Facile construction of p–n heterojunction Bi2O3/BNNS for synergistic tetracycline removal through adsorption–photocatalysis

Abstract

Herein, porous boron nitride nanosheets (BNNS) exhibiting n-type semiconductor characteristics were synthesized via high-temperature pyrolysis. Subsequently, a series of Bi₂O₃/BNNS composites with superior photocatalytic activity were constructed using a solvothermal method. Experimental results demonstrate that the optimized composite photocatalyst exhibits significantly enhanced adsorption capacity and photocatalytic activity compared to pristine BNNS and Bi₂O₃. The optimal Bi₂O₃/BNNS composite achieved degradation efficiencies of 94.65%, 94.23%, and 93.97% for tetracycline (TC), oxytetracycline (OTC), and doxycycline (DC) (each at 50 mg L⁻¹), respectively, under simulated solar irradiation. This study highlights that the exceptional adsorption capability of BNNS enables the Bi₂O₃/BNNS composite to fulfill the requirements for synergistic adsorption–photocatalysis. Furthermore, BNNS serves as an effective growth substrate, significantly regulating the growth of Bi₂O₃ nanowires and suppressing their agglomeration, thereby endowing the composite with a large specific surface area and pore volume. The formation of a p–n heterojunction also effectively suppresses the recombination of photogenerated charge carriers within the catalyst. Finally, this work elucidates the detailed process and underlying mechanism of photocatalytic tetracycline degradation driven by simulated sunlight. In summary, this study innovatively employs the Bi₂O₃/BNNS composite as a novel photocatalyst for tetracycline degradation and provides theoretical guidance for the design of advanced photocatalysts.