ZrC-C and ZrO2-C as Novel Supports of Pd Catalysts for Formic Acid Electrooxidation

The Pd/ZrCC and Pd/ZrO2C catalysts with zirconium compounds ZrC or ZrO2 and carbon hybrids as novel supports for direct formic acid fuel cell (DFAFC) have been synthesized by microwave-assisted polyol process. The Pd/ZrCC and Pd/ZrO2C catalysts have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM), and electrochemical measurements. The physical characteristics present that the zirconium compounds ZrC and ZrO2 may promote the dispersion of Pd nanoparticles. The results of electrochemical tests show that the activity and stability of Pd/ZrCC and Pd/ZrO2C catalysts show higher than that of Pd/C catalyst for formic acid electrooxidation due to anti-corrosion property of zirconium compounds ZrC, ZrO2, and metalsupport interaction between Pd nanoparticles and ZrC, ZrO2. The Pd/ZrCC catalyst displays the best performance among the three catalysts. The peak current density of formic acid electrooxidation on Pd/ZrCC electrode is nearly 1.63 times of that on Pd/C. The optimal mass ratio of ZrC to XC-72 carbon is 1:1 in Pd/ZrCC catalyst with narrower particle size distribution and better dispersion on surface of the mixture support, which exhibits the best activity and stability for formic acid electrooxidation among all the samples.