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Water-Soluble, single-crystalline, and amine-functionalized graphene quantum dots (GQDs) with absorption edge at similar to 490 nm were synthesized by a molecular fusion method, and stably deposited onto anatase TiO2 nanoparticles under hydrothermal conditions. The effective incorporation of the GQDs extends the light absorption of the TiO2 nanoparticles from UV to a wide visible region. Moreover, amine-functionalized GQD-TiO2 heterojunctions can absorb more 02 than pure TiO2, which can generate more center dot O-2 species for MO degradation. Accordingly, the heterojunctions exhibit much higher photocatalytic performance for degrading methyl orange (MO) under visible-light irradiation than TiO2 alone. At optimum GQD content (1.0 wt %), an apparent MO decomposition rate constant is 15 times higher than that of TiO2 alone, and photocurrent intensity in response to visible-light excitation increases by 9 times. Compared with conventional sensitization by toxic, photounstable quantum dots such as CdSe QDs, the sensitization by environmentally friendly GQDs shows higher visible-light photocatalytic activity and higher cycling stability. Monodispersed QD-based heterojunctions can effectively inhibit the fast recombination of electron hole pairs of GQDs with a large exciton binding energy. The photogenerated electron transfer, energy-band-matching mechanism of GQD/TiO2, and possible MO decomposition pathways under visible-light irradiation are proposed.
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ACS SUSTAINABLE CHEMISTRY & ENGINEERING
ISSN: 2168-0485
Year: 2015
Issue: 10
Volume: 3
Page: 2405-2413
5 . 2 6 7
JCR@2015
7 . 1 0 0
JCR@2023
JCR Journal Grade:1
CAS Journal Grade:1
Cited Count:
WoS CC Cited Count: 251
SCOPUS Cited Count: 267
ESI Highly Cited Papers on the List: 0 Unfold All
WanFang Cited Count:
Chinese Cited Count:
30 Days PV: 2
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