Co3O4 nanosheets modified by Ni@C nanoparticles as effective flow-through electrode for electro-activation of PMS: Ni@C as electron shuttle for accelerated Co3+/Co2+ cycle in bulk Co3O4

Electro-assisted activation of peroxymonosulfate (EA-PMS) by transition metals oxides (TMOs) has been extensively studied for the removal of organic pollutants. Despite TMOs possess considerable activity and affinity to PMS, their poor bulk conductivity still limits the electron exchange during the TM δ/δ+1 redox cycle, especially the efficient reduction of TM δ+1 via cathodic process. In this study, carbon felt loaded with modified Co 3 O 4 nanosheets (Co@FCF) was fabricated and applied as the flow-through electrode of EA-PMS process, where the Co 3 O 4 nanosheets were embedded with numerous metallic Ni particles encapsulated within carbon layers (Ni@C). Driven by weak electric current, continuous electrons can be supplied to the bulk Co 3 O 4 from the electron-rich Ni@C nanoparticles, resulting in accelerated Co 3+ /Co 2+ cycle, enhanced production of SO 4 ·− and improved energy utilization efficiency. Electrochemical tests along with density functional theory calculations indicate that the unique structure of Co@FCF played essential role in the enhanced performance.