Dual NPN Bi2O3/BiOCl/Bi24O31Cl10 ternary heterojunction for the enhanced photocatalytic activities

Designing of an efficient heterojunction for the practical application of photocatalysis has been considered as the promising topic for the settle of the energy crisis and environmental pollution. Herein, a dual Bi 2 O 3 /BiOCl/Bi 24 O 31 Cl 10 ternary heterojunction has been constructed by the in-situ photoreduction technique for the photocatalytic degradation of rhodamine B (RhB) and tetracycline hydrochloride (TCH). The significant difference in the work function ( W f ) among Bi 2 O 3 , BiOCl, and Bi 24 O 31 Cl 10 leads to the formation of the space charge region (built-in electric field) around the heterojunction interface along with band bending, which facilitates the directional migration and spatial separation of photogenerated carriers and offers the strong redox capacity of photogenerated electrons and holes. This process is beneficial for the generation of active species of superoxide free radical ( ∙ O 2 − ) and the photo-generated hole (h + ). The optimized removal efficiencies of RhB and TCH for the ternary heterojunction were nearly 7.19 and 1.28 times higher than these for the pure Bi 24 O 31 Cl 10 , respectively. Furthermore, the involved vital reactive radicals, potential degradation pathway, and the eco-toxicity of intermediates over Bi 2 O 3 /BiOCl/Bi 24 O 31 Cl 10 are evaluated through the trapping experiment, LC-MS calculation, and toxicity analysis. This work demonstrates a new heterojunction photocatalyst for the elucidation of pollutant degradation mechanism.