Hierarchical Bi2MoO6 microsphere photocatalysts modified with polypyrrole conjugated polymer for efficient decontamination of organic pollutants

Abstract

To effectively degrade organic pollutants in wastewater, visible-light-driven Bi₂MoO₆/PPy hierarchical heterogeneous photocatalysts were prepared through a solvothermal method and the following in-situ chemical oxidation polymerization. Compared with pristine Bi₂MoO₆ photocatalyst, the composite photocatalysts exhibited dramatically improved photocatalytic activity and photostability towards the degradation of methylene blue dye and tetracycline antibiotic. Bi₂MoO₆/PPy-80 sample achieved the highest photocatalytic degradation rates for methylene blue dye (93.6%) and tetracycline antibiotic (88.3%) under visible light irradiation. These two organic pollutants could be completely degraded into nontoxic small molecules according to in-depth HPLC-MS analysis of degradation products. The transient photocurrent responses, electrochemical impedance spectra, and photoluminescence spectra demonstrated that the introduction of PPy nanoparticles on the surface of Bi₂MoO₆ nanosheets could effectively accelerate the separation of photo-generated electron-hole pairs. Furthermore, a possible synergetic photocatalytic mechanism was put forward based on the electron spin resonance and XPS valence-band spectra. This work indicated that construction of hierarchical composite photocatalysts combining polypyrrole conductive polymer and Bi₂MoO₆ semiconductor in nanoscale is an efficient approach to improve photocatalytic activity for environmental remediation.

Keywords: Conductive polymer; Environmental remediation; Heterogeneous photocatalysts; Photocatalytic degradation.