Ultrathin MoS2 nanosheet as co-catalyst coupling on graphitic g-C3N4 in suspension system for boosting photocatalytic activity under visible-light irradiation

Abstract

In this study, ultrathin molybdenum disulfide (MoS2) nanosheets with thickness of 1.6–8.8 nm were obtained by liquid-phase exfoliating bulk MoS2. Then, they were employed as cocatalyst to build ultrathin MoS2/g-C3N4 heterojunction by self-assembly method. The degradation reaction of chlorimuron-methyl herbicide and tetracycline antibiotics under visible light was used to evaluate the photocatalytic properties of ultrathin MoS2/g-C3N4. The results showed that ultrathin MoS2/g-C3N4 composite exhibit superior photocatalytic performance. The MoS2/g-C3N4 composite with 15 wt% of ultrathin MoS2 nanosheet exhibited the highest degradation efficiency with 90.4% for chlorimuron-ethyl and 91.7% for tetracycline in 45 min under simulated sunlight, which was 8.8 times and 13.4 times than that of bare g-C3N4, respectively. The outstanding photocatalytic activity of ultrathin MoS2/g-C3N4 heterojunction thanks to the unique features of ultrathin MoS2 nanosheet that it harvesting the entire visible light, increasing the contact surface area with the support and shortened the electron and ion migration length, as well as more exposed edge sulfur atoms as redox centers. The radical scavenger experiments showed that •OH and •O2- plays a key role in the photocatalytic degradation process. This study provides a new idea for the design of high-activity a co-catalyst, that is, ultrathin MoS2 nanosheet has a significant influence on the photocatalytic performance of MoS2/g-C3N4 heterostructure photocatalyst.