Preparation of TiO₂-nanorods supported Pd catalyst and its electrocatalytic oxidation on formic acid

TiO₂ nanorods (TiO₂-R) and irregular TiO₂ (TiO₂-I) with anatase phase structure are synthesized by hydrothermal synthesis and inorganic sol gel method, respectively. Using as-prepared TiO₂ as support, Pd/TiO₂ catalysts are prepared by using sodium ethylenediamine tetracetate (EDTA) as complexing agent and NaBH4 as reductant. The studies of transmission electron microscopy (TEM) and X-ray diffraction (XRD) reveal that the average particle size of Pd/TiO₂-R catalyst is very similar to that of Pd/TiO₂-I catalyst. Cyclic voltammetry measurements show that the peak current of formic acid oxidation at Pd/TiO₂-R catalyst increases by 70%. Chronoamperometric measurements indicate that the current density at the Pd/TiO₂-R catalyst electrode at 3000 s is almost 16 times larger than that at the Pd/TiO₂-I catalyst electrode. These electrochemical experiments show that the electrocatalytic activity and long-term operation stability of Pd/TiO₂-R catalyst are much better than that of Pd/TiO₂-I catalyst for formic acid oxidation in acidic media, indicating that TiO₂ nanorods support material can effectively promote the electrocatalytic activity and stability of Pd catalyst for formic acid electrooxidation. Likely, TiO₂ nanorods possess good electronic conductivity and abundant surface oxygen-containing groups, which improve the electrocatalytic activity and the anti-poisoned performance of Pd catalyst for the formic acid electrooxidation. Thus, TiO₂ nanorods with anatase phase structure possess the potential application prospect in direct formic acid fuel cell (DFAFC).