Abstract

In this report, we studied the optical properties of hybrid spherical structures consisting of alternating nanosheets of titania (TiO2) and graphene oxide (GO) prepared by a layer-by-layer self-assembly technique. Compared to samples with only TiO2 spheres or GO nanosheets, a blue-to-red light emission band emerges and persists in this novel composite material even after it was further reduced through microwave irradiation. From detailed time-resolved measurements and energy-level structure modeling, this unexpected fluorescent feature was attributed to the indirect optical transitions between TiO2 and the localized sp2 domains of GO in a charge-separated configuration.

© 2012 OSA

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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef]
  6. T. Yeh, F. Chan, C. Hsieh, and H. Teng, “Graphite oxide with different oxygenated levels for hydrogen and oxygen production from water under illumination: The band positions of graphite oxide,” J. Phys. Chem. C115(45), 22587–22597 (2011).
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  7. X. Wang, L. Zhi, and K. Müllen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett.8(1), 323–327 (2008).
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  8. J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
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  9. C. H. Lu, H. H. Yang, C. L. Zhu, X. Chen, and G. N. Chen, “A graphene platform for sensing biomolecules,” Angew. Chem. Int. Ed. Engl.48(26), 4785–4787 (2009).
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    [CrossRef] [PubMed]
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    [CrossRef]
  24. V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
    [CrossRef] [PubMed]
  25. A. Bagri, C. Mattevi, M. Acik, Y. J. Chabal, M. Chhowalla, and V. B. Shenoy, “Structural evolution during the reduction of chemically derived graphene oxide,” Nat. Chem.2(7), 581–587 (2010).
    [CrossRef] [PubMed]
  26. K. K. Manga, Y. Zhou, Y. Yan, and K. P. Loh, “Multilayer hybrid films consisting of alternating graphene and titania nanosheets with ultrafast electron transfer and photoconversion properties,” Adv. Funct. Mater.19(22), 3638–3643 (2009).
    [CrossRef]

2012

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

2011

Y. T. Liang, B. K. Vijayan, K. A. Gray, and M. C. Hersam, “Minimizing graphene defects enhances titania nanocomposite-based photocatalytic reduction of CO2 for improved solar fuel production,” Nano Lett.11(7), 2865–2870 (2011).
[CrossRef] [PubMed]

Z. X. Gan, S. J. Xiong, X. L. Wu, C. Y. He, J. C. Shen, and P. K. Chu, “Mn2+-bonded reduced graphene oxide with strong radiative recombination in broad visible range caused by resonant energy transfer,” Nano Lett.11(9), 3951–3956 (2011).
[CrossRef] [PubMed]

T. Yeh, F. Chan, C. Hsieh, and H. Teng, “Graphite oxide with different oxygenated levels for hydrogen and oxygen production from water under illumination: The band positions of graphite oxide,” J. Phys. Chem. C115(45), 22587–22597 (2011).
[CrossRef]

2010

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
[CrossRef] [PubMed]

K. P. Loh, Q. Bao, G. Eda, and M. Chhowalla, “Graphene oxide as a chemically tunable platform for optical applications,” Nat. Chem.2(12), 1015–1024 (2010).
[CrossRef] [PubMed]

G. Eda and M. Chhowalla, “Chemically derived graphene oxide: Towards large-area thin-film electronics and optoelectronics,” Adv. Mater. (Deerfield Beach Fla.)22(22), 2392–2415 (2010).
[CrossRef] [PubMed]

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

D. Pan, J. Zhang, Z. Li, and M. Wu, “Hydrothermal route for cutting graphene sheets into blue-luminescent graphene quantum dots,” Adv. Mater. (Deerfield Beach Fla.)22(6), 734–738 (2010).
[CrossRef] [PubMed]

Q. Mei, K. Zhang, G. Guan, B. Liu, S. Wang, and Z. Zhang, “Highly efficient photoluminescent graphene oxide with tunable surface properties,” Chem. Commun. (Camb.)46(39), 7319–7321 (2010).
[CrossRef] [PubMed]

H. Zhang, X. Lv, Y. Li, Y. Wang, and J. Li, “P25-graphene composite as a high performance photocatalyst,” ACS Nano4(1), 380–386 (2010).
[CrossRef] [PubMed]

J. Hensel, G. Wang, Y. Li, and J. Z. Zhang, “Synergistic effect of CdSe quantum dot sensitization and nitrogen doping of TiO2 nanostructures for photoelectrochemical solar hydrogen generation,” Nano Lett.10(2), 478–483 (2010).
[CrossRef] [PubMed]

A. Bagri, C. Mattevi, M. Acik, Y. J. Chabal, M. Chhowalla, and V. B. Shenoy, “Structural evolution during the reduction of chemically derived graphene oxide,” Nat. Chem.2(7), 581–587 (2010).
[CrossRef] [PubMed]

2009

K. K. Manga, Y. Zhou, Y. Yan, and K. P. Loh, “Multilayer hybrid films consisting of alternating graphene and titania nanosheets with ultrafast electron transfer and photoconversion properties,” Adv. Funct. Mater.19(22), 3638–3643 (2009).
[CrossRef]

K. Woan, G. Pyrgiotakis, and W. Sigmund, “Photocatalytic carbon-nanotube-TiO2 composites,” Adv. Mater. (Deerfield Beach Fla.)21(21), 2233–2239 (2009).
[CrossRef]

Z. Luo, P. M. Vora, E. J. Mele, A. T. C. Johnson, and J. M. Kikkawa, “Photoluminescence and band gap modulation in graphene oxide,” Appl. Phys. Lett.94(11), 111909 (2009).
[CrossRef]

C. H. Lu, H. H. Yang, C. L. Zhu, X. Chen, and G. N. Chen, “A graphene platform for sensing biomolecules,” Angew. Chem. Int. Ed. Engl.48(26), 4785–4787 (2009).
[CrossRef] [PubMed]

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

2008

X. Wang, L. Zhi, and K. Müllen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett.8(1), 323–327 (2008).
[CrossRef] [PubMed]

X. Sun, Z. Liu, K. Welsher, J. T. Robinson, A. Goodwin, S. Zaric, and H. Dai, “Nano-graphene oxide for cellular imaging and drug delivery,” Nano Res1(3), 203–212 (2008).
[CrossRef] [PubMed]

J. Ito, J. Nakamura, and A. Natori, “Semiconducting nature of the oxygen-adsorbed graphene sheet,” J. Appl. Phys.103(11), 113712 (2008).
[CrossRef]

2007

V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
[CrossRef] [PubMed]

2006

N. D. Abazović, M. I. Čomor, M. D. Dramićanin, D. J. Jovanović, S. P. Ahrenkiel, and J. M. Nedeljković, “Photoluminescence of anatase and rutile TiO2 particles,” J. Phys. Chem. B110(50), 25366–25370 (2006).
[CrossRef] [PubMed]

2000

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

1997

T. Sasaki and M. Watanabe, “Semiconductor nanosheet crystallites of quasi-TiO2 and their optical properties,” J. Phys. Chem. B101(49), 10159–10161 (1997).
[CrossRef]

Abazovic, N. D.

N. D. Abazović, M. I. Čomor, M. D. Dramićanin, D. J. Jovanović, S. P. Ahrenkiel, and J. M. Nedeljković, “Photoluminescence of anatase and rutile TiO2 particles,” J. Phys. Chem. B110(50), 25366–25370 (2006).
[CrossRef] [PubMed]

Achermann, M.

V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
[CrossRef] [PubMed]

Acik, M.

A. Bagri, C. Mattevi, M. Acik, Y. J. Chabal, M. Chhowalla, and V. B. Shenoy, “Structural evolution during the reduction of chemically derived graphene oxide,” Nat. Chem.2(7), 581–587 (2010).
[CrossRef] [PubMed]

Agrawal, M.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
[CrossRef] [PubMed]

Ahrenkiel, S. P.

N. D. Abazović, M. I. Čomor, M. D. Dramićanin, D. J. Jovanović, S. P. Ahrenkiel, and J. M. Nedeljković, “Photoluminescence of anatase and rutile TiO2 particles,” J. Phys. Chem. B110(50), 25366–25370 (2006).
[CrossRef] [PubMed]

Bagri, A.

A. Bagri, C. Mattevi, M. Acik, Y. J. Chabal, M. Chhowalla, and V. B. Shenoy, “Structural evolution during the reduction of chemically derived graphene oxide,” Nat. Chem.2(7), 581–587 (2010).
[CrossRef] [PubMed]

Balmer, M. L.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Bao, Q.

K. P. Loh, Q. Bao, G. Eda, and M. Chhowalla, “Graphene oxide as a chemically tunable platform for optical applications,” Nat. Chem.2(12), 1015–1024 (2010).
[CrossRef] [PubMed]

Bao, Z.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
[CrossRef] [PubMed]

Becerril, H. A.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
[CrossRef] [PubMed]

Bezel, I.

V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
[CrossRef] [PubMed]

Blake, D. M.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Bowman, M. K.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Chabal, Y. J.

A. Bagri, C. Mattevi, M. Acik, Y. J. Chabal, M. Chhowalla, and V. B. Shenoy, “Structural evolution during the reduction of chemically derived graphene oxide,” Nat. Chem.2(7), 581–587 (2010).
[CrossRef] [PubMed]

Chan, F.

T. Yeh, F. Chan, C. Hsieh, and H. Teng, “Graphite oxide with different oxygenated levels for hydrogen and oxygen production from water under illumination: The band positions of graphite oxide,” J. Phys. Chem. C115(45), 22587–22597 (2011).
[CrossRef]

Chen, C. W.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

Chen, G. N.

C. H. Lu, H. H. Yang, C. L. Zhu, X. Chen, and G. N. Chen, “A graphene platform for sensing biomolecules,” Angew. Chem. Int. Ed. Engl.48(26), 4785–4787 (2009).
[CrossRef] [PubMed]

Chen, H. A.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

Chen, I. S.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

Chen, K. H.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Chen, L. C.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Chen, M.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Chen, X.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

C. H. Lu, H. H. Yang, C. L. Zhu, X. Chen, and G. N. Chen, “A graphene platform for sensing biomolecules,” Angew. Chem. Int. Ed. Engl.48(26), 4785–4787 (2009).
[CrossRef] [PubMed]

Chen, Y.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
[CrossRef] [PubMed]

Chhowalla, M.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

K. P. Loh, Q. Bao, G. Eda, and M. Chhowalla, “Graphene oxide as a chemically tunable platform for optical applications,” Nat. Chem.2(12), 1015–1024 (2010).
[CrossRef] [PubMed]

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

A. Bagri, C. Mattevi, M. Acik, Y. J. Chabal, M. Chhowalla, and V. B. Shenoy, “Structural evolution during the reduction of chemically derived graphene oxide,” Nat. Chem.2(7), 581–587 (2010).
[CrossRef] [PubMed]

G. Eda and M. Chhowalla, “Chemically derived graphene oxide: Towards large-area thin-film electronics and optoelectronics,” Adv. Mater. (Deerfield Beach Fla.)22(22), 2392–2415 (2010).
[CrossRef] [PubMed]

Chien, C. T.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Chu, P. K.

Z. X. Gan, S. J. Xiong, X. L. Wu, C. Y. He, J. C. Shen, and P. K. Chu, “Mn2+-bonded reduced graphene oxide with strong radiative recombination in broad visible range caused by resonant energy transfer,” Nano Lett.11(9), 3951–3956 (2011).
[CrossRef] [PubMed]

Comor, M. I.

N. D. Abazović, M. I. Čomor, M. D. Dramićanin, D. J. Jovanović, S. P. Ahrenkiel, and J. M. Nedeljković, “Photoluminescence of anatase and rutile TiO2 particles,” J. Phys. Chem. B110(50), 25366–25370 (2006).
[CrossRef] [PubMed]

Cot, F. M.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Dai, H.

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

X. Sun, Z. Liu, K. Welsher, J. T. Robinson, A. Goodwin, S. Zaric, and H. Dai, “Nano-graphene oxide for cellular imaging and drug delivery,” Nano Res1(3), 203–212 (2008).
[CrossRef] [PubMed]

Dramicanin, M. D.

N. D. Abazović, M. I. Čomor, M. D. Dramićanin, D. J. Jovanović, S. P. Ahrenkiel, and J. M. Nedeljković, “Photoluminescence of anatase and rutile TiO2 particles,” J. Phys. Chem. B110(50), 25366–25370 (2006).
[CrossRef] [PubMed]

Eda, G.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

K. P. Loh, Q. Bao, G. Eda, and M. Chhowalla, “Graphene oxide as a chemically tunable platform for optical applications,” Nat. Chem.2(12), 1015–1024 (2010).
[CrossRef] [PubMed]

G. Eda and M. Chhowalla, “Chemically derived graphene oxide: Towards large-area thin-film electronics and optoelectronics,” Adv. Mater. (Deerfield Beach Fla.)22(22), 2392–2415 (2010).
[CrossRef] [PubMed]

Elder, S. H.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Fujita, T.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Gan, Z. X.

Z. X. Gan, S. J. Xiong, X. L. Wu, C. Y. He, J. C. Shen, and P. K. Chu, “Mn2+-bonded reduced graphene oxide with strong radiative recombination in broad visible range caused by resonant energy transfer,” Nano Lett.11(9), 3951–3956 (2011).
[CrossRef] [PubMed]

Gao, J.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

Gao, Y.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Goodwin, A.

X. Sun, Z. Liu, K. Welsher, J. T. Robinson, A. Goodwin, S. Zaric, and H. Dai, “Nano-graphene oxide for cellular imaging and drug delivery,” Nano Res1(3), 203–212 (2008).
[CrossRef] [PubMed]

Gray, K. A.

Y. T. Liang, B. K. Vijayan, K. A. Gray, and M. C. Hersam, “Minimizing graphene defects enhances titania nanocomposite-based photocatalytic reduction of CO2 for improved solar fuel production,” Nano Lett.11(7), 2865–2870 (2011).
[CrossRef] [PubMed]

Guan, G.

Q. Mei, K. Zhang, G. Guan, B. Liu, S. Wang, and Z. Zhang, “Highly efficient photoluminescent graphene oxide with tunable surface properties,” Chem. Commun. (Camb.)46(39), 7319–7321 (2010).
[CrossRef] [PubMed]

Guo, J.

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

He, C. Y.

Z. X. Gan, S. J. Xiong, X. L. Wu, C. Y. He, J. C. Shen, and P. K. Chu, “Mn2+-bonded reduced graphene oxide with strong radiative recombination in broad visible range caused by resonant energy transfer,” Nano Lett.11(9), 3951–3956 (2011).
[CrossRef] [PubMed]

Heald, S. M.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Hensel, J.

J. Hensel, G. Wang, Y. Li, and J. Z. Zhang, “Synergistic effect of CdSe quantum dot sensitization and nitrogen doping of TiO2 nanostructures for photoelectrochemical solar hydrogen generation,” Nano Lett.10(2), 478–483 (2010).
[CrossRef] [PubMed]

Hersam, M. C.

Y. T. Liang, B. K. Vijayan, K. A. Gray, and M. C. Hersam, “Minimizing graphene defects enhances titania nanocomposite-based photocatalytic reduction of CO2 for improved solar fuel production,” Nano Lett.11(7), 2865–2870 (2011).
[CrossRef] [PubMed]

Hsieh, C.

T. Yeh, F. Chan, C. Hsieh, and H. Teng, “Graphite oxide with different oxygenated levels for hydrogen and oxygen production from water under illumination: The band positions of graphite oxide,” J. Phys. Chem. C115(45), 22587–22597 (2011).
[CrossRef]

Isoda, S.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Ito, J.

J. Ito, J. Nakamura, and A. Natori, “Semiconducting nature of the oxygen-adsorbed graphene sheet,” J. Appl. Phys.103(11), 113712 (2008).
[CrossRef]

Ivanov, S. A.

V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
[CrossRef] [PubMed]

Johnson, A. T. C.

Z. Luo, P. M. Vora, E. J. Mele, A. T. C. Johnson, and J. M. Kikkawa, “Photoluminescence and band gap modulation in graphene oxide,” Appl. Phys. Lett.94(11), 111909 (2009).
[CrossRef]

Joly, A. G.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Jovanovic, D. J.

N. D. Abazović, M. I. Čomor, M. D. Dramićanin, D. J. Jovanović, S. P. Ahrenkiel, and J. M. Nedeljković, “Photoluminescence of anatase and rutile TiO2 particles,” J. Phys. Chem. B110(50), 25366–25370 (2006).
[CrossRef] [PubMed]

Kikkawa, J. M.

Z. Luo, P. M. Vora, E. J. Mele, A. T. C. Johnson, and J. M. Kikkawa, “Photoluminescence and band gap modulation in graphene oxide,” Appl. Phys. Lett.94(11), 111909 (2009).
[CrossRef]

Klimov, V. I.

V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
[CrossRef] [PubMed]

Kolwaite, A. C.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Lai, W. J.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Li, J.

H. Zhang, X. Lv, Y. Li, Y. Wang, and J. Li, “P25-graphene composite as a high performance photocatalyst,” ACS Nano4(1), 380–386 (2010).
[CrossRef] [PubMed]

Li, S. S.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Li, X.

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

Li, Y.

J. Hensel, G. Wang, Y. Li, and J. Z. Zhang, “Synergistic effect of CdSe quantum dot sensitization and nitrogen doping of TiO2 nanostructures for photoelectrochemical solar hydrogen generation,” Nano Lett.10(2), 478–483 (2010).
[CrossRef] [PubMed]

H. Zhang, X. Lv, Y. Li, Y. Wang, and J. Li, “P25-graphene composite as a high performance photocatalyst,” ACS Nano4(1), 380–386 (2010).
[CrossRef] [PubMed]

Li, Z.

D. Pan, J. Zhang, Z. Li, and M. Wu, “Hydrothermal route for cutting graphene sheets into blue-luminescent graphene quantum dots,” Adv. Mater. (Deerfield Beach Fla.)22(6), 734–738 (2010).
[CrossRef] [PubMed]

Liang, Y. T.

Y. T. Liang, B. K. Vijayan, K. A. Gray, and M. C. Hersam, “Minimizing graphene defects enhances titania nanocomposite-based photocatalytic reduction of CO2 for improved solar fuel production,” Nano Lett.11(7), 2865–2870 (2011).
[CrossRef] [PubMed]

Lin, Y. Y.

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

Liu, B.

Q. Mei, K. Zhang, G. Guan, B. Liu, S. Wang, and Z. Zhang, “Highly efficient photoluminescent graphene oxide with tunable surface properties,” Chem. Commun. (Camb.)46(39), 7319–7321 (2010).
[CrossRef] [PubMed]

Liu, J.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

Liu, Q.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

Liu, Z.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
[CrossRef] [PubMed]

X. Sun, Z. Liu, K. Welsher, J. T. Robinson, A. Goodwin, S. Zaric, and H. Dai, “Nano-graphene oxide for cellular imaging and drug delivery,” Nano Res1(3), 203–212 (2008).
[CrossRef] [PubMed]

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K. P. Loh, Q. Bao, G. Eda, and M. Chhowalla, “Graphene oxide as a chemically tunable platform for optical applications,” Nat. Chem.2(12), 1015–1024 (2010).
[CrossRef] [PubMed]

K. K. Manga, Y. Zhou, Y. Yan, and K. P. Loh, “Multilayer hybrid films consisting of alternating graphene and titania nanosheets with ultrafast electron transfer and photoconversion properties,” Adv. Funct. Mater.19(22), 3638–3643 (2009).
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C. H. Lu, H. H. Yang, C. L. Zhu, X. Chen, and G. N. Chen, “A graphene platform for sensing biomolecules,” Angew. Chem. Int. Ed. Engl.48(26), 4785–4787 (2009).
[CrossRef] [PubMed]

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Z. Luo, P. M. Vora, E. J. Mele, A. T. C. Johnson, and J. M. Kikkawa, “Photoluminescence and band gap modulation in graphene oxide,” Appl. Phys. Lett.94(11), 111909 (2009).
[CrossRef]

Lv, X.

H. Zhang, X. Lv, Y. Li, Y. Wang, and J. Li, “P25-graphene composite as a high performance photocatalyst,” ACS Nano4(1), 380–386 (2010).
[CrossRef] [PubMed]

Magrini, K. A.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Manga, K. K.

K. K. Manga, Y. Zhou, Y. Yan, and K. P. Loh, “Multilayer hybrid films consisting of alternating graphene and titania nanosheets with ultrafast electron transfer and photoconversion properties,” Adv. Funct. Mater.19(22), 3638–3643 (2009).
[CrossRef]

Mattevi, C.

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

A. Bagri, C. Mattevi, M. Acik, Y. J. Chabal, M. Chhowalla, and V. B. Shenoy, “Structural evolution during the reduction of chemically derived graphene oxide,” Nat. Chem.2(7), 581–587 (2010).
[CrossRef] [PubMed]

McGuire, J. A.

V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
[CrossRef] [PubMed]

Mei, Q.

Q. Mei, K. Zhang, G. Guan, B. Liu, S. Wang, and Z. Zhang, “Highly efficient photoluminescent graphene oxide with tunable surface properties,” Chem. Commun. (Camb.)46(39), 7319–7321 (2010).
[CrossRef] [PubMed]

Mele, E. J.

Z. Luo, P. M. Vora, E. J. Mele, A. T. C. Johnson, and J. M. Kikkawa, “Photoluminescence and band gap modulation in graphene oxide,” Appl. Phys. Lett.94(11), 111909 (2009).
[CrossRef]

Müllen, K.

X. Wang, L. Zhi, and K. Müllen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett.8(1), 323–327 (2008).
[CrossRef] [PubMed]

Nakamura, J.

J. Ito, J. Nakamura, and A. Natori, “Semiconducting nature of the oxygen-adsorbed graphene sheet,” J. Appl. Phys.103(11), 113712 (2008).
[CrossRef]

Nanda, J.

V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
[CrossRef] [PubMed]

Natori, A.

J. Ito, J. Nakamura, and A. Natori, “Semiconducting nature of the oxygen-adsorbed graphene sheet,” J. Appl. Phys.103(11), 113712 (2008).
[CrossRef]

Nedeljkovic, J. M.

N. D. Abazović, M. I. Čomor, M. D. Dramićanin, D. J. Jovanović, S. P. Ahrenkiel, and J. M. Nedeljković, “Photoluminescence of anatase and rutile TiO2 particles,” J. Phys. Chem. B110(50), 25366–25370 (2006).
[CrossRef] [PubMed]

Nemoto, T.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Pan, D.

D. Pan, J. Zhang, Z. Li, and M. Wu, “Hydrothermal route for cutting graphene sheets into blue-luminescent graphene quantum dots,” Adv. Mater. (Deerfield Beach Fla.)22(6), 734–738 (2010).
[CrossRef] [PubMed]

Peumans, P.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
[CrossRef] [PubMed]

Piryatinski, A.

V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
[CrossRef] [PubMed]

Pyrgiotakis, G.

K. Woan, G. Pyrgiotakis, and W. Sigmund, “Photocatalytic carbon-nanotube-TiO2 composites,” Adv. Mater. (Deerfield Beach Fla.)21(21), 2233–2239 (2009).
[CrossRef]

Robinson, J. T.

X. Sun, Z. Liu, K. Welsher, J. T. Robinson, A. Goodwin, S. Zaric, and H. Dai, “Nano-graphene oxide for cellular imaging and drug delivery,” Nano Res1(3), 203–212 (2008).
[CrossRef] [PubMed]

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T. Sasaki and M. Watanabe, “Semiconductor nanosheet crystallites of quasi-TiO2 and their optical properties,” J. Phys. Chem. B101(49), 10159–10161 (1997).
[CrossRef]

Shen, J. C.

Z. X. Gan, S. J. Xiong, X. L. Wu, C. Y. He, J. C. Shen, and P. K. Chu, “Mn2+-bonded reduced graphene oxide with strong radiative recombination in broad visible range caused by resonant energy transfer,” Nano Lett.11(9), 3951–3956 (2011).
[CrossRef] [PubMed]

Shenoy, V. B.

A. Bagri, C. Mattevi, M. Acik, Y. J. Chabal, M. Chhowalla, and V. B. Shenoy, “Structural evolution during the reduction of chemically derived graphene oxide,” Nat. Chem.2(7), 581–587 (2010).
[CrossRef] [PubMed]

Sigmund, W.

K. Woan, G. Pyrgiotakis, and W. Sigmund, “Photocatalytic carbon-nanotube-TiO2 composites,” Adv. Mater. (Deerfield Beach Fla.)21(21), 2233–2239 (2009).
[CrossRef]

Su, Y.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Sun, X.

X. Sun, Z. Liu, K. Welsher, J. T. Robinson, A. Goodwin, S. Zaric, and H. Dai, “Nano-graphene oxide for cellular imaging and drug delivery,” Nano Res1(3), 203–212 (2008).
[CrossRef] [PubMed]

Teng, H.

T. Yeh, F. Chan, C. Hsieh, and H. Teng, “Graphite oxide with different oxygenated levels for hydrogen and oxygen production from water under illumination: The band positions of graphite oxide,” J. Phys. Chem. C115(45), 22587–22597 (2011).
[CrossRef]

Tian, Z.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

Tu, W.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

Tyryshkin, A. M.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
[CrossRef]

Vijayan, B. K.

Y. T. Liang, B. K. Vijayan, K. A. Gray, and M. C. Hersam, “Minimizing graphene defects enhances titania nanocomposite-based photocatalytic reduction of CO2 for improved solar fuel production,” Nano Lett.11(7), 2865–2870 (2011).
[CrossRef] [PubMed]

Vora, P. M.

Z. Luo, P. M. Vora, E. J. Mele, A. T. C. Johnson, and J. M. Kikkawa, “Photoluminescence and band gap modulation in graphene oxide,” Appl. Phys. Lett.94(11), 111909 (2009).
[CrossRef]

Wang, G.

J. Hensel, G. Wang, Y. Li, and J. Z. Zhang, “Synergistic effect of CdSe quantum dot sensitization and nitrogen doping of TiO2 nanostructures for photoelectrochemical solar hydrogen generation,” Nano Lett.10(2), 478–483 (2010).
[CrossRef] [PubMed]

Wang, H.

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

Wang, S.

Q. Mei, K. Zhang, G. Guan, B. Liu, S. Wang, and Z. Zhang, “Highly efficient photoluminescent graphene oxide with tunable surface properties,” Chem. Commun. (Camb.)46(39), 7319–7321 (2010).
[CrossRef] [PubMed]

Wang, X.

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

X. Wang, L. Zhi, and K. Müllen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett.8(1), 323–327 (2008).
[CrossRef] [PubMed]

Wang, Y.

H. Zhang, X. Lv, Y. Li, Y. Wang, and J. Li, “P25-graphene composite as a high performance photocatalyst,” ACS Nano4(1), 380–386 (2010).
[CrossRef] [PubMed]

Watanabe, M.

T. Sasaki and M. Watanabe, “Semiconductor nanosheet crystallites of quasi-TiO2 and their optical properties,” J. Phys. Chem. B101(49), 10159–10161 (1997).
[CrossRef]

Weber, P. K.

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

Welsher, K.

X. Sun, Z. Liu, K. Welsher, J. T. Robinson, A. Goodwin, S. Zaric, and H. Dai, “Nano-graphene oxide for cellular imaging and drug delivery,” Nano Res1(3), 203–212 (2008).
[CrossRef] [PubMed]

Woan, K.

K. Woan, G. Pyrgiotakis, and W. Sigmund, “Photocatalytic carbon-nanotube-TiO2 composites,” Adv. Mater. (Deerfield Beach Fla.)21(21), 2233–2239 (2009).
[CrossRef]

Wu, J.

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
[CrossRef] [PubMed]

Wu, M.

D. Pan, J. Zhang, Z. Li, and M. Wu, “Hydrothermal route for cutting graphene sheets into blue-luminescent graphene quantum dots,” Adv. Mater. (Deerfield Beach Fla.)22(6), 734–738 (2010).
[CrossRef] [PubMed]

Wu, X. L.

Z. X. Gan, S. J. Xiong, X. L. Wu, C. Y. He, J. C. Shen, and P. K. Chu, “Mn2+-bonded reduced graphene oxide with strong radiative recombination in broad visible range caused by resonant energy transfer,” Nano Lett.11(9), 3951–3956 (2011).
[CrossRef] [PubMed]

Xiong, S. J.

Z. X. Gan, S. J. Xiong, X. L. Wu, C. Y. He, J. C. Shen, and P. K. Chu, “Mn2+-bonded reduced graphene oxide with strong radiative recombination in broad visible range caused by resonant energy transfer,” Nano Lett.11(9), 3951–3956 (2011).
[CrossRef] [PubMed]

Yamaguchi, H.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

Yan, Y.

K. K. Manga, Y. Zhou, Y. Yan, and K. P. Loh, “Multilayer hybrid films consisting of alternating graphene and titania nanosheets with ultrafast electron transfer and photoconversion properties,” Adv. Funct. Mater.19(22), 3638–3643 (2009).
[CrossRef]

Yang, H. H.

C. H. Lu, H. H. Yang, C. L. Zhu, X. Chen, and G. N. Chen, “A graphene platform for sensing biomolecules,” Angew. Chem. Int. Ed. Engl.48(26), 4785–4787 (2009).
[CrossRef] [PubMed]

Yeh, T.

T. Yeh, F. Chan, C. Hsieh, and H. Teng, “Graphite oxide with different oxygenated levels for hydrogen and oxygen production from water under illumination: The band positions of graphite oxide,” J. Phys. Chem. C115(45), 22587–22597 (2011).
[CrossRef]

Yeh, Y. C.

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Yoon, Y.

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

Zaric, S.

X. Sun, Z. Liu, K. Welsher, J. T. Robinson, A. Goodwin, S. Zaric, and H. Dai, “Nano-graphene oxide for cellular imaging and drug delivery,” Nano Res1(3), 203–212 (2008).
[CrossRef] [PubMed]

Zhang, H.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

H. Zhang, X. Lv, Y. Li, Y. Wang, and J. Li, “P25-graphene composite as a high performance photocatalyst,” ACS Nano4(1), 380–386 (2010).
[CrossRef] [PubMed]

Zhang, J.

D. Pan, J. Zhang, Z. Li, and M. Wu, “Hydrothermal route for cutting graphene sheets into blue-luminescent graphene quantum dots,” Adv. Mater. (Deerfield Beach Fla.)22(6), 734–738 (2010).
[CrossRef] [PubMed]

Zhang, J. Z.

J. Hensel, G. Wang, Y. Li, and J. Z. Zhang, “Synergistic effect of CdSe quantum dot sensitization and nitrogen doping of TiO2 nanostructures for photoelectrochemical solar hydrogen generation,” Nano Lett.10(2), 478–483 (2010).
[CrossRef] [PubMed]

Zhang, K.

Q. Mei, K. Zhang, G. Guan, B. Liu, S. Wang, and Z. Zhang, “Highly efficient photoluminescent graphene oxide with tunable surface properties,” Chem. Commun. (Camb.)46(39), 7319–7321 (2010).
[CrossRef] [PubMed]

Zhang, L.

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

Zhang, Z.

Q. Mei, K. Zhang, G. Guan, B. Liu, S. Wang, and Z. Zhang, “Highly efficient photoluminescent graphene oxide with tunable surface properties,” Chem. Commun. (Camb.)46(39), 7319–7321 (2010).
[CrossRef] [PubMed]

Zhi, L.

X. Wang, L. Zhi, and K. Müllen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett.8(1), 323–327 (2008).
[CrossRef] [PubMed]

Zhou, Y.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

K. K. Manga, Y. Zhou, Y. Yan, and K. P. Loh, “Multilayer hybrid films consisting of alternating graphene and titania nanosheets with ultrafast electron transfer and photoconversion properties,” Adv. Funct. Mater.19(22), 3638–3643 (2009).
[CrossRef]

Zhu, C. L.

C. H. Lu, H. H. Yang, C. L. Zhu, X. Chen, and G. N. Chen, “A graphene platform for sensing biomolecules,” Angew. Chem. Int. Ed. Engl.48(26), 4785–4787 (2009).
[CrossRef] [PubMed]

Zou, Z.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

ACS Nano

J. Wu, M. Agrawal, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, “Organic light-emitting diodes on solution-processed graphene transparent electrodes,” ACS Nano4(1), 43–48 (2010).
[CrossRef] [PubMed]

H. Zhang, X. Lv, Y. Li, Y. Wang, and J. Li, “P25-graphene composite as a high performance photocatalyst,” ACS Nano4(1), 380–386 (2010).
[CrossRef] [PubMed]

Adv. Funct. Mater.

W. Tu, Y. Zhou, Q. Liu, Z. Tian, J. Gao, X. Chen, H. Zhang, J. Liu, and Z. Zou, “Robust hollow spheres consisting of alternating titania nanosheets and graphene nanosheets with high photocatalytic activity for CO2 conversion into renewable fuels,” Adv. Funct. Mater.22(6), 1215–1221 (2012).
[CrossRef]

K. K. Manga, Y. Zhou, Y. Yan, and K. P. Loh, “Multilayer hybrid films consisting of alternating graphene and titania nanosheets with ultrafast electron transfer and photoconversion properties,” Adv. Funct. Mater.19(22), 3638–3643 (2009).
[CrossRef]

Adv. Mater. (Deerfield Beach Fla.)

D. Pan, J. Zhang, Z. Li, and M. Wu, “Hydrothermal route for cutting graphene sheets into blue-luminescent graphene quantum dots,” Adv. Mater. (Deerfield Beach Fla.)22(6), 734–738 (2010).
[CrossRef] [PubMed]

K. Woan, G. Pyrgiotakis, and W. Sigmund, “Photocatalytic carbon-nanotube-TiO2 composites,” Adv. Mater. (Deerfield Beach Fla.)21(21), 2233–2239 (2009).
[CrossRef]

G. Eda and M. Chhowalla, “Chemically derived graphene oxide: Towards large-area thin-film electronics and optoelectronics,” Adv. Mater. (Deerfield Beach Fla.)22(22), 2392–2415 (2010).
[CrossRef] [PubMed]

G. Eda, Y. Y. Lin, C. Mattevi, H. Yamaguchi, H. A. Chen, I. S. Chen, C. W. Chen, and M. Chhowalla, “Blue photoluminescence from chemically derived graphene oxide,” Adv. Mater. (Deerfield Beach Fla.)22(4), 505–509 (2010).
[CrossRef] [PubMed]

Angew. Chem. Int. Ed. Engl.

C. H. Lu, H. H. Yang, C. L. Zhu, X. Chen, and G. N. Chen, “A graphene platform for sensing biomolecules,” Angew. Chem. Int. Ed. Engl.48(26), 4785–4787 (2009).
[CrossRef] [PubMed]

C. T. Chien, S. S. Li, W. J. Lai, Y. C. Yeh, H. A. Chen, I. S. Chen, L. C. Chen, K. H. Chen, T. Nemoto, S. Isoda, M. Chen, T. Fujita, G. Eda, H. Yamaguchi, M. Chhowalla, and C. W. Chen, “Tunable photoluminescence from graphene oxide,” Angew. Chem. Int. Ed. Engl.51(27), 6662–6666 (2012).
[CrossRef] [PubMed]

Appl. Phys. Lett.

Z. Luo, P. M. Vora, E. J. Mele, A. T. C. Johnson, and J. M. Kikkawa, “Photoluminescence and band gap modulation in graphene oxide,” Appl. Phys. Lett.94(11), 111909 (2009).
[CrossRef]

Chem. Commun. (Camb.)

Q. Mei, K. Zhang, G. Guan, B. Liu, S. Wang, and Z. Zhang, “Highly efficient photoluminescent graphene oxide with tunable surface properties,” Chem. Commun. (Camb.)46(39), 7319–7321 (2010).
[CrossRef] [PubMed]

J. Am. Chem. Soc.

S. H. Elder, F. M. Cot, Y. Su, S. M. Heald, A. M. Tyryshkin, M. K. Bowman, Y. Gao, A. G. Joly, M. L. Balmer, A. C. Kolwaite, K. A. Magrini, and D. M. Blake, “The discovery and study of nanocrystalline TiO2-(MoO3) core-shell materials,” J. Am. Chem. Soc.122(21), 5138–5146 (2000).
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J. Appl. Phys.

J. Ito, J. Nakamura, and A. Natori, “Semiconducting nature of the oxygen-adsorbed graphene sheet,” J. Appl. Phys.103(11), 113712 (2008).
[CrossRef]

J. Phys. Chem. B

T. Sasaki and M. Watanabe, “Semiconductor nanosheet crystallites of quasi-TiO2 and their optical properties,” J. Phys. Chem. B101(49), 10159–10161 (1997).
[CrossRef]

N. D. Abazović, M. I. Čomor, M. D. Dramićanin, D. J. Jovanović, S. P. Ahrenkiel, and J. M. Nedeljković, “Photoluminescence of anatase and rutile TiO2 particles,” J. Phys. Chem. B110(50), 25366–25370 (2006).
[CrossRef] [PubMed]

J. Phys. Chem. C

T. Yeh, F. Chan, C. Hsieh, and H. Teng, “Graphite oxide with different oxygenated levels for hydrogen and oxygen production from water under illumination: The band positions of graphite oxide,” J. Phys. Chem. C115(45), 22587–22597 (2011).
[CrossRef]

Nano Lett.

X. Wang, L. Zhi, and K. Müllen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett.8(1), 323–327 (2008).
[CrossRef] [PubMed]

Z. X. Gan, S. J. Xiong, X. L. Wu, C. Y. He, J. C. Shen, and P. K. Chu, “Mn2+-bonded reduced graphene oxide with strong radiative recombination in broad visible range caused by resonant energy transfer,” Nano Lett.11(9), 3951–3956 (2011).
[CrossRef] [PubMed]

Y. T. Liang, B. K. Vijayan, K. A. Gray, and M. C. Hersam, “Minimizing graphene defects enhances titania nanocomposite-based photocatalytic reduction of CO2 for improved solar fuel production,” Nano Lett.11(7), 2865–2870 (2011).
[CrossRef] [PubMed]

J. Hensel, G. Wang, Y. Li, and J. Z. Zhang, “Synergistic effect of CdSe quantum dot sensitization and nitrogen doping of TiO2 nanostructures for photoelectrochemical solar hydrogen generation,” Nano Lett.10(2), 478–483 (2010).
[CrossRef] [PubMed]

Nano Res

X. Sun, Z. Liu, K. Welsher, J. T. Robinson, A. Goodwin, S. Zaric, and H. Dai, “Nano-graphene oxide for cellular imaging and drug delivery,” Nano Res1(3), 203–212 (2008).
[CrossRef] [PubMed]

Nat. Chem.

K. P. Loh, Q. Bao, G. Eda, and M. Chhowalla, “Graphene oxide as a chemically tunable platform for optical applications,” Nat. Chem.2(12), 1015–1024 (2010).
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A. Bagri, C. Mattevi, M. Acik, Y. J. Chabal, M. Chhowalla, and V. B. Shenoy, “Structural evolution during the reduction of chemically derived graphene oxide,” Nat. Chem.2(7), 581–587 (2010).
[CrossRef] [PubMed]

Nature

V. I. Klimov, S. A. Ivanov, J. Nanda, M. Achermann, I. Bezel, J. A. McGuire, and A. Piryatinski, “Single-exciton optical gain in semiconductor nanocrystals,” Nature447(7143), 441–446 (2007).
[CrossRef] [PubMed]

Science

X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, and H. Dai, “N-doping of graphene through electrothermal reactions with ammonia,” Science324(5928), 768–771 (2009).
[CrossRef] [PubMed]

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Figures (4)

Fig. 1
Fig. 1

Transmission electron microscopy images of the (a) rGO/TiO2 and (b) GO/TiO2 hybrid spheres.

Fig. 2
Fig. 2

PL spectra of the TiO2 (blue), rGO/TiO2 (red), and GO/TiO2 (black) samples excited at (a) 266 nm and (b) 400 nm, respectively. The inset of (b) shows the PL spectrum of as-synthesized GO nanosheets measured with the 400 nm excitation.

Fig. 3
Fig. 3

PL decay curves of the TiO2 (blue), rGO/TiO2 (red), and GO/TiO2 (black) samples measured with the 400 nm excitation and plotted at the 0-3 ns range on a linear scale. Inset: The same PL decay curves plotted from 0 to 12 ns on a logarithmic scale. The fluorescence signal was collected over the entire spectrum of each sample for the PL decay measurement. IRF: instrument response function.

Fig. 4
Fig. 4

A schematic diagram of the energy levels for TiO2 and the localized sp2 domains of GO with respect to the water reduction and oxidation potentials. The water oxidation potential was set at 0 eV for convenience. The dotted arrow line (red) marks the IOT discussed in the text.

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