Investigations of multilayer polyoxometalates-modified carbon nanotubes for electrochemical capacitors

► Multiwall carbon nanotube was modified by superimposing two types polyoxometalates. ► The superimposed POM layers showed a synergistic effect from both POM layers. ► The specific capacitance was quadrupled after two layers alternate coatings of POM. ► The bottom POM layer dominates the chemistry and kinetics of the overall coating.