Nd-Fe-WO cyanide-bridged mixed complexes modified platinum electrode was successfully prepared by using electrodeposition method for the first time. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to characterize the morphology and crystalline lattice structure of the modified materials. Formic acid electrocatalytic oxidation behavior on this modified electrode was evaluated by means of cyclic voltammetry and chronoamperometry. The results indicated that the electrocatalytic oxidation current density of formic acid on modified electrode was about 10 times more than on bare Pt electrode, and CV anodic limit potential had significant effect on peak figuration of absorption intermediate in the reverse scan. Moreover, the influence of H^＋ and SO concentration in electrolyte solution on the voltammetric characteristics of formic acid electrocatalytic oxidation was also studied, it showed that the main oxidation peak s potential increased with increasing H^＋ concentration, however, decreased with increasing SO concentration, but being coexistence of H^＋ and SO , the effect of H^＋ played a dominant role. This phenomenon revealed that the rate-determining step of electrocatalytic oxidation of formic acid on modified electrode was correlative with de-protonation process, and the adsorption of SO /HSO would promote the forward oxidation reaction. These conclusions provided new experimental evidences for explaining the mechanism of formic acid electrocatalytic oxidation. Meanwhile, the electrode stability experiments as well as chronoamperometry also demonstrated that the newly developed modified electrode possessed much better electrocatalytic activity and tolerance to toxic intermediate contamination.

Key words: formic acid, electrocatalytic oxidation, cyanide-bridged mixed complexes, modified electrode