Photocatalytic degradation of Direct Red 80 using ZnO/ZnTiO3/Zn2Ti3O8 ternary nanocomposite

In the present study, novel zinc titanate-based nanocomposites were synthesized via an one-step sol-gel process. The crystalline structural, morphological and optical properties of the samples were characterized. Effect of Ti:Zn molar ratio on the structures and crystalline phase of the composites was investigated. ZnO/ZnTiO3/Zn2Ti3O8 ternary heterojunction catalyst obtained by Ti:Zn molar ratio of 1:1. The photocatalytic activity of the prepared nanocomposites with various Ti:Zn molar ratio was investigated for Direct Red 80 (DR80) degradation in aqueous solution. Excellent photocatalytic activity of ZnO/ZnTiO3/Zn2Ti3O8 nanocomposite exhibited 93.6% degradation of DR80 after 90 min irradiation which is 1.24 times of DR80 degradation using ZnO nanoparticles. The enhanced photocatalytic performance could be attributed to the formation of ZnTiO3 as dominant phase and the heterojunction of electrons among ZnTiO3, Zn2Ti3O8 and ZnO, which enabled electron transfer in the nanocomposite, suppressed electron-hole pair recombination, and encouraged a wider light absorption by photocatalyst. The effect of main operating conditions on the photocatalytic degradation of dye was investigated using ZnO/ZnTiO3/Zn2Ti3O8 nanocomposite and optimum conditions were determined for degradation. The stability and cyclic efficiency of ZnO/ZnTiO3/Zn2Ti3O8 photocatalyst were investigated. Finally, the kinetic studies revealed the photocatalytic degradation kinetics of DR80 would follow a pseudo-second-order reaction.