Electrochemistry of vanadium-doped ZrSiO 4: Site-selective electrocatalytic effect on nitrite oxidation

Abstract

The electrochemistry of vanadium-doped zircon (V x ZrSiO 4, 0 < x < 0.10) has been studied using abrasive-conditioned paraffin-impregnated graphite electrodes. It is compared with that of ZrSiO 4, ZrO 2, and vanadium-doped tetragonal and monoclinic zirconias. In contact with acetic/acetate and HCl + NaCl electrolytes, zirconium materials are reduced to Zr(III) at potentials near to −0.5 versus AgCl/Ag and to Zr metal at potentials more negative than −1.2 V, via proton-assisted reductive processes, influenced by the complexing action of chloride ions. Vanadium-centred oxidation processes appear at potentials from +0.2 to +0.7 V enabling for a distinction between different coordinative arrangements. ZrSiO 4 exerts a significant electrocatalytic effect on nitrite oxidation in acetic/acetate buffers, slightly enhanced in the presence of increasing vanadium loadings. Electrocatalytic data are indicative that only V centres substituting Zr are catalytically active, whereas V substituting Si are catalytically silent.