Promoting the photocatalytic capacity of Type I heterojunction (Bi12O17Cl2/Sb2O3) by incorporating MWCNTs for boosted carbamazepine degradation mechanism

Abstract

The photocatalytic heterojunctions is considered a suitable methodology to enhance photoactivity by boosting visible light harvesting and hampering charge recombination. Herein, bismuth oxychloride Bi₁₂O₁₇Cl₂ nanosheets and pyramidal Sb₂O₃ heterogeneous junctions were built via the solvothermal method and assembled with multi-wall carbon nanotubes (MWCNTs). Compared with single photocatalysts, the absorption ability of Bi₁₂O₁₇Cl₂/Sb₂O₃/MWCNT was meaningfully enhanced due to the MWCNT's ability to modify the electronic structure of Bi₁₂O₁₇Cl₂/Sb₂O₃, decreasing the bandgap value and increasing the visible light response. The morphological tests presented a ternary hybrid with pyramidal Sb₂O₃ particles anchored on Bi₁₂O₁₇Cl₂ nanosheets interconnected with MWCNT nanotubes, forming the Bi₁₂O₁₇Cl₂/Sb₂O₃/MWCNT network with abundant active sites. Under simulated solar energy, the Bi₁₂O₁₇Cl₂/Sb₂O₃/MWCNT hybrid photocatalyst exhibited the highest carbamazepine (CBZ) drug photodegradation activity (90.2 % within 75 min). These results confirm a suitable Type I heterojunction between Bi₁₂O₁₇Cl₂ and Sb₂O₃ assisted by MWCNT, allowing a speedy transfer of photo-charges at the interface between Bi₁₂O₁₇Cl₂ and Sb₂O₃. A reaction mechanism is projected and deliberated via trapping tests, photoluminescence, and electrochemical tests. This work may introduce important concepts to enhance the weak heterojunction systems (Type I and Type II) by integrating with effective charge mediators (like MWCNT), achieving competing catalytic characteristics with Z-type or S-scheme mechanisms.