Synthesis of Co3O4 coated on N,S doped TiO2 for novel photocatalytic degradation of toxic organic pollutant in aqueous environment

Herein, Co3O4 was coated on N,S co-doped TiO2 to synthesize Co3O4/N,S–TiO2 nanocomposites applying for an advanced degradation of Direct Blue 71 (DB 71) under visible irradiation. N and S were used to incorporate into TiO2 matrix to decrease its energy band gap (Ebg) while Co3O4 was used to coat on N,S–TiO2 to further enhance its electron-hole separation efficiency. Therefore, these synthesized Co3O4/N,S–TiO2 exhibited novel photocatalytic ability efficiently degrading DB 71. The optimal Co3O4 coating ratio for maximum improving photocatalytic degradation ability of the N,S–TiO2 was 30 wt %. Above the optimal coating content, the excess Co3O4 would cover more N,S–TiO2 surface or prevent the contact of incident light to these particles resulting in decrease in the photocatalytic performance. The pH for zero point charge of the Co3O4/N,S–TiO2 was approximately 4.7 while the DB 71, which has negative charge sulfuric groups, favors to adsorb on positive surface. Thus, optimal pH for efficient decomposition of DB 71 by the Co3O4/N,S–TiO2 was 4. Finally, the study investigated that the sunlight was perfectively suitable source to excite for photocatalytic degradation of DB 71 by the synthesized Co3O4/N,S–TiO2.