A Class of (Pd-Ni-P) Electrocatalysts for the Ethanol Oxidation Reaction in Alkaline Media

A class of Pd-Ni-P electrocatalysts are prepared for the ethanol electrooxidation reaction (EOR). X-ray diffraction and transmission electron microscope reveal that the synthesized Pd-Ni-P catalyst possesses a more amorphous structure with smaller particle sizes when compared with a Pd-Ni sample without P and a control Pd black (Pd-blk) sample. The Pd-Ni-P catalyst contains double the number of electrocatalytically active sites (12.03%) compared with the Pd-Ni (6.04%) and Pd-blk (5.12%) samples. For the EOR, the Pd-Ni-P catalyst has the lowest onset potential (-0.88 V vs SCE), the most negative peak potential (-0.27 V vs SCE), and the highest EOR activity in 0.1 M KOH solution. Moreover, a 110 mV decrease in overpotential is observed for the EOR on the Pd-Ni-P catalyst compared with the Pd-blk catalyst. A Tafel slope of 60 mV/dec at low polarization potentials (<-0.76 V vs SCE) was obtained for EOR at a Pd-Ni-P-coated electrode with a reaction rate constant of 2.8 x 10(-4) cm.S-1.M-1 at -0.3 V vs SCE in KOH media. Finally, we find that the electrooxidation of ethanol on the Pd-Ni-P catalyst undergoes a 4-electron process to acetate.