Construction of 2D/2D g-C 3 N 4 @Bi m+1 Fe m-3 Ti 3 O 3m+3 (m = 4, 5, 6) S-scheme heterojunctions for efficient photocatalytic tetracycline degradation

Aurivillius phases with narrow band gaps have attracted extensive interest in the field of photocatalysis, however, they exhibit poor activity due to the low utilization of photogenerated carriers. Herein, a series of S-scheme C3N4@Bi m+1 Fe m-3 Ti 3 O 3m+3 (m = 4, 5, 6) heterojunctions with two-dimensional structures were synthesized by simple two-step method. Compared with single materials, the composites exhibit excellent photocatalytic tetracycline degradation under visible light, and 91.8% of tetracycline can be degraded accompanied with 81.2% of TOC removal within 120 min over C 3 N 4 @Bi 5 FeTi 3 O 15 . The enhanced photocatalytic performance is due to strong interface interaction, high conductivity, and efficient charge separation ability. The mechanism analysis indicates that the C 3 N 4 @Bi 5 FeTi 3 O 15 heterojunction follows an S-scheme heterojunction mechanism with a strong interfacial internal electric field directed from C 3 N 4 to Bi 5 FeTi 3 O 15 , thus, the photogenerated electrons in Bi 5 FeTi 3 O 15 move toward C 3 N 4 , which retains high oxidation ability of Bi 5 FeTi 3 O 15 and high reduction ability of C 3 N 4 to efficiently produce the reactive species, such as O 2 − · and ·OH. Graphical Abstract