Plasmon-mediated activation of persulfate for efficient photodegradation of ionic liquids over Ag@Pd core–shell nanocubes

Abstract In this study, we propose a novel photo-activation method to remove persistent organic pollutants through a SO4˙ˉ-based advanced oxidation process. Core–shell Ag@Pd nanocubes were prepared by a facile seed-mediated method and, afterward, explored for photodegradation of a representative ionic liquid (IL), [C4mim]Br. Electron paramagnetic resonance measurements and radical scavenging experiments demonstrated that the species mainly responsible for degrading [C4mim]Br were the radicals of SO4˙ˉ. The plasmon-mediated nature of the Ag@Pd catalysts was verified by their wavelength-dependent performance. Subsequent optical simulation indicated that, other than the plasmonic Ag core, the non-plasmonic Pd shell was the preferential site for dissipating the absorbed photons into energetic charge carriers to produce the radical species. Finally, based on the detected intermediates, we propose the degradation pathway of ILs in the plasmon-mediated process. The results of our method suggest favorable application in the treatment of wastewater.