Surface engineering of copper sulfide-titania-graphitic carbon nitride ternary nanohybrid as an efficient visible-light photocatalyst for pollutant photodegradation.

Advanced photocatalyst is a key for photocatalytic water purification in the environmental pollutant remediation. In this study, graphitic carbon nitride (g-CN) modified by CuS and TiO2 ternary nanohybrid (CuS-TiO2-g-CN) with close interfacial contact among CuS, TiO2 and g-CN was fabricated through a facile and green method. Compared to the binary g-CN-based counterparts, the CuS-TiO2-g-CN possesses multiple photo-generated charge transfers owing to the synergistic action of CuS, TiO2 and g-CN. And hence the separation efficiency of photo-generated electron-hole pairs can be improved for the CuS-TiO2-g-CN. The optical and photoelectrochemical measurements prove that the CuS-TiO2-g-CN has narrower band gap energy and higher transient photocurrent density than those of g-CN and TiO2-g-CN. Therefore, the CuS-TiO2-g-CN shows notably higher photocatalytic activity and stability towards the degradation of Rhodamine B (RhB) than g-CN and TiO2-g-CN under visible-light irradiation. Moreover, a possible visible-light photocatalytic mechanism of CuS-TiO2-g-CN for degrading RhB was also proposed on the basis of the experimental results and literature reports.