Rationally designed C-PANI/BiOBr STEP-scheme heterojunction photocatalyst for boosting photodegradation of 17β-estradiol

Abstract

17β-estradiol (E2) in natural water has caused serious environmental problems because of its extremely high estrogenic activity. Herein, a novel β-CD@PANI/BiOBr (C-PANI/BiOBr) step scheme (S-scheme) heterojunction photocatalyst was successfully prepared via facile chemical precipitation method. The encapsulation of β-cyclodextrin (β-CD) around polyaniline (PANI) contributed to better transfer of photogenerated carries by the stabilization of radical cation and excellent adsorption capability driven by hydrophobic interaction, hydrogen bonding and π-π stacking. The C-PANI/BiOBr heterojunction photocatalysts realized excellent light absorption in full spectrum. The N derived from C-PANI could coordinate with Bi metal ions, which favored forming BiOBr with (110) facet exposure, thus promoting the photogenerated electron-hole separation. The optimal 20% C-PANI/BiOBr achieved rapid degradation of contaminants (100% removal of E2 in 40 min and RhB in 9 min) under visible light irradiation. Furthermore, three main degradation pathways of E2 photodegradation were proposed by high performance liquid chromatography-mass spectrometer (HPLC-MS) results, and the toxicity of E2 and intermediates were evaluated by ECOSAR program. The active species capture experiment indicated that h+ and •O2– played the dominated roles in the photodegradation process and S-scheme mechanism of C-PANI/BiOBr with enhanced photocatalytic performance was also revealed. This study provided an insight in fabricating efficient photocatalysts for environmental remediation.