Pd-modified TiO_2 electrode for electrochemical oxidation of hydrazine, formaldehyde and glucose

摘要

The electrocatalysis of the oxidation of hydrazine, formaldehyde and glucose on a nanoporous Pd-modified TiO_2 electrode, prepared by the hydrothermal process, was investigated in 0.1 M NaOH solutions. The electrocatalytic activity of the Pd-modified TiO_2 electrode for the electrochemical oxidation of hydrazine, formaldehyde and glucose is characterized by the low onset potentials of -0.80, -0.70 and -0.85 V (vs Ag, AgCl), respectively. Compared to the oxidation of formaldehyde and glucose, the hydrazine oxidation on the Pd-modified TiO_2 presents the highest anodic oxidation current densities, showing that the Pd-modified TiO_2 electrode is more electro-active for the hydrazine oxidation than for the oxidation of formaldehyde and glucose. Chronoamperograms at different concentrations of hydrazine and formaldehyde showed that the Pd-modified TiO_2 electrode is a promising electrochemical sensor for the detection of hydrazine with a sensitivity of 0.554 mA cm~2 mM_1 and a detection limit of 0.023 mM, and for the detection of formaldehyde with a sensitivity of 0.20667 mA cm~2 mM~1 and a detection limit of 0.015 mM. However, it was found from the chronoamperometric responses at various glucose concentrations that a linear plot of the anodic oxidation current density versus glucose concentration developed only in the range of 7-35 mM glucose while an obvious deviation from the linear relationship was observed at both low and large glucose concentrations. Results show that the prepared Pd-modified TiO_2 electrode could be applied to the direct liquid (hydrazine, formaldehyde, and glucose) fuel cells as an effective anodic catalyst, in addition to be a promising electrochemical sensor for the detection of hydrazine and formaldehyde.