Cobalt oxide/copper bismuth oxide/samarium vanadate (CoO/CuBiO/SmVO) dual Z-scheme heterostructured photocatalyst with high charge-transfer efficiency: Enhanced carbamazepine degradation under visible light irradiation.

Herein, a dual Z-scheme heterojunction photocatalyst consisting of CoO, CuBiO, and SmVO for carbamazepine (CBZ) degradation was synthesised and characterised by XRD, FTIR, UV-Vis DRS, XPS, FE-SEM, and TEM. The reduction in electron-hole recombination was evaluated by PL, LSV, and EIS analysis. The heterojunction, CoO/CuBiO/SmVO (CCBSV) showed enhanced photocatalytic activity of 76.1% ± 3.81 CBZ degradation under visible light irradiation, ascribed to the improved interfacial contact, visible light capturing ability, and enhanced electron-hole separation and transportation through the formation of Z-scheme heterojunction. The formation of dual Z-scheme was confirmed by active radical experiments and XPS analysis that helped to prose the mechanism of degradation. The catalyst showed sustained stability after 4 cycles of reuse. Ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) was employed to identify the degradation by-products of CBZ, and a possible mechanistic degradation pathway was proposed. This study provided an insight into the development of efficient dual Z-scheme heterojunction photocatalyst for remediation of CBZ which can be extended to other organic pollutants.