Multi-walled carbon nanotubes (MWCNTs) were successfully coated with two different pseudocapacitive polyoxometalates (POMs) (SiMo12O40-4 (SiMo12) and PMo12O40-3 (PMo12)) via “Layer-by-Layer” deposition. Even with merely a “single-layer” of POM, the modified nanotubes exhibited more than 2X increase in capacitance compared with that of bare nanotubes. To further improve their electrochemical performances, the deposition sequence of the POM layers was adjusted to form “alternate layer” coating to modify MWCNT. A synergistic effect on the capacitance and kinetics was observed with the alternate layer coatings. X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) also proved the successful coating of POMs on MWCNTs. The potential-pH relationship provided important insights in terms of the deposition mechanism and suggested that the bottom layer close to the electrode substrate was the dominating layer in alternate layer coated MWCNT electrodes.

Multi-walled carbon nanotubes (MWCNTs) were successfully coated with two different pseudocapacitive polyoxometalates (POMs) (SiMo12O40-4 (SiMo12) and PMo12O40-3 (PMo12)) via “Layer-by-Layer” deposition. Even with merely a “single-layer” of POM, the modified nanotubes exhibited more than 2X increase in capacitance compared with that of bare nanotubes. To further improve their electrochemical performances, the deposition sequence of the POM layers was adjusted to form “alternate layer” coating to modify MWCNT. A synergistic effect on the capacitance and kinetics was observed with the alternate layer coatings. X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM) also proved the successful coating of POMs on MWCNTs. The potential-pH relationship provided important insights in terms of the deposition mechanism and suggested that the bottom layer close to the electrode substrate was the dominating layer in alternate layer coated MWCNT electrodes.