Dalton Transactions View Article Online

Published on 14 October 2013. Downloaded by University of Hong Kong Libraries on 19/10/2014 10:11:06.

PAPER

Cite this: Dalton Trans., 2014, 43, 982

View Journal | View Issue

Fullerene modified C3N4 composites with enhanced photocatalytic activity under visible light irradiation Bo Chai,* Xiang Liao, Fakun Song and Huan Zhou Fullerene modified C3N4 (C60/C3N4) composites with efficient photocatalytic activity under visible light irradiation were fabricated by a simple adsorption approach. The as-prepared C60/C3N4 composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance absorption spectra (DRS), Fourier transform infrared spectroscopy (FTIR) and photoluminescence

Received 6th September 2013, Accepted 14th October 2013 DOI: 10.1039/c3dt52454j www.rsc.org/dalton

1.

spectra (PL). The photocatalytic degradation of rhodamine B (RhB) by the C60/C3N4 composites was investigated and optimized, suggesting that the optimal amount of C60 in the composites was 1 wt%. The significantly enhanced photocatalytic activity could be attributed to the efficient separation of photogenerated electrons and holes in the C60/C3N4 composites. A possible mechanism of C60/C3N4 composites as photocatalysts was proposed.

Introduction

Semiconductor photocatalytic technology has attracted considerable attention due to its great potential in solving current environment and energy problems with abundant solar light.1–3 To date, various kinds of semiconductor photocatalysts including metal oxides, sulfides and halides have been explored.4–10 However, the development of efficient, sustainable, visible-light-driven photocatalysts remains a significant challenge. Recently, a polymeric semiconductor, graphite-like carbon nitride (C3N4), has been reported to be a metal-free and visible light active photocatalyst for the photodegradation of organic pollutants and water splitting for hydrogen production under visible light irradiation.11–15 C3N4 possesses a very high thermal and chemical stability due to the strong covalent bonds between carbon and nitride atoms as well as unique electronic and optical properties, indicating that C3N4 has a promising potential in the photocatalysis field. Nevertheless, the photocatalytic efficiency of bare C3N4 is limited, owing to the high recombination rate of photogenerated electron–hole pairs. To resolve this problem, many methods have been proposed to enhance the photocatalytic activity of C3N4, such as by fabricating mesoporous structures,16,17 exfoliating C3N4 nanosheets,18 doping with metal or nonmetal elements,19–21 and coupling with other semiconductors.22–28

School of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430023, P. R. China. E-mail: [email protected]; Fax: +86-27-83943956; Tel: +86-27-83943956

982 | Dalton Trans., 2014, 43, 982–989

In recent years, the use of carbonaceous materials such as activated carbon (AC),29,30 carbon nanotubes (CNTs)31–33 and graphene (GE)34 for the enhancement of photocatalytic performances of semiconductors has attracted considerable attention because of their special structures and unique electronic properties. Some research groups have developed these novel heterojunction photocatalysts by combination of C3N4 with carbonaceous materials.35–38 Yu et al. have prepared the graphene/C3N4 composites by the impregnation–chemical reduction strategy. The resulting composites showed high visible light photocatalytic activity for hydrogen production.35 Quan et al. have fabricated the graphene oxide modified C3N4 (GO/C3N4) by a sonochemical approach. The photocatalytic degradation rate constants of rhodamine B (RhB) and 2,4dichlorophenol with GO/C3N4 under visible light irradiation were 3.80 and 2.08 times as large as that with pristine C3N4.36 Li et al. have synthesized CNTs modified C3N4 (CNTs/C3N4) composites via a hydrothermal method. The as-prepared CNTs/C3N4 displayed higher photocatalytic activity for degradation of methylene blue (MB) than that of single C3N4.37 Ge et al. have prepared multi-wall carbon nanotubes/C3N4 (MWNTs/C3N4) composites via a facile heating method. The MWNTs/C3N4 showed an improved photocatalytic hydrogen production rate under visible light irradiation.38 The aforementioned results suggest that the C3N4 coupled with carbonaceous materials would greatly enhance its photocatalytic activity. Fullerenes (C60) represent another allotrope of carbon with unique electronic properties. C60 is a closed-shell configuration consisting of 30 bonding molecular orbitals with 60 π-electrons, which is favorable for efficient electron transfer

This journal is © The Royal Society of Chemistry 2014

View Article Online

Published on 14 October 2013. Downloaded by University of Hong Kong Libraries on 19/10/2014 10:11:06.

Dalton Transactions

reduction.39 The unique structure of C60 can act as an excellent electron acceptor, which efficiently causes a rapid photoinduced charge separation and a relatively slow charge recombination.40 C60 has been coupled with ZnO,39 TiO2,40,41 Bi2WO6,42 and Bi2MoO6,43 and the resulting photocatalytic activity is indeed improved to a certain degree. However, to the best of our knowledge, there is no reported investigation focused on the photocatalytic activity of C60/C3N4 composites. Herein, the C60/C3N4 composites were prepared by physically adsorbing C60 on the surface of C3N4 and applied to photocatalytic degradation of RhB solution under visible light irradiation. A conspicuously enhanced photocatalytic activity compared with single C3N4 was achieved in the present study. Moreover, the effect of mass ratios of the C60/C3N4 composites on photocatalytic activity was explored comparatively. The possible mechanism of the enhanced photocatalytic activity was proposed based on the obtained experimental results.

2. Experimental 2.1

Material preparation

Graphite-like carbon nitrides (C3N4) were synthesized by thermal treatment of 5 g urea (AR, Sinopharm Chemical Reagent Co. Ltd, China) in an alumina crucible with a cover. After drying at 80 °C for 12 h, the urea was heated at 500 °C for 3 h at a heating rate of 5 °C min−1. The resulting yellow powder was collected for use without any further treatment. C60/C3N4 composites were prepared as follows: an appropriate amount of C60 ( purity > 99.9%, Shanghai Aladdin Reagent Co. Ltd, China) was added to 50 mL toluene and sonicated for 1 h to make C60 disperse totally. The as-prepared C3N4 powder (0.5 g) was added to the above solution and stirred for 6 h at room temperature. After volatilization of the toluene, the resulting powder was washed with ethanol and distilled water for several times, and dried under vacuum at 80 °C for 12 h to obtain the C60 hybridized C3N4 samples. The C60/C3N4 composites with different mass ratios from 0.5 to 2 wt% were prepared by following the same procedure as above. 2.2

Material characterization

The products were characterized by XRD patterns using a Bruker D8 Advance X-ray diffractometer with Cu-Kα irradiation (λ = 0.154178 nm) at 40 kV and 40 mA. The morphology of the samples was investigated using a JEOL JSM-6700F operating at 10 kV. The HRTEM measurement was conducted using a JEOL JEM 2100F microscope working at 200 kV. The XPS measurement was performed using a VG Multilab 2000 with an Al-Kα source operating at 300 W. UV-vis diffuse reflectance absorption spectra were recorded on a Shimadzu UV-3600 spectrophotometer equipped with an integrating sphere using BaSO4 as the reference sample. The FTIR spectra of the samples were recorded on a Thermo Nicolet Avatar 360 spectrometer using conventional KBr pellets. PL was measured at room temperature on a Varian Cary Eclipse fluorescence spectrophotometer with an excitation wavelength of 340 nm.

This journal is © The Royal Society of Chemistry 2014

Paper

2.3

Photocatalytic activity measurement

The photocatalytic activities of C60/C3N4 composites were evaluated by degradation of RhB aqueous solution under visible light irradiation. 30 mg of photocatalysts were added into 50 mL of RhB solution with the initial concentration of 1.0 × 10−5 mol L−1. A 500 W xenon lamp (Changzhou Yuyu Electro-Optical Device Co. Ltd, China) with a 420 nm cutoff filter provided visible light irradiation. Prior to irradiation, the suspensions were magnetically stirred in the dark for 30 min to ensure the establishment of an adsorption–desorption equilibrium. At given irradiation time intervals, 4 mL of the suspensions were collected and then the slurry samples including the photocatalysts and RhB solution were centrifuged (12 000 rpm, 10 min) to remove the photocatalysts. The TU-1810 spectrometer was used to measure the concentration changes of RhB solution.

3. Results and discussion 3.1

XRD analysis

The XRD patterns of C60, C3N4 and 1 wt% C60/C3N4 composite are shown in Fig. 1. As could be seen from the diffraction pattern of C3N4, there are two peaks at about 13.1 and 27.6°, which are characteristic peaks of graphite-like C3N4 corresponding to the (100) and (002) planes.13,14 C60 exhibits diffraction peaks of the (111), (220), (311) and (222) planes at 2θ = 10.7°, 17.7°, 20.7° and 21.7°, which could be indexed to a cubic phase of C60 (JCPDS no. 44-558).40 As for 1 wt% C60/C3N4 composite, the diffraction peak position and shape hardly change compared with those of bare C3N4, indicating that adding C60 does not influence the lattice structure of C3N4. No diffraction peaks corresponding to C60 are observed in the 1 wt% C60/C3N4 composite, which may be due to the small amount of C60 and high dispersion in the sample. 3.2

Microstructure analysis

The representative SEM and TEM images of bare C3N4 and 1 wt% C60/C3N4 composite are shown in Fig. 2. As could be seen from Fig. 2a, C3N4 shows an obvious two-dimensional

Fig. 1

XRD patterns of bare C3N4, C60 and 1 wt% C60/C3N4 composite.

Dalton Trans., 2014, 43, 982–989 | 983

View Article Online

Paper

Dalton Transactions

Published on 14 October 2013. Downloaded by University of Hong Kong Libraries on 19/10/2014 10:11:06.

(2D) lamellar structure with a layer thickness of about 10–20 nm, which is consistent with the previous report.13,14 The 1 wt% C60/C3N4 (Fig. 2b) composite also presents the flaky structure similar to bare C3N4, suggesting that the introduction of C60 has no effect on the morphology of C3N4. In Fig. 2c, the TEM image of C60/C3N4 composite also displays 2D lamellar structure, which is in good agreement with the SEM observation. Moreover, there are many mesopores existing in those lamellar structures, which may be due to a large number of gases such as NH3 and CO2 released during the thermal treatment of urea, leading to porous structures in the flakes of the obtained C3N4.44 Fig. 2d depicts the corresponding HRTEM image of 1 wt% C60/C3N4 composite. The center region presents an amorphous structure, which could be assigned to graphite-like C3N4. It is observed that there are some indistinct and incomplete lattice fringes in the outer boundary, which may be C60 molecules. Accordingly, it could be estimated that C60 is highly dispersed on the surface of C3N4. 3.3

XPS analysis

The XPS measurement was performed to determine the chemical composition and valence state of various species. The peak positions in all of the XPS spectra are calibrated with C 1s at 284.6 eV. Fig. 3a displays the XPS survey spectra of C3N4 and 1 wt% C60/C3N4 composite. The C 1s (Fig. 3b) high resolution XPS spectra have two distinct peaks at 284.6 and 288.0 eV. The peak at 288.0 eV is identified as sp2-bonded carbon (N–CvN).13 The peak located at 284.6 eV could be assigned to adventitious carbon, C–C bond from the C60 and graphitic carbon. As could been seen, there is no obvious difference in C 1s XPS spectra before and after hybridizing C60 into C3N4, which may be ascribed to the fact that a small amount of C60 does not change the C 1s peak evidently. Besides, the XPS peaks for C60 are concealed by that of C3N4; a similar result has been reported in CNTs/C3N4 composites.37 In Fig. 3c, the high resolution XPS spectra of N 1s could be fitted with three peaks. The N 1s peaks at 398.3 eV and 399.1 eV correspond to sp2 hybridized aromatic N bonded to carbon atoms (CvN–C) and the tertiary N bonded to carbon atoms in the form of N–(C)3 or H–N–(C)2, while the weaker peak at 400.3 eV could be ascribed to N–H side groups, which are consistent with the reported results on N 1s XPS spectra.13,44 3.4

Fig. 2 SEM and TEM images of bare C3N4 and 1 wt% C60/C3N4 composite: (a) bare C3N4; (b–d) 1 wt% C60/C3N4 composite.

984 | Dalton Trans., 2014, 43, 982–989

UV-vis diffuse reflectance absorption spectra

Fig. 4 shows the UV-vis diffuse reflectance absorption spectra of single C3N4 and 1 wt% C60/C3N4 composite. As could be seen, C3N4 and the C60/C3N4 composite present a sharp absorption edge at about 435 nm, which are assigned to the intrinsic band gap absorption of C3N4.24 The band gap of C3N4 is estimated to be 2.85 eV according to the equation Eg = 1240/λg, where Eg is the band gap energy of the semiconductor; and λg is the optical absorption edge of the semiconductor. Compared with C3N4, the 1 wt% C60/C3N4 composite shows more intensive absorption over the whole visible light region consistent with the gray color of the sample.

This journal is © The Royal Society of Chemistry 2014

View Article Online

Published on 14 October 2013. Downloaded by University of Hong Kong Libraries on 19/10/2014 10:11:06.

Dalton Transactions

Paper

Fig. 4 UV-vis diffuse reflectance absorption spectra of bare C3N4 and 1 wt% C60/C3N4 composite.

Fig. 5

Fig. 3 XPS spectra of C3N4 and 1 wt% C60/C3N4 composite: (a) XPS survey specta; (b) high resolution C 1s specta; (c) high resolution N 1s specta.

3.5

FTIR analysis

Fig. 5 shows the FTIR spectra of bare C3N4, C60 and 1 wt% C60/C3N4 composite. The bare C3N4 shows FTIR features similar to that in the previous results.11–15 The absorption band at 1635 cm−1 could be ascribed to CvN stretching vibration modes, while the four strong peaks at 1253, 1328, 1420 and 1574 cm−1 are assigned to aromatic C–N stretching. The sharp peak at 812 cm−1 is related to the s-triazine ring system.22 A shoulder band near 3168 cm−1 corresponds to the stretching modes of terminal N–H groups at the defect sites of the aromatic ring.24 The peaks at 528, 575, 1180 and 1427 cm−1 are attributed to the internal modes of the C60 molecule.40 For the 1 wt% C60/C3N4 composite, only the

This journal is © The Royal Society of Chemistry 2014

FTIR spectra of bare C3N4, C60 and 1 wt% C60/C3N4 composite.

characteristic peaks of C3N4 appear in the spectrum because of the low quantity of C60 in the composite.36 However, the peak at 1253 cm−1 in C3N4 shows a little shift to the lower wavenumber of 1245 cm−1 in the C60/C3N4 composite. The red shift of the peak indicates that the bond strength of C–N is weakened, suggesting that the conjugated system of C3N4 is stretched and the interaction between the C3N4 and C60 has already appeared.37 The interaction between the C3N4 and C60 may benefit the electron transfer, and then enhance the photocatalytic activity of composite materials. 3.6

Photocatalytic activity

Fig. 6 displays the photocatalytic activities of bare C3N4 and C60/C3N4 composites with different mass ratios for the degradation of RhB solution. For comparison, the blank test was also conducted under the same reaction conditions. It could be seen that the degradation percentage of RhB is very low in the absence of photocatalysts under visible light irradiation for 60 min. Bare C3N4 exhibits weak photocatalytic activity with a degradation percentage of 54%. The C60/C3N4 composites greatly enhance the photocatalytic activities. After 60 min visible light irradiation, the photocatalytic degradation percentages of RhB are about 87%, 97% and 84% for 0.5 wt%, 1 wt% and 2 wt% C60/C3N4 composites, respectively. With enhancing

Dalton Trans., 2014, 43, 982–989 | 985

View Article Online

Published on 14 October 2013. Downloaded by University of Hong Kong Libraries on 19/10/2014 10:11:06.

Paper

Dalton Transactions

Fig. 6 Comparison of photocatalytic activities of the samples for the degradation of RhB solution at ambient temperature; C and C0 denote the reaction and absorption equilibrium concentrations of RhB in the system, respectively.

Fig. 8 Stability study of photocatalytic degradation of RhB by 1 wt% C60/C3N4 composite under visible light irradiation.

the C60 contents, the photocatalytic activity of composites increases and the 1 wt% C60/C3N4 composite shows the highest photocatalytic performance. While further increasing the C60 amount, the photocatalytic performance decreases. Hence, the optimal amount of C60 in the composites was 1 wt%. Generally, the photocatalytic degradation of RhB could be considered as a pseudo-first-order reaction with low concentration, and its kinetics could be expressed as follows: lnðC=C0 Þ ¼ kt

ð1Þ

where k is the degradation rate constant, C0 and C are the absorption equilibrium concentration of RhB and the concentration of the pollution at a reaction time of t, respectively.45 As shown in Fig. 7, the rate constants (k) of different samples are 0.00998, 0.03349, 0.05818, 0.03308 and 0.00041 min−1 for bare C3N4, 0.5 wt%, 1 wt%, 2 wt% C60/C3N4 composites and without catalysts, respectively. The stability of a photocatalyst is important for its assessment and application. The recycling runs for the photocatalytic degradation of RhB over 1 wt% C60/C3N4 composite

Fig. 7 Pseudo-first-order kinetics curves of RhB degradation over different samples.

986 | Dalton Trans., 2014, 43, 982–989

Fig. 9 XRD patterns of 1 wt% C60/C3N4 composite before and after the recycling photocatalytic experiments.

were performed to evaluate its photocatalytic stability. After every 60 min of photodegradation, the separated photocatalysts were washed with distilled water and dried. As shown in Fig. 8, the high photocatalytic degradation efficiency of RhB could be maintained after five recycling runs and there is no obvious deactivation. The results confirm that the C60/C3N4 composite is not photo-corroded during the photocatalytic reaction. The XRD pattern (Fig. 9) of the recycled C60/C3N4 composite after five runs of photoreaction is essentially similar to that of the original one, and there is no obvious variation in the locations and intensities of these peaks, suggesting that the C60/C3N4 composite has considerable photostability. To make the reaction mechanism clear, isopropanol (IPA), triethanolamine (TEOA) and p-benzoquinone (BQ) were respectively introduced as the scavengers of hydroxyl radicals (•OH), holes (h+) and superoxide radicals (•O2−) to examine the effects of reactive species on the photocatalytic degradation of RhB.45 The concentrations of IPA, TEOA and BQ in the reaction system were 10 mmol L−1, 10 mmol L−1 and 1 mmol L−1, respectively. In Fig. 10, we can see that BQ and TEOA lead to a remarkable suppression of the degradation rate of RhB, whereas IPA exhibits a weaker restraining effect on the

This journal is © The Royal Society of Chemistry 2014

View Article Online

Published on 14 October 2013. Downloaded by University of Hong Kong Libraries on 19/10/2014 10:11:06.

Dalton Transactions

Paper

Fig. 12 The proposed mechanism of enhanced photocatalytic activity for the C60/C3N4 composite. Fig. 10 The effect of reactive species on the photocatalytic degradation of RhB by 1 wt% C60/C3N4 composite.

Fig. 11 PL spectral changes with visible light irradiation time on the 1 wt% C60/C3N4 composite in a 5 × 10−4 M basic solution of TA.

degradation rate. The results confirm that h+ and •O2− play a more important role than •OH in the photocatalytic degradation of RhB. The formation of hydroxyl radicals (•OH) could be detected by the PL technique using terephthalic acid (TA) as a probe molecule. Experimental procedures were similar to the measurement of the photocatalytic activity except that the RhB aqueous solution was replaced by the 5 × 10−4 M TA aqueous solution with a concentration of 2 × 10−3 M NaOH solution. As shown in Fig. 11, a gradual increase in the PL intensity at about 430 nm was observed with increasing irradiation time, suggesting that the hydroxyl radicals were formed in the photocatalytic oxidation process. Based on the above results, it is evident that the interaction between C3N4 and C60 is responsible for the efficient generation and separation process of charge carriers under visible light irradiation. A clear synergetic effect mechanism is indicated according to the photocatalytic results. As shown in Fig. 12, C3N4 with a narrow band gap energy (2.85 eV in this work) could be easily excited by visible light and induce the generation of electrons and holes. It has been reported that the delocalized π structure of C60 facilitates the transfer of photoinduced electrons and could perform as an excellent

This journal is © The Royal Society of Chemistry 2014

electron acceptor.40 In the present system, the conduction band (CB) bottom potential and valance band (VB) top potential of C3N4 are −1.12 eV and 1.73 eV (vs. NHE),24 while the potential of C60/C60•− is −0.2 V (vs. NHE).40 The photogenerated electrons could be smoothly transferred from the CB of C3N4 to C60 under visible light irradiation. Therefore, the recombination of electrons and holes on the surface of C3N4 has been effectively inhibited. The photogenerated electrons probably react with dissolved O2 to yield •O2−, following which the oxidative species •OH is produced in the reaction of •O2− with photogenerated electrons. On the other hand, the VB potential of C3N4 (1.73 eV) is less positive than the standard redox potentials of •OH/OH− (2.38 V vs. NHE),46 indicating that the photogenerated holes on the C3N4 could not oxidize OH− into •OH. As a result, the degradation of RhB would be a reaction with photogenerated holes directly. The plausible reaction process could be proposed as the following: C60 =C3 N4 ! C60 ðe Þ=C3 N4 ðhþ Þ

ð2Þ

C60 ðe Þ þ O2 ! C60 þ • O2 

ð3Þ

O2  þ 2e þ 2Hþ ! • OH þ OH

ð4Þ

RhB þ hþ ð• OH; • O2  Þ ! products

ð5Þ



A better separation of photogenerated electrons and holes in the C60/C3N4 composite was confirmed using PL emission spectra of bare C3N4 and 1 wt% C60/C3N4 composite. It is well known that the PL signals of semiconductor materials result from a recombination of photoinduced charge carriers. In general, a lower PL intensity indicates a decrease in recombination rate of photogenerated charge carriers. As shown in Fig. 13, the main emission peak is centered at about 440 nm for the bare C3N4, which could be attributed to the band–band PL phenomenon with the energy of light approximately equal to the band gap energy of C3N4. Compared with that of C3N4 alone, the emission peak intensity of the C60/C3N4 composite decreases considerably, suggesting that the recombination of photogenerated charge carriers is inhibited moderately. The result of PL verifies that the C60/C3N4 composite could most effectively separate photogenerated electron–hole pairs.

Dalton Trans., 2014, 43, 982–989 | 987

View Article Online

Published on 14 October 2013. Downloaded by University of Hong Kong Libraries on 19/10/2014 10:11:06.

Paper

Dalton Transactions

Fig. 13 PL emission spectra of bare C3N4 and 1 wt% C60/C3N4 composite.

4.

Conclusions

In summary, the visible-light-driven C60/C3N4 composites were prepared by introducing C60 with a facile adsorption route and applied to photocatalytic degradation of RhB solution. The enhanced photocatalytic performance was suggested to be related to the synergetic effect between C3N4 and C60, which was regarded as favorable for the separation of photogenerated electrons and holes. Moreover, photocatalytic mechanism investigations demonstrated that h+ and •O2− played a key role in the C60/C3N4 composite under visible light illumination. The resulting C60/C3N4 composite may be a promising efficient photocatalyst for degradation of organic pollutants.

Acknowledgements This work was supported by the Program for Introduction (Training) Talents of Wuhan Polytechnic University (2012RZ12).

Notes and references 1 X. B. Chen, S. H. Shen, L. J. Guo and S. S. Mao, Chem. Rev., 2010, 110, 6503–6570. 2 X. L. Hu, G. S. Li and J. C. Yu, Langmuir, 2010, 26, 3031– 3039. 3 H. Tong, S. X. Ouyang, Y. P. Bi, N. Umezawa, M. Oshikiri and J. H. Ye, Adv. Mater., 2012, 24, 229–251. 4 X. B. Chen and S. S. Mao, Chem. Rev., 2007, 107, 2891– 2959. 5 B. X. Li and Y. F. Wang, J. Phys. Chem. C, 2010, 114, 890– 896. 6 N. Z. Bao, L. M. Shen, T. Takata and K. Domen, Chem. Mater., 2008, 20, 110–117. 7 X. X. Yu, J. G. Yu, B. Cheng and B. B. Huang, Chem.–Eur. J., 2009, 15, 6731–6739.

988 | Dalton Trans., 2014, 43, 982–989

8 B. Chai, T. Y. Peng, P. Zeng, X. H. Zhang and X. J. Liu, J. Phys. Chem. C, 2011, 115, 6149–6155. 9 J. Jiang and L. Z. Zhang, Chem.–Eur. J., 2011, 17, 3710– 3717. 10 Z. C. Wang, J. H. Liu and W. Chen, Dalton Trans., 2012, 41, 4866–4870. 11 Y. J. Cui, J. S. Zhang, G. G. Zhang, J. H. Huang, P. Liu, M. Antonietti and X. C. Wang, J. Mater. Chem., 2011, 21, 13032–13039. 12 G. G. Zhang, J. S. Zhang, M. W. Zhang and X. C. Wang, J. Mater. Chem., 2012, 22, 8083–8091. 13 J. H. Liu, T. K. Zhang, Z. C. Wang, G. Dawson and W. Chen, J. Mater. Chem., 2011, 21, 14398–14401. 14 F. Dong, L. W. Wu, Y. J. Sun, M. Fu, Z. B. Wu and S. C. Lee, J. Mater. Chem., 2011, 21, 15171–15174. 15 S. C. Yan, Z. S. Li and Z. G. Zou, Langmuir, 2009, 25, 10397– 10401. 16 Y. S. Jun, W. H. Hong, M. Antonietti and A. Thomas, Adv. Mater., 2009, 21, 4270–4274. 17 Y. J. Cui, J. H. Huang, X. Z. Fu and X. C. Wang, Catal. Sci. Technol., 2012, 2, 1396–1402. 18 S. B. Yang, Y. J. Gong, J. S. Zhang, L. Zhan, L. L. Ma, Z. Y. Fang, R. Vajtai, X. C. Wang and P. M. Ajayan, Adv. Mater., 2013, 25, 2452–2456. 19 X. F. Chen, J. S. Zhang, X. Z. Fu, M. Antonietti and X. C. Wang, J. Am. Chem. Soc., 2009, 131, 11658–11659. 20 J. S. Zhang, J. H. Sun, K. Maeda, K. Domen, P. Liu, M. Antonietti, X. Z. Fu and X. C. Wang, Energy Environ. Sci., 2011, 4, 675–678. 21 G. H. Dong, K. Zhao and L. Z. Zhang, Chem. Commun., 2012, 48, 6178–6180. 22 Y. J. Wang, R. Shi, J. Lin and Y. F. Zhu, Energy Environ. Sci., 2011, 4, 2922–2929. 23 L. M. Sun, X. Zhao, C. J. Jia, Y. X. Zhou, X. F. Cheng, P. Li, L. Liu and W. L. Fan, J. Mater. Chem., 2012, 22, 23428– 23438. 24 B. Chai, T. Y. Peng, J. Mao, K. Li and L. Zan, Phys. Chem. Chem. Phys., 2012, 14, 16745–16752. 25 H. Xu, J. Yan, Y. G. Xu, Y. H. Song, H. M. Li, J. X. Xia, C. J. Huang and H. L. Wan, Appl. Catal., B, 2013, 129, 182–193. 26 S. C. Yan, S. B. Lv, Z. S. Li and Z. G. Zou, Dalton Trans., 2010, 39, 1488–1491. 27 S. Kumar, T. Surendar, A. Baruah and V. Shanker, J. Mater. Chem. A, 2013, 1, 5333–5340. 28 C. S. Pan, J. Xu, Y. J. Wang, D. Li and Y. F. Zhu, Adv. Funct. Mater., 2012, 22, 1518–1524. 29 T. S. Jamil, M. Y. Ghaly, N. A. Fathy, T. A. Abd el-halim and L. Österlund, Sep. Purif. Technol., 2012, 98, 270–279. 30 J. W. Shi, H. J. Cui, J. W. Chen, M. L. Fu, B. Xu, H. Y. Luo and Z. L. Ye, J. Colloid Interface Sci., 2012, 388, 201–208. 31 W. Zhou, K. Pan, Y. Qu, F. F. Sun, C. G. Tian, Z. Y. Ren, G. H. Tian and H. G. Fu, Chemosphere, 2010, 81, 555–561. 32 T. Y. Peng, P. Zeng, D. N. Ke, X. J. Liu and X. H. Zhang, Energy Fuels, 2011, 25, 2203–2210.

This journal is © The Royal Society of Chemistry 2014

View Article Online

Published on 14 October 2013. Downloaded by University of Hong Kong Libraries on 19/10/2014 10:11:06.

Dalton Transactions

33 J. G. Yu, T. T. Ma and S. W. Liu, Phys. Chem. Chem. Phys., 2011, 13, 2491–3501. 34 Q. J. Xiang, J. G. Yu and M. Jaroniec, Chem. Soc. Rev., 2012, 41, 782–796. 35 Q. J. Xiang, J. G. Yu and M. Jaroniec, J. Phys. Chem. C, 2011, 115, 7355–7363. 36 G. Z. Liao, S. Chen, X. Quan, H. T. Yu and H. M. Zhao, J. Mater. Chem., 2012, 22, 2721–2726. 37 Y. G. Xu, H. Xu, L. Wang, J. Yan, H. M. Li, Y. H. Song, L. Y. Huang and G. B. Cai, Dalton Trans., 2013, 42, 7604– 7613. 38 L. Ge and C. C. Han, Appl. Catal., B: Environ., 2012, 117, 268–274. 39 H. B. Fu, T. G. Xu, S. B. Zhu and Y. F. Zhu, Environ. Sci. Technol., 2008, 42, 8064–8069.

This journal is © The Royal Society of Chemistry 2014

Paper

40 J. G. Yu, T. T. Ma, G. Liu and B. Cheng, Dalton Trans., 2011, 40, 6635–6644. 41 Y. Z. Long, Y. Lu, Y. Huang, Y. C. Peng, Y. J. Lu, S. Z. Kang and J. Mu, J. Phys. Chem. C, 2009, 113, 13899–13905. 42 S. B. Zhu, T. G. Xu, H. B. Fu, J. C. Zhao and Y. F. Zhu, Environ. Sci. Technol., 2007, 41, 6234–6239. 43 X. Zhao, H. J. Liu, Y. L. Shen and J. H. Qu, Appl. Catal., B: Environ., 2011, 106, 63–68. 44 J. Mao, T. Y. Peng, X. H. Zhang, K. Li, L. Q. Ye and L. Zan, Catal. Sci. Technol., 2013, 3, 1253–1260. 45 J. Cao, B. Y. Xu, H. L. Lin, B. D. Luo and S. F. Chen, Dalton Trans., 2012, 41, 11482–11490. 46 H. F. Cheng, B. B. Huang, Y. Dai, X. Y. Qin and X. Y. Zhang, Langmuir, 2010, 26, 6618–6624.

Dalton Trans., 2014, 43, 982–989 | 989

Fullerene modified C3N4 composites with enhanced photocatalytic activity under visible light irradiation.

Fullerene modified C3N4 (C60/C3N4) composites with efficient photocatalytic activity under visible light irradiation were fabricated by a simple adsor...
3MB Sizes 0 Downloads 0 Views