Reactable ionic liquid assisted synthesis of Pd modified BiOBr flower-like microsphere with high dispersion and their enhanced photocatalytic performances

Abstract

Pd modified BiOBr flower-like microspheres have been synthesised via a facile one-pot ethylene glycol assisted solvothermal process in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br). The as prepared samples were characterised by multiple techniques to investigate the structure, morphology and photocatalytic properties. Ionic liquid [C16mim]Br was introduced to improve the dispersity of Pd nanoparticles, so as to construct the tight junctions between Pd nanoparticles and BiOBr. The Pd nanoparticles could distribute uniformly on the surface of BiOBr. The photocatalytic abilities of the as prepared photocatalysts were evaluated using rhodamine B (RhB) and ciprofloxacin as target pollutants. After the introduction of Pd, the photocatalytic activities of Pd/BiOBr composites have been enhanced under visible light irradiation. The 0·5 wt-% Pd/BiOBr possessed the optimal photocatalytic activity, which was about 6·6 times higher than pure BiOBr for the degradation of RhB. The results of diffuse reflectance spectroscopy, photoluminescence, photocurrent and electrochemical impedance spectroscopy demonstrated the enhanced photocatalytic performance could be attributed to the introduction of Pd, which improves the separation efficiency of the photogenerated electrons and holes. The trapping experiments of radicals indicated that hole was the main reactive species for the photocatalytic degradation of RhB. A possible photocatalytic mechanism was proposed that the Pd nanoparticles promote charge transfer, and inhibit the recombination probability of the photogenerated electrons and holes, which is beneficial for improving the photocatalytic performance of BiOBr.