CuBi2O4/BiOBr composites promoted PMS activation for the degradation of tetracycline: S-scheme mechanism boosted Cu2+/Cu+ cycle

The CuBi2O4/BiOBr S-scheme photocatalysts, combining 1D CuBi2O4 nanorods and 2D BiOBr nanosheets were successfully synthesized by a hydrothermal method to activate peroxymonosulfate (PMS) towards efficient tetracycline (TC) degradation. Benefiting from the construction of S-scheme heterojunction, the Cu2+/Cu+ cycle of CuBi2O4/BiOBr-50 (CBB-50) had been greatly boosted and further promoted the activation of PMS for TC degradation. Compared with bare CuBi2O4 and BiOBr, CBB-50 could degrade 90.3% of TC within 35 min, and the degradation kinetic rate was notably increased by 8.4 and 3.3 times, respectively. The results of the cycling degradation experiment indicated that the as-prepared CBB-50 retained 91.7% of the degradation ability, implying its excellent stability. Interestingly, compared with the harsh pH requirements of traditional Fenton reactions, CBB-50 could perform photocatalytic reactions in the pH range of 2.5-10.5 and maintain excellent TC degradation performance. The scavenging experiments implied that SO4.-/.OH/h(+)/.O-2(-)/O-1(2) were active species for the TC degradation. The XPS analysis, band structure and trapping results further verified that the transfer of photogenerated carriers conformed to the S-scheme mechanism. Considering its excellent performance, stability and applicability, CBB-50 would become a reliable candidate for the large-scale practical application of PMS activation in the degradation of antibiotics.