Dual Z-scheme Bi3TaO7/Bi2S3/SnS2 photocatalyst with high performance for Cr(VI) reduction and TC degradation under visible light irradiation

Ternary direct dual Z-scheme Bi 3 TaO 7 /Bi 2 S 3 /SnS 2 photocatalyst was successfully prepared by hydrothermal method. The composite photocatalysts exhibited high photocatalytic performance on both Cr(VI) reduction and tetracycline (TC) degradation under the irradiation of visible light. The results manifested that the photogenerated charge transfer efficiency was improved after forming the dual Z-scheme heterojunction. As a result, the composite catalysts exhibited higher photocatalytic degradation efficiency than the corresponding single samples. The apparent rate constant ( k ) value of the best sample BBS-3 for TC degradation was 0.0403 min −1 , which was 40 times, 8 times, and 18 times higher than that of single samples. While the k value of BBS-3 for the Cr(VI) reduction was 0.0249 min −1 , it was about 23 times, 7 times, and 18 times that of single catalysts. Recycle experiments indicated that the BBS-3 had good photocatalytic stability. Meanwhile, the possible mechanism on Cr(VI) reduction and TC degradation was proposed based on the experimental results. Graphical abstract