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

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. •PPy nanoparticles are in-situ synthesized on Bi2MoO6 hollow microsphere.•PPy nanoparticles induced rapid separation of photo-generated electron-hole pairs.•Bi2MoO6/PPy photocatalysts obtain perfect photocatalytic activity and photostability.•The degradation pathways of MB and TC are revealed by deep analysis of intermediates.