期刊
ACS SUSTAINABLE CHEMISTRY & ENGINEERING
卷 3, 期 10, 页码 2405-2413出版社
AMER CHEMICAL SOC
DOI: 10.1021/acssuschemeng.5b00771
关键词
Graphene quantum dots; Heterojunctions; Photocatalysis
资金
- National Natural Science Foundation of China [11174194, 91233102]
- Innovation Program of Shanghai Municipal Education Commission [13YZ017]
- Program for Changjiang Scholars and Innovative Research Team in University [IRT13078]
- China Postdoctoral Science Foundation [2012M520874]
- Shanghai Postdoctoral Scientific Program [13R21413100]
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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