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

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 (Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds) was used as the photoanode to promote the separation of photo-generated charge carriers, thereby improving the photocatalytic process. On the other hand, CuFe 2 O 4 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 Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds-CuFe 2 O 4 + 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, Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds + PS, CuFe 2 O 4 + PS, and Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds-CuFe 2 O 4 , 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 Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds-CuFe 2 O 4. The reactive species capturing experiments verified that ·OH, ·O 2 -, h +, and ·SO 4 - 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. [Display omitted] • A ternary Z-scheme heterojunction was prepared by combining Bi 2 O 4 , Bi 2 WO 6 and C 3 N 4 qds • The Z-scheme photocatalyst promoted electron transfer from photoanode to photocathode • PS activation was facilitated in this Z-scheme PFC with CuFe 2 O 4 as photocathode • PFC+PS system simultaneously enhanced TC degradation and electricity generation • ·OH, ·O 2 -, h +, and ·SO 4 - had positive effects on TC degradation in the PFC+PS system [ABSTRACT FROM AUTHOR]