Photooxidation of Organic Chemicals Catalyzed by Nanoscale MoS₂

Abstract

We describe experiments that explore the use of nanosize MoS2 semiconductors for catalyzing the photooxidation of an organic chemical, phenol. The band gap of nanoscale MoS2 can be tuned across the visible spectrum and we show that d = 4.5 nm MoS2 which has an absorbance edge near 550 nm photooxidizes phenol using only visible light (>450 nm) while smaller band gap d = 8−10 nm MoS2 or wide band gap Degussa P-25 TiO2 do not. The possibility of increasing the rate of photooxidation of phenol by deposition of nanoclusters of MoS2 on bulk semiconductor powders is investigated. It is shown that small amounts (<5 wt %) of nanoscale MoS2 deposited onto TiO2 can lead to significant (∼2-fold) enhancements of phenol destruction rates compared to TiO2 by itself.