Construction of double S-scheme heterojunctions CeO2/BHN/I--BiOIO3 for enhanced photocatalytic degradation of norfloxacin

In this study, double S-scheme heterojunctions were constructed by a simple hydrothermal and calcination method, accompanied by the special layered structure of BiOIO3 employed for its I- modification. This resulted in the formation of CeO2/[Bi6O6(OH)3](NO3)3·1.5H2O (BHN)/I--BiOIO3, which possesses double S-scheme heterojunctions. The improvement of photocatalytic degradation efficiency is derived from the result of the synergistic effect of double S-scheme heterojunctions and I- modification. In photocatalytic degradation experiment with norfloxacin as the target pollutant, the degradation efficiency of typical sample (CeO2/BHN/I--BiOIO3-2) reaches 97.50%, which is 9 times and 1.6 times than that of pure CeO2 and BHN/BiOIO3, respectively. Obviously, the CeO2/BHN/I--BiOIO3 double S-scheme heterojunctions significantly enhances its photocatalytic degradation ability of antibiotics in comparison to single-substance photocatalysts and simple two-phase composite. It is noteworthy that the CeO2/BHN/I--BiOIO3 double S-scheme heterojunctions are also capable of achieving a degradation rate of up to 70% for norfloxacin in river water. Furthermore, this double S-scheme heterojunctions demonstrate the degradation efficiencies of approximately 90% for quinolone antibiotics, including ofloxacin, enrofloxacin, ciprofloxacin, and norfloxacin. This research offers a novel approach to enhance the photocatalytic degradation of organic pollutants through double S-scheme heterojunctions and elemental modification.