Fabrication and electrochemical behavior of vanadium-substituted keggin-type polyoxometalates multilayer films on 4-aminobenzoic acid modified glassy carbon electrodes

Two Vanadium-substituted Keggin-type polyoxometalates, K3H2[alpha-SiVW11O40]center dot 6H(2)O (SiVW11) and K4H2[gamma(1, 2)-SiV2W10O40]center dot 4H(2)O (SiV2W10) were first successfully immobilized on 4-aminobenzoic acid modified glass carbon electrodes respectively by layer-by-layer assembly with poly (ethylenimine) (PEI) as counterions. The regular growth processes were monitored by cyclic voltammetry (CV), and it was proved that the multilayer films were uniform and stable. The cyclic voltammetry results indicated that the electrochemical behavior of two multilayer films was similar, and their redox couples are pH- and scan rate-dependent. The multilayer films show favorable electrocatalytic active toward the reduction of NO2-, IO3- and H2O2.