The Se role as a mediator to enhance the photocatalytic performance of the ZnSe/g-C3N4 nanocomposites

ZnSe/g-C3N4 nanocomposites with different concentration of g-C3N4 (5%, 10%, and 15%) have been applied as the photocatalytic materials. The results indicated the more than 97% of dye molecules have been degraded by ZnSe/g-C3N4 (10%) nanocomposites. Study of the band structures has been indicated a type-II heterostructure has been formed by ZnSe and g-C3N4. The morphology of the ZnSe structures has been changed from nanorods (NRs) into nanoparticles (NPs) by g-C3N4. In addition, the X-ray diffraction (XRD) patterns of the ZnSe/g-C3N4 nanocomposites indicated a Se phase has been appeared in the patterns . In addition, the porosity concentration of the ZnSe/g-C3N4 nanocomposites has been increased by g-C3N4, which was a parameter to enhance the photocatalytic performance. Band structure of the nanocomposites indicated that, the external Se phase in the nanocomposites has a significant role to improve the photocatalytic activity. In fact, the recombination rate of the electron-hole pair (EHP) has been reduced due to the Se's conduction band (CB) position and caused the Se to play a mediator role during the photocatalytic activity. On the other hand, the oxidation reaction during the photocatalytic activity of the ZnSe/g-C3N4 nanocomposites has been carried by photogenerated holes of the Se.