Article

Rapid water disinfection using vertically aligned MoS2 nanofilms and visible light

  • Nature Nanotechnology 11, 10981104 (2016)
  • doi:10.1038/nnano.2016.138
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Abstract

Solar energy is readily available in most climates and can be used for water purification. However, solar disinfection of drinking water mostly relies on ultraviolet light, which represents only 4% of the total solar energy, and this leads to a slow treatment speed. Therefore, the development of new materials that can harvest visible light for water disinfection, and so speed up solar water purification, is highly desirable. Here we show that few-layered vertically aligned MoS2 (FLV-MoS2) films can be used to harvest the whole spectrum of visible light (50% of solar energy) and achieve highly efficient water disinfection. The bandgap of MoS2 was increased from 1.3 to 1.55 eV by decreasing the domain size, which allowed the FLV-MoS2 to generate reactive oxygen species (ROS) for bacterial inactivation in the water. The FLV-MoS2 showed a 15 times better log inactivation efficiency of the indicator bacteria compared with that of bulk MoS2, and a much faster inactivation of bacteria under both visible light and sunlight illumination compared with the widely used TiO2. Moreover, by using a 5 nm copper film on top of the FLV-MoS2 as a catalyst to facilitate electron–hole pair separation and promote the generation of ROS, the disinfection rate was increased a further sixfold. With our approach, we achieved water disinfection of >99.999% inactivation of bacteria in 20 min with a small amount of material (1.6 mg l–1) under simulated visible light.

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Acknowledgements

We acknowledge the Stanford facilities, Stanford Nanocharacterization Laboratory and Soft & Hybrid Materials, for characterization. Y.C. acknowledges support from the US Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division, under contract DE-AC02-76SF00515. We thank G. M. Stewart for his help with the schematic drawing.

Author information

Affiliations

  1. Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA

    • Chong Liu
    • , Desheng Kong
    • , Po-Chun Hsu
    • , Hongtao Yuan
    • , Hyun-Wook Lee
    • , Yayuan Liu
    • , Kai Yan
    • , Dingchang Lin
    •  & Yi Cui
  2. Department of Applied Physics, Stanford University, Stanford, California 94305, USA

    • Haotian Wang
  3. Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA

    • Shuang Wang
  4. Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, USA

    • Peter A. Maraccini
    • , Kimberly M. Parker
    •  & Alexandria B. Boehm
  5. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94305, USA

    • Yi Cui

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Contributions

C.L. and Y.C. developed the concept. C.L. synthesized the samples and conducted the disinfection measurement and material characterizations. D.K. and H.W. helped with the material synthesis. P.-C.H. and S.W. helped with the optical measurement. H.Y. helped with the Kelvin probe measurement. H.-W.L. did the TEM characterization. D.K. helped with the Raman spectroscopy measurement. Y.L. helped with catalyst measurements. P.A.M. helped with estimation of the real-sunlight spectrum. K.M.P. helped with HPLC measurement. C.L., A.B.B. and Y.C. analysed the data and co-wrote the paper. K.Y. and D.L. provided important experimental insights. All the authors discussed the whole paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Yi Cui.

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