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

To effectively degrade organic pollutants in wastewater, visible-light-driven BiMoO/PPy hierarchical heterogeneous photocatalysts were prepared through a solvothermal method and the following in-situ chemical oxidation polymerization. Compared with pristine BiMoO photocatalyst, the composite photocatalysts exhibited dramatically improved photocatalytic activity and photostability towards the degradation of methylene blue dye and tetracycline antibiotic. BiMoO/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 BiMoO 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 BiMoO semiconductor in nanoscale is an efficient approach to improve photocatalytic activity for environmental remediation.