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

Abstract

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 × 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.