Constructing TiO2@MOF S-scheme heterojunctions for enhanced photocatalytic degradation of antibiotics and Cr(vi) photoreduction

The residue of antibiotics and various pollutants has led to an urgent issue in environmental pollution control. In this study, we constructed an S-scheme P-TiO₂@Zn-MOF heterojunction by self-assembling phosphonate-based MOFs on mesoporous phosphate-TiO₂ beads. Compared to monomers, the P-TiO₂@Zn-MOF_2.0 heterojunction exhibits significantly higher photocatalytic activity for the photo-oxidative degradation of ciprofloxacin (97.2% in 60 min) and tetracyclic (TC) (94.5% in 100 min) and the photo-reduction of Cr(VI) (92.7% in 60 min) under simulated sunlight. Experimental results and calculations revealed the effective separation and transfer of photogenerated carriers at the P-TiO₂@Zn-MOF_2.0 S-scheme heterojunction interface, enabling the formation of highly active superoxide and hydroxyl radicals. Furthermore, the hybrid maintained excellent Cr(VI) photoreduction performance after recycling tests in actual electroplating industry wastewater at a strongly acidic pH.