Highly Effective PdCu Electrocatalysts Supported on Polyelectrolyte Functionalized Titanium Dioxide for Direct Formic Acid Fuel Cells

A highly efficient and CO tolerant PdCu electrocatalysts supported on amino-rich, cationic poly(diallyl dimethyl ammonium chloride)(PDDA) functionalized TiO 2 (PdCu/TiO 2 (P)-C) has been developed. The catalysts were characterized by transmission electron microscopy (TEM),X-ray diffraction (XRD)，cyclic voltammograms and chronoamperometry. The PtCu particles with average size ∼3.5 nm are well dispersed on TiO 2 (P). PdCu/TiO 2 (P)-C catalysts exhibit a superior electrocatalytic activity and stability for the formic acid oxidation reaction compared with the Pd/TiO 2 (P)-C. Electrochemical measurements indicate that PdCu/TiO 2 (P)-C(1:2) catalyst has the best performance for formic acid electro-catalytic oxidation in terms of durability and Pd-mass activity among three catalysts (Pd 1 Cu 1 ,Pd 1 Cu 2 ,Pd 1 Cu 3 ). The possible reason is that the addition of Cu is beneficial to lower appropriately the d-band center of Pd and increase the electrochemical active surface area of the PdCu/TiO 2 (P)-C nanocatalysts, but when the content of Cu rises to a certain extent, the morphology of the catalyst nanoparticles will transform into linear structure leading to increased particle size.