Enhanced photocatalytic activity via dual Z-scheme charge separation in BiOBr/BiOCl/Bi2O2CO3 ternary heterojunction for organic contaminant removal

Bismuth-based photocatalysts including BiOBr, BiOCl, and Bi 2 O 2 CO 3 have been widely studied for their unique layered structures and optoelectronic properties. However, BiOCl and Bi 2 O 2 CO 3 have poor visible-light absorption, while BiOBr has rapid photogenerated charge recombination. These limitations hinder their practical application. To address this, ternary BiOBr/BiOCl/Bi 2 O 2 CO 3 (BCCO) heterostructures with adjustable molar ratios were prepared via a solvothermal method, targeting improved charge separation and light utilization. The structural, compositional, microstructural, optical and electrical properties were systematically characterized. The BCCO 0.2 composite (1:1:0.2 molar ratio) demonstrated remarkable photocatalytic activity, achieving 99.56 % degradation efficiency for Rhodamine B (RhB) within 50 min of xenon lamp irradiation. This efficiency was 1.18-, 1.31-, and 1.83-fold higher than that of the single-components BiOBr, BiOCl, and Bi 2 O 2 CO 3 , respectively. Furthermore, this heterostructure showed excellent operational stability and wide applicability. Mechanistic studies via radical trapping and band structure analysis revealed dual Z-scheme charge transfer in the heterojunction, enabling efficient electron-hole separation and expanded visible-light response. This work offers new insights for designing efficient bismuth-based photocatalysts for water remediation. • Ternary heterojunction BiOBr/BiOCl/Bi 2 O 2 CO 3 prepared via solvothermal method. • BCCO 0.2 shows enhanced photocatalysis activities with good stability. • The influencing factors of photocatalytic performance have been studied. • Dual Z-scheme boosts activity via light absorption & charge transport.