Mixtures of Keggin type polyoxometalates were used to modify MWCNT electrodes.

PMo₁₂O₄₀^3 − (PMo) was mixed with SiW₁₂O₄₀^4 − (SiW) or PW₁₂O₄₀^3 − (PW).

The PMo–SiW electrode demonstrated redox activity very similar to that of pure PMo.

The PMo–PW mixture showed synergy and its own characteristic redox activity.

Charge storage for PMo–PW was more ideally capacitive than either pure component.