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Photocatalytic Decomposition Using Visible Light and Nanometer Crystals

Eliminating Toxic Pollutants Using Sunlight and Nanocrystals

Inverse micellar synthesis of semiconductor nanocrystals
inverse synthesis image
Mo4+ + 2S2- --> MoS2

We have demonstrated complete destruction of common toxic organic pollutants, including the ubiquitous pentachlorophenol (PCP), by photocatalytic decomposition using visible light and nanometer-size MoS2 crystals in solution as the photocatalyst. Direct photo decomposition of organic chemicals to benign carbon dioxide (CO2) and dilute mineral acids is feasible but had been impractical.

Chart comparing relative PCP to catalyst

The catalytic alternative to our approach uses TiO2 which requires ultraviolet (UV) light to generate the electrons needed for the decomposition reaction. UV light is expensive and impractical for large-scale cleanup. By using a unique inverse micellar process to synthesize MoS2 nanocrystals of specific sizes, we have systematically shifted the optical absorption from the infrared for bulk MoS2 (useless for the present application) to the visible region of the spectrum.

In addition, by tuning the light absorption by varying the nanocrystal size, we can tailor the decomposition ability of MoS2 to specific pollutants and accelerate the speed of the reaction. More importantly, exploiting this size-selective synthesis process will enable us to capitalize on a plentiful (visible) energy source — sunlight — to efficiently eliminate dangerous chlorinated organic and phenolic pollutants.

oxidation image

 

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