MIL-125(Ti)-derived double vacancy-induced enhanced visible-light-driven TiO2 p-n homojunction for photocatalytic elimination of OFL and Cr(VI)

The efficient removal of quinolone antibiotics and heavy metal ions Cr(VI) using photocatalysis has attracted increasing attention in the field of environmental remediation. Here, we create a porous TiO2 p-n junction featuring titanium vacancies and oxygen vacancies. The double-deficient TiO2 p-n junction has the same catalytic ability as P25 under UV light. Still, it also can produce copious radicals under visible light excitation to achieve oxidative degradation of ofloxacin and reduced Cr (VI). This is helped by the two reaction centers generated by oxygen and titanium vacancies, the effective light-trapping capacity, and the close interfacial contacts. By adjusting the calcination temperature, oxygen vacancy, and titanium vacancy concentrations, TiO2 p-n junctions with the best photocatalytic activity were produced. In the pH range of 3.63–9.65, TiO2 p-n junctions maintained outstanding activity. The degradation pathway of ofloxacin was examined using theoretical calculations and LC-MS. This study provides a technically guided experimental basis for preparing photocatalytic materials with double-defective p-n junctions.