Synthesis of Z-Scheme heterojunction ZnNb2O6/g-C3N4 nanocomposite as a high efficient photo-catalyst for the degradation of 2,4-DCP under simulated sunlight

Abstract

In view of the deterioration of the environment and the shortage of resources, it is necessary to develop efficient photocatalysts for the degradation of organic pollutants. Herein, a novel and environmentally friendly ZnNb2O6/g-C3N4 heterojunction nanocomposite was synthesized by calcination-hydrothermal method successfully. The chemical and physical capabilities of the material were characterized by various kinds of analytical instruments. Compared with ZnNb2O6 and g-C3N4, ZnNb2O6/g-C3N4 showed the strongest photocatalytic activity. The nanomaterial was used in the removal of the pollutant 2,4-DCP. The effects of degradation conditions were discussed including component ratio, material dosage, initial analyte concentration, pH and salinity. After 180 min’ simulated sunlight illumination, the removal efficiency of 2,4-DCP (10 mg/L) reached 95.7% under the optimum condition. Furthermore, the possible photocatalytic mechanisms were discussed according to four aspects: (i) The conformation of the active species; (ii) The calculation of valence and conduction band; (iii) The analysis Z-scheme heterojunction mechanism; (iv) The speculation of feasible photocatalytic paths. In conclusion, the ZnNb2O6/g-C3N4 (ZC-7) nanocomposite has the least recombination rate of electron-hole pairs and the highest photocatalytic efficiency.