Adsorption promoted norfloxacin degradation via peroxymonosulfate activation by supercapacitor-activated carbon supported Co₂TiO₄ : The dominant role of oxygen vacancy

Although cobalt catalysts exhibit excellent performance in peroxymonosulfate (PMS) activation, agglomeration of heterogeneous metal catalysts seriously hinder their catalytic capacity. In this work, Co₂TiO₄ was loaded on supercapacitor-activated carbon (SAC) surface (xCo₂TiO₄@SAC) to enhance PMS activation for norfloxacin (NOR) degradation. Compared with Co₂TiO₄ (28.96 %), 10Co₂TiO₄@SAC achieved rapid and efficient degradation of NOR (96.55 %) within 10 min. During the degradation process, the SAC substrate enhanced the mass transfer process due to a large adsorption capacity. The catalytic mechanism was further investigated with in-situ Raman, electrochemical characterization, and X-ray photoelectron spectroscopy, indicating 10Co₂TiO₄@SAC with ample oxygen vacancies facilitated the PMS activation to generate SO₄^•−, •OH, O₂^•−, and ¹O₂. Besides, 10Co₂TiO₄@SAC was tested for practical applications in different real water environments, various organic pollutants and a fixed-bed reactor, showing that it performed satisfactorily with high resistance to interference and long-term operational stability. Finally, the possible degradation pathways of NOR was proposed based on quadrupole time-of-flight mass spectrometry and density functional theory calculation. This study revealed the excellent SAC supported metal oxide catalysts in activating PMS and demonstrated their potential application in degradation of organic pollutants. © 2024 Elsevier B.V.