalytic studies indicate that the prepared PSMAA/Ag nanocomposite spheres exhibit a high catalytic activities and good recyclability for the reduction of 4-nitrophenol, rendering a potential use in the fields of catalytic reduction of 4-nitrophenol to 4-aminophenol. ASSOCIATED CONTTENT Supporting Information The size histograms of Ag nanoparticles on these three PSMAA/Ag nanocomposite spheres; the semi-logarithmic plot of the volume distributions of original PSMAA spheres and PSMAA/Ag nanocomposite spheres by the DLS analysis of submicron fraction in aqueouus dispersion. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Authors



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*

E-mail: [email protected]. Tel.: +852 34427724. fax: +852 34420542.

Notes The authors declare no competing financial interest ACKNOWLEDGEMENTS This research work was financially supported by the Transformation of High and New Technological Achievements and Professional Project of Wuhan (2014010303010159). Authors also acknowledge the Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials for providing necessary facilities. REFERENCES (1) Zaera, F. Nanostructured Materials for Applications in Heterogeneous Catalysis. Chem. Soc. Rev. 2013, 42, 2746-2762. (2) Gobre, V. V.; Tkatchenko, A. Scaling Laws for Van Der Waals Interactions in Nanostructured Materials. Nat Commun. 2013, 4, 2341-2341. (3) Shen, L.; Li, H.; Uchaker, E.; Zhang, X.; Cao, G. General Strategy for Designing Core-Shell Nanostructured Materials for High-Power Lithium Ion Batteries. Nano Lett. 2012, 12, 5673-5678. (4) Sanli, D.; Bozbag, S. E.; Erkey, C. Synthesis of Nanostructured Materials Using Supercritical CO2: Part I. Physical Transformations. J. Mater. Sci. 2011, 47, 2995-3025. (5) Wu, M.; Chang, H. Self-Assembly of NiO-Coated ZnO Nanorod Electrodes with Core–Shell Nanostructures as Anode Materials for Rechargeable Lithium-Ion Batteries. J. Phys. Chem. C 2013, 117, 2590-2599. (6) Li, X.; Robinson, S. M.; Gupta, A.; Saha, K.; Jiang, Z.; Moyano, D. F.; Sahar, A.; Riley, M. A.; Rotello, V. M. Functional Gold Nanoparticles as Potent Antimicrobial Agents against Multi-Drug-Resistant Bacteria. ACS nano 2014, 8, 10682-10686. (7) Zhao, Y.; Tian, Y.; Cui, Y.; Liu, W.; Ma, W.; Jiang, X. Small Molecule-Capped Gold Nanoparticles as Potent Antibacterial Agents that Target Gram-Negative Bacteria. J. Am. Chem. Soc. 2010, 132, 12349-12356. (8) Zhu, H.; Shang, Y.; Wang, W.; Zhou, Y.; Li, P.; Yan, K.; Wu, S.; Yeung, K. W.; Xu, Z.; Xu, H.; et al. Fluorescent Magnetic Fe3O4/Rare Earth Colloidal Nanoparticles for Dual-Modality Imaging. Small 2013, 9, 2991-3000.


Page 22 of 28

Page 23 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(9) Yu, J.; Low, J.; Xiao, W.; Zhou, P.; Jaroniec, M. Enhanced Photocatalytic CO(2)-Reduction Activity of Anatase TiO(2) by Coexposed {001} and {101} Facets. J. Am. Chem. Soc. 2014, 136, 8839-8842. (10) Herves, P.; Perez-Lorenzo, M.; Liz-Marzan, L. M.; Dzubiella, J.; Lu, Y.; Ballauff, M. Catalysis by Metallic Nanoparticles in Aqueous Solution: Model Reactions. Chem. Soc. Rev. 2012, 41, 5577-5587. (11) Choi, H.; Lee, J. P.; Ko, S. J.; Jung, J. W.; Park, H.; Yoo, S.; Park, O.; Jeong, J. R.; Park, S.; Kim, J. Y. Multipositional Silica-Coated Silver Nanoparticles for High-Performance Polymer Solar Cells. Nano Lett. 2013, 13, 2204-2208. (12) Walters, G.; Parkin, I. P. The Incorporation of Noble Metal Nanoparticles into Host Matrix Thin Films: Synthesis, Characterisation and Applications. J. Mater. Chem. 2009, 19, 574-590. (13) Nassar, M. A.; Youssef, A. M. Mechanical and Antibacterial Properties of Recycled Carton Paper Coated by PS/Ag Nanocomposites for Packaging. Carbohydr. Polym. 2012, 89, 269-274. (14) Liu, C.; Yang, D.; Jiao, Y.; Tian, Y.; Wang, Y.; Jiang, Z. Biomimetic Synthesis of TiO(2)-SiO(2)-Ag Nanocomposites with Enhanced Visible-Light Photocatalytic Activity. ACS Appl. Mater. Interfaces 2013, 5, 3824-3832. (15) Zhang, X.; Li, M.; He, X.; Hang, R.; Huang, X.; Wang, Y.; Yao, X.; Tang, B. Antibacterial Activity of Single Crystalline Silver-Doped Anatase TiO2 Nanowire Arrays. Appl. Surf. Sci. 2016, 372, 139-144. (16) Lin, A. Y.; Young, J. K.; Nixon, A. V.; Drezek, R. A. Encapsulated Fe3O4/Ag Complexed Cores in Hollow Gold Nanoshells for Enhanced Theranostic Magnetic Resonance Imaging and Photothermal Therapy. Small 2014, 10, 3246-3251. (17) Li, Q.; Tian, M.; Liu, L.; Zou, H.; Zhang, L.; Wang, W. C. Facile Preparation of α-Fe2O3@Ag Core–Shell Structured Nanoparticles. Electrochim. Acta 2013, 91, 114-121. (18) Shi, L.; Wang, A.; Zhang, T.; Zhang, B.; Su, D.; Li, H.; Song, Y. One-Step Synthesis of Au–Pd Alloy Nanodendrites and Their Catalytic Activity. J. Phys. Chem. C 2013, 117, 12526-12536. (19) Wang, M.; Fu, J.; Huang, D.; Zhang, C.; Xu, Q. Silver Nanoparticles-Decorated Polyphosphazene Nanotubes: Synthesis and Applications. Nanoscale 2013, 5, 7913-7919. (20) Bastús, N. G.; Merkoçi, F.; Piella, J.; Puntes, V. Synthesis of Highly Monodisperse Citrate-Stabilized Silver Nanoparticles of up to 200 nm: Kinetic Control and Catalytic Properties. Chem. Mater. 2014, 26, 2836-2846. (21) Chi, Y.; Tu, J.; Wang, M.; Li, X.; Zhao, Z. One-Pot Synthesis of Ordered Mesoporous Silver Nanoparticle/Carbon Composites for Catalytic Reduction of 4-Nitrophenol. J. Colloid Interface Sci. 2014, 423, 54-59.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(22) Wang, K.; Zhang, X.; Niu, C.; Wang, Y. Template-Activated Strategy toward One-Step Coating Silica Colloidal Microspheres with Sliver. ACS Appl. Mater. Interfaces 2014, 6, 1272-1278. (23) Shin, Y.; Bae, I.; Arey, B. W.; Exarhos, G. J. Simple Preparation and Stabilization of Nickel Nanocrystals on Cellulose Nanocrystal. Mater. Lett. 2007, 61, 3215-3217. (24) Cong, Y.; Xia, T.; Zou, M.; Li, Z.; Peng, B.; Guo, D.; Deng, Z. Mussel-Inspired Polydopamine Coating as a Versatile Platform for Synthesizing Polystyrene/Ag Nanocomposite Particles with Enhanced Antibacterial Activities. J. Mater. Chem. B 2014, 2, 3450. (25) Deng, Z.; Chen, M.; Wu, L. Novel Method to Fabricate SiO2/Ag Composite Spheres and Their Catalytic, Surface-Enhanced Raman Scattering Properties. J. Phys. Chem. C 2007, 111, 11692-11698. (26) Deng, Z.; Zhu, H.; Peng, B.; Chen, H.; Sun, Y.; Gang, X.; Jin, P.; Wang, J. Synthesis of PS/Ag Nanocomposite Spheres with Catalytic and Antibacterial Activities. ACS Appl. Mater. Interfaces 2012, 4, 5625-5632. (27) Zhang, Y.; Liu, S.; Wang, L.; Qin, X.; Tian, J.; Lu, W.; Chang, G.; Sun, X. One-Pot Green Synthesis of Ag Nanoparticles-Graphene Nanocomposites and Their Applications in SERS, H2O2, and Glucose Sensing. RSC Adv. 2012, 2, 538-545. (28) Zhao, K.; Zhao, J.; Wu, C.; Zhang, S.; Deng, Z.; Hu, X.; Chen, M.; Peng, B. Fabrication of Silver-Decorated Sulfonated Polystyrene Microspheres for Surface-Enhanced Raman Scattering and Antibacterial Applications. RSC Adv. 2015, 5, 69543-69554. (29) Zhao, K.; Wu, C.; Deng, Z.; Guo, Y.; Peng, B. Preparation of Silver Decorated Silica Nanocomposite Rods for Catalytic and Surface-Enhanced Raman Scattering Applications. RSC Adv. 2015, 5, 52726-52736. (30) Lucky, S. S.; Soo, K. C.; Zhang, Y. Nanoparticles in Photodynamic Therapy. Chem. Rev. 2015, 115, 1990-2042. (31) Jung, S. M.; Jung, H. Y.; Fang, W.; Dresselhaus, M. S.; Kong, J. A Facile Methodology for the Production of in Situ Inorganic Nanowire Hydrogels/Aerogels. Nano Lett. 2014, 14, 1810-1817. (32) Liu, C.; Ge, C.; Wang, A.; Yin, H.; Ren, M.; Zhang, Y.; Yu, L.; Jiang, T. Synthesis of Porous Hollow Silica Spheres Using Functionalized Polystyrene Latex Spheres as Templates. Korean J. Chem. Eng. 2011, 28, 1458-1463. (33) Zhou, J.; Wang, J.; Huang, Y.; Liu, G.; Wang, L.; Chen, S.; Li, X.; Wang, D.; Song, Y.; Jiang, L. Large-area Crack-Free Single-Crystal Photonic Crystals via Combined Effects of Polymerization-Assisted Assembly and Flexible Substrate. NPG Asia Mater. 2012, 4, 1-7. (34) Ge, C.; Zhang, D.; Wang, A.; Yin, H.; Ren, M.; Liu, Y.; Jiang, T.; Yu, L. Synthesis of Porous Hollow Silica Spheres Using Polystyrene–Methyl Acrylic Acid Latex Template at Different Temperatures. J. Phys. Chem. Solids 2009, 70, 1432-1437.


Page 24 of 28

Page 25 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(35) Kallumadil, M.; Tada, M.; Nakagawa, T.; Abe, M.; Southern, P.; Pankhurst, Q. A. Suitability of Commercial Colloids for Magnetic Hyperthermia. J. Magn. Magn. Mater. 2009, 321, 1509-1513. (36) Dvorský, R.; Trojková, J.; Praus, P.; Luňáček, J. Analysis of Mechanisms of Composite Particles Modification in Liquid Dispersions. Mater. Res. Bull. 2013, 48, 2286-2288. (37) Xu, Y.; Xu, H.; Yan, J.; Li, H.; Huang, L.; Zhang, Q.; Huang, C.; Wan, H. A Novel Visible-Light-Response Plasmonic Photocatalyst CNT/Ag/AgBr and Its Photocatalytic Properties. Phys. Chem. Chem. Phys. 2013, 15, 5821-5830. (38) Qu, Z.; Bu, Y.; Qin, Y.; Wang, Y.; Fu, Q., The Improved Reactivity of Manganese Catalysts by Ag in Catalytic Oxidation of Toluene. Appl. Catal. B-Environ. 2013, 132-133, 353-362. (39) Li, Y.; Fang, L.; Jin, R.; Yang, Y.; Fang, X.; Xing, Y.; Song, S. Preparation and Enhanced Visible Light Photocatalytic Activity of Novel g-C3N4 Nanosheets Loaded with Ag2CO3 Nanoparticles. Nanoscale 2015, 7, 758-764. (40) Li, S.; Shen, Y.; Xie, A.; Yu, X.; Qiu, L.; Zhang, L.; Zhang, Q. Green Synthesis of Silver Nanoparticles Using Capsicum Annuum L. Extract. Green Chem. 2007, 9, 852-858. (41) Yougen, H.; Tao, Z.; Pengli, Z.; Rong, S. Preparation of Monodisperse Polystyrene/Silver Composite Microspheres and Their Catalytic Properties. Colloid Polym. Sci. 2011, 290, 401-409. (42) Ma, Y.; Zhang, Q. Preparation and Characterization of Monodispersed PS/Ag Composite Microspheres through Modified Electroless Plating. Appl. Surf. Sci. 2012, 258, 7774-7780. (43) Vukoje, I. D.; Vodnik, V. V.; Džunuzović, J. V.; Džunuzović, E. S.; Marinović-Cincović, M. T.; Jeremić, K.; Nedeljković, J. M. Characterization of Silver/Polystyrene Nanocomposites Prepared by in Situ Bulk Radical Polymerization. Mater. Res. Bull. 2014, 49, 434-439. (44) Gu, S.; Liu, L.; Yan, B. Effects of Ionic Solvent-Free Carbon Nanotube Nanofluid on the Properties of Polyurethane Thermoplastic Elastomer. J. Polym. Res. 2014, 21, 1-10. (45) Zhang, Y.; Shen, J.; Li, Q.; Pang, L.; Xu, Z.; Yeung, K. W. K.; Yi, C. Effect of the Adding of Rod-Like Attapulgite upon the Properties of Polyimides Produced by Random Copolycondensation. J. Mater. Sci. 2013, 48, 4973-4982. (46) Wang, M.; Jiang, T.; Lu, Y.; Liu, H. J.; Chen, Y. Gold Nanoparticles Immobilized in Hyperbranched Polyethylenimine Modified Polyacrylonitrile Fiber as Highly Efficient and Recyclable Heterogeneous Catalysts for the Reduction of 4-Nitrophenol. J. Mater. Chem. A 2013, 1, 5923-5933. (47) Li, S.; Guo, S.; Yang, H.; Gou, G.; Ren, R.; Li, J.; Dong, Z.; Jin, J.; Ma, J. Enhancing Catalytic Performance of Au Catalysts by Noncovalent Functionalized Graphene Using Functional Ionic Liquids. J Hazard. Mater. 2014, 270, 11-17.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(48) Zheng, J.; Dong, Y.; Wang, W.; Ma, Y.; Hu, J.; Chen, X. In Situ Loading of Gold Nanoparticles on Fe3O4@SiO2 Magnetic Nanocomposites and Their High Catalytic Activity. Nanoscale 2013, 5, 4894-4901. (49) Cheng, T.; Zhang, D.; Li, H.; Liu, G. Magnetically Recoverable Nanoparticles as Efficient Catalysts for Organic Transformations in Aqueous Medium. Green Chem. 2014, 16, 3401-3427. (50) Gangula, A.; Podila, R.; Ramakrishna, M.; Karanam, L.; Janardhana, C.; Rao, A. M. Catalytic Reduction of 4-Nitrophenol Using Biogenic Gold and Silver Nanoparticles Derived from Breynia Rhamnoides. Langmuir 2011, 27, 15268-15274. (51) Wunder, S.; Polzer, F.; Lu, Y.; Mei, Y.; Ballauff, M. Kinetic Analysis of Catalytic Reduction of 4-Nitrophenol by Metallic Nanoparticles Immobilized in Spherical Polyelectrolyte Brushes. J. Phys. Chem. C 2010, 114, 8814-8820. (52) Ai, L.; Yue, H.; Jiang, J. Environmentally Friendly Light-Driven Synthesis of Ag Nanoparticles in Situ Grown on Magnetically Separable Biohydrogels as Highly Active and Recyclable Catalysts for 4-Nitrophenol Reduction. J. Mater. Chem. C 2012, 22, 23447-23453. (53) Ansari, S. A.; Khan, M. M.; Ansari, M. O.; Lee, J.; Cho, M. H. Biogenic Synthesis, Photocatalytic, and Photoelectrochemical Performance of Ag–ZnO Nanocomposite. J.Phys.Chem. C 2013, 117, 27023-27030. (54) Gao, S.; Jia, X.; Li, Z.; Chen, Y. Hierarchical Plasmonic-Metal/Semiconductor Micro/Nanostructures: Green Synthesis and Application in Catalytic Reduction of p-Nitrophenol. J Nanopart. Res. 2012, 14, 486-494. (55) Yao, T.; Zuo, Q.; Wang, H.; Wu, J.; Xin, B.; Cui, F.; Cui, T. A Simple Way to Prepare Pd/Fe(3)O(4)/Polypyrrole Hollow Capsules and Their Applications in Catalysis. J. Colloid Interface Sci. 2015, 450, 366-373. (56) Zhang, W.; Tan, F.; Wang, W.; Qiu, X.; Qiao, X.; Chen, J. Facile, Template-Free Synthesis of Silver Nanodendrites with High Catalytic Activity for the Reduction of p-Nitrophenol. J. Hazard. Mater. 2012, 217-218, 36-42. (57) Venkatesham, M.; Ayodhya, D.; Madhusudhan, A.; Veera Babu, N.; Veerabhadram, G. A Novel Green One-Step Synthesis of Silver Nanoparticles Using Chitosan: Catalytic Activity and Antimicrobial Studies. Appl. Nanosci. 2012, 4, 113-119. (58) Dash, S. S.; Majumdar, R.; Sikder, A. K.; Bag, B. G.; Patra, B. K. Saraca Indica Bark Extract Mediated Green Synthesis of Polyshaped Gold Nanoparticles and Its Application in Catalytic Reduction. Appl. Nanosci. 2013, 4, 485-490. (59) Rashid, M. H.; Mandal, T. K. Templateless Synthesis of Polygonal Gold Nanoparticles: An Unsupported and Reusable Catalyst with Superior Activity. Adv. Funct. Mater. 2008, 18, 2261-2271.


Page 26 of 28

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(60) Lam, E.; Hrapovic, S.; Majid, E.; Chong, J. H.; Luong, J. H. Catalysis Using Gold Nanoparticles Decorated on Nanocrystalline Cellulose. Nanoscale 2012, 4, 997-1002. (61) Jana, S.; Ghosh, S.; Nath, S.; Pande, S.; Praharaj, S.; Panigrahi, S.; Basu, S.; Endo, T.; Pal, T. Synthesis of Silver Nanoshell-Coated Cationic Polystyrene Beads: A Solid Phase Catalyst for the Reduction of 4-Nitrophenol. Appl. Catal. A-Gen. 2006, 313, 41-48. (62) Huang, X.; Xiao, Y.; Zhang, W.; Lang, M. In-Situ Formation of Silver Nanoparticles Stabilized by Amphiphilic Star-Shaped Copolymer and Their Catalytic Application. Appl. Surf. Sci. 2012, 258, 2655-2660. (63) Dhakshinamoorthy, A.; Garcia, H. Metal-Organic Frameworks as Solid Catalysts for the Synthesis of Nitrogen-Containing Heterocycles. Chem. Soc. Rev. 2014, 43, 5750-5765. (64) Kainz, Q. M.; Linhardt, R.; Grass, R. N.; Vilé, G.; Pérez-Ramírez, J.; Stark, W. J.; Reiser, O. Palladium Nanoparticles Supported on Magnetic Carbon-Coated Cobalt Nanobeads: Highly Active and Recyclable Catalysts for Alkene Hydrogenation. Adv. Funct. Mater. 2014, 24, 2020-2027. (65) Sheldon, R. A. Fundamentals of Green Chemistry: Efficiency in Reaction Design. Chem. Soc. Rev. 2012, 41, 1437-1451.



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