Nanoarchitecturing TiO2/NiCr2O4 p-n heterojunction photocatalysts for visible-light-induced activation of persulfate to remove tetracycline hydrochloride

Herein, TiO2/NiCr2O4 nanocomposites with p-n heterojunctions were synthesized via a refluxing method and used with peroxydisulfate (PDS) to produce extensive reactive radicals. Textural, optical, photoelectrochemical, structural, and morphological properties of the prepared materials were extensively investigated. After adding 1.48 mM PDS, the removal rate constant of tetracycline hydrochloride (TH) over the TiO2/NiCr2O4 (20%)/PDS system was almost 20.5, 7.24, and 5.91-times as high as the pristine TiO2, TiO2/PDS, and TiO2/NiCr2O4 (20%) samples, respectively. Therefore, the synergistic effect of PDS and heterogeneous photocatalysis remarkably impacted the degradation reaction of TH. It was proposed that all h(+), O-center dot(2)-, (OH)-O-center dot, and SO4 center dot- contributed to the degradation reaction. According to the formation of heterojunction between n-TiO2, and p-NiCr2O4 semiconductors, a plausible mechanism for removal of different contaminants in the TiO2/NiCr2O4/PDS system was discussed.