Enhanced tetracycline degradation and electricity generation by persulfate in a photocatalytic fuel cell with a ternary Z-scheme photoanode

Abstract

The practical application of a photocatalytic fuel cell (PFC) is usually limited by its long pollutant degradation period. Here, two strategies were adopted to improve the PFC performance. On one hand, a ternary Z-scheme heterojunction photocatalyst (Bi₂O₄/Bi₂WO₆/C₃N₄qds) was used as the photoanode to promote the separation of photo-generated charge carriers, thereby improving the photocatalytic process. On the other hand, CuFe₂O₄ was used as the photocathode to activate persulfate (PS) to further enhance pollutant degradation and electricity generation. The results indicated that, under visible light irradiation (45 min), the degradation efficiency of tetracycline by the coupling system of Bi₂O₄/Bi₂WO₆/C₃N₄qds-CuFe₂O₄ + PS (PFCps) reached to 94.5%. The corresponding first-order kinetic constant was 8.13, 3.40, 3.34, and 1.89 times that of PS, Bi₂O₄/Bi₂WO₆/C₃N₄qds + PS, CuFe₂O₄ + PS, and Bi₂O₄/Bi₂WO₆/C₃N₄qds-CuFe₂O₄, respectively. The highest maximum power density of the PFCps system was 37.0 μW·cm⁻², which was 1.89 times that of the PFC of Bi₂O₄/Bi₂WO₆/C₃N₄qds-CuFe₂O₄. The reactive species capturing experiments verified that ·OH, ·O₂^-, h⁺, and ·SO₄^- had positive effects on the tetracycline degradation. In addition, the mechanism involved in the PFCps system was proposed. This work provided a novel idea for the development of coupling technologies to treat antibiotic wastewater.