Synthesis and characterization of TiO2/ZnCr2O4 core-shell structure and its photocatalytic and antibacterial activity

Abstract

A shell of ZnCr2O4 spinel was facilely covered on the surface of TiO2 nanoparticles to synthesize TiO2/ZnCr2O4 core-shell structure using TiO2 seed particles and heterogeneous precipitation. The as-prepared nanocomposite was characterized in terms of crystal structure, morphology and surface area, light absorption and band gap. After coupling TiO2 with ZnCr2O4, a heterojunction formed between the two semiconductor materials. UV–vis absorption spectra showed a red shift of the absorption edges and lower band gap of 3.0 eV for the composite system compared to the single phase TiO2 (3.4 eV) due to the formation of new energy level at the core-shell interface. Photocatalytic activity of the nanocomposites was evaluated by degradation of methylene blue under UV-light irradiation, revealing that the core-shell nanocomposite exhibits superior photocatalytic activity (99% yield) compared to the single phase TiO2 (40% yield) even after 4 consecutive reaction runs. In fact, this enhancement was attributed to the efficient separation and migration of the photogenerated electron–hole pairs at the core-shell interface due to the formation of energy bands heterojunction at the interface. Also, it was found that the synthesized core-shell structure is a highly effective antibacterial material against E. coli bacteria.