A novel microwave-assisted impregnation method with water as the dispersion medium to synthesize modified g-C3N4/TiO2 heterojunction photocatalysts

Abstract

A microwave-assisted impregnation method with water as the dispersion medium was developed to prepare KCNN (K doped g-C 3 N 4 nanosheets)-TiO 2 heterojunction composite material (KCNNT). With this novel method, KCNN and TiO 2 can be evenly dispersed during synthesis to make large number of effective heterojunctions, thus offering high photocatalytic efficiency. Moreover, the use of water, instead of chemical reagents, as the dispersant makes this method both cost- and environmental-friendly. The photocatalytic degradation efficiency of RhB by KCNNT M synthesized by the microwave-assisted impregnation method was 1.23 times higher than that of KCNNT H synthesized by the thermal radiation assisted impregnation method. In addition, the photocatalytic degradation efficiency of RhB by the KCNNT 0.5M (formed with the KCNN and TiO 2 at ratio of 1:0.5) was 2.4 times higher than that of the CNT 0.5M (formed with pure g-C 3 N 4 and TiO 2 at ratio of 1:0.5), indicating the importance of modification of g-C 3 N 4 before the formation of composite materials. KCNN formed Z-type heterojunction with TiO 2 , which improved the separation efficiency of electron-hole and greatly improved the photocatalytic efficiency. The photocatalytic degradation efficiency of RhB by the KCNNT 0.5M was 4.1 times higher than that of pure g-C 3 N 4 under visible light. • The dispersant use of water, instead of chemical reagents makes this method both cost- and environmental-friendly. • The enhanced photocatalytic mechanism is a Z-scheme charge transfer pathway. • Indicating the importance of modification of g-C3N4 before the formation of composite materials. • The promising nanomaterials can be used for removal of dye pollutants.