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pH Dependent Optical Switching and Fluorescence Modulation of Molybdenum Sulfide Quantum Dots

Mishra, Himanshu and Umrao, Sima and Singh, Jai and Srivastava, Rajesh Kumar and Ali, Rashid and Misra, Arvind and Srivastava, Anchal (2017) pH Dependent Optical Switching and Fluorescence Modulation of Molybdenum Sulfide Quantum Dots. In: ADVANCED OPTICAL MATERIALS, 5 (9).

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Official URL: http://dx.doi.org/10.1002/adom.201601021


Investigations on fluorescent molecules with fluorescence switching behavior as function of pH, temperature, ion concentration, etc. is highly desirable in the field of sensor device fabrication. In this study, the authors report an easy and eco-friendly hydrothermal route for the synthesis of pH dependent fluorescent MoS2 quantum dots (MoS2-QDs). The average size of the synthesized QDs is found to be approximate to 7 nm which was confirmed with transmission electron microscopy and atomic force microscopy. These MoS2-QDs show the pH dependent fluorescence switching behavior. Under pH approximate to 1 the fluorescence intensity of the MoS2-QDs is quenched while it shows approximate to 200 times enhancement under pH approximate to 13. This florescence ON/OFF switching is mainly due to the surface adsorbed functional groups (NH2, SO42-, OH-, etc.) and is a combined effect viz. protonation-deprotonation process, acid etching, quantum confined Stark effect and particle agglomeration. A plausible mechanism for this pH dependent ON/OFF switching behavior is also discussed in this study. The band gap calculation under different pH environment is also in good agreement to the hypothesis.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the WILEY-V C H VERLAG GMBH, POSTFACH 101161, 69451 WEINHEIM, GERMANY
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Depositing User: Id for Latest eprints
Date Deposited: 03 Jun 2017 09:34
Last Modified: 03 Jun 2017 09:34
URI: http://eprints.iisc.ac.in/id/eprint/57089

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