Improved degradation of iohexol using electro-enhanced activation of persulfate by a CuxO-loaded carbon felt with carbon nanotubes as an interlayer

•A CuxO-loaded carbon felt with carbon nanotubes as an interlayer was fabricated.•PMS could be effectively activated by the electrically enhanced CuxO/CNT/CF.•The catalytic performance and stability of the electrodes can be improved by CNT.•The degradation efficiency of iohexol (IOH) could reach 100 % within 25 min.•Both nonradical and radical-mediated PS activation are involved in the degradation.