Semiconductor nanocrystal based visible light photocatalyst for organic dye degradation

Abstract

Environmental pollution caused by organic pollutants presents a severe ecological problem regarding the difficulty of degradation. Application of photocatalysis appears to be the most appealing and promising method for decomposition of toxic organic compounds. Titanium (TiO2) is the most widely explored photocatalytic material largely due to its low cost, high chemical stability and relatively high catalytic efficiency. However, TiO2 cannot be used for effective solar energy harvesting and conversions due to its large bandgap. Significant challenges remain in developing a visible light driven photocatalyst.

In this project, semiconductor nanocrystals CdS, CdSe, and CdSeS synthesized by hotinjection method were studied due to their tunable bandgap, and the absorption in the visible light range. CdS nanocrystal with bandgap of 2.68eV, absorption wavelength of 463nm was proved to be the most efficient photocatalyst among CdS, CdSeS, and CdSe for organic dye degradation. With the presence of Lactic Acid, CdS could successfully degraded 92% of Rhodamine B in 10 minutes which was significantly higher than the degradation rate of 30% with P25 TiO2 under the same condition.