Electrocatalytic oxidation of ascorbic acid on a lithium-doped tantalum oxide film coated electrode

In this work, lithium-doped tantalum oxide (lithium-Ta2O5) particles were synthesized using a low-temperature hydrothermal method. X-ray photoelectron spectroscopy (XPS) indicated that the state of lithium on the Ta2O5 surface is the Li+ form. The crystal phase of the samples was analyzed using X-ray diffraction (XRD). The analysis revealed that the lithium-Ta2O5 particles are well crystallized into an orthorhombic phase. Calculation from density functional theory (DFT) indicated that the band gap of Ta2O5 narrows when it is doped with lithium, resulting in improved conductivity and electrocatalytic activity over Ta2O5. The electrocatalytic activity of a lithium-Ta2O5 film coated electrode was investigated in a 0.1 mol dm−3 KCl solution containing ascorbic acid (AA) using cyclic voltammetry (CV). The lithium-Ta2O5 film coated electrode has excellent electrocatalytic activity toward the oxidation of AA with much reduced overpotential. The anodic peak potential of AA shifted from 0.72 V (versus Ag|AgCl) on a bare glassy carbon electrode (GCE) to 0.42 V on the lithium-Ta2O5 film coated electrode.