An Unsupported Metal/Non-metal Compound Pd-Ni-P for Catalytic Ethanol Oxidation Reaction in Alkaline Electrolyte

摘要

An unsupported Pd-Ni-P compound containing metals Pd-Ni and non-metal phosphorus (P) elements is synthesized for catalytic ethanol oxidation reaction (EOR) in alkaline media. As characterized with X-ray diffraction (XRD), BET-surface area, and transmission electron microscopy (TEM), the Pd-Ni-P has more amorphous structure, higher BET surface area, and smaller particle size than the Pd-Ni and Pd nano-materials without doping phosphorus. The catalytic activity of EOR at the catalyst coated electrode in 0.1M KOH was investigated. The catalytic wave of the Pd-Ni-P coated electrode in 0.1M KOH containing 1 M ethanol extends a wide potential range from -0.9V to +0.4V (vs. SCE) with a peak potential (Ep) at -0.27V, which is 50 mV more negative than that of EOR at Pd-Ni catalyst coated electrode (Ep = -0.23V), and 110 mV more negative than that of EOR at Pd black coated electrode (Ep =-0.16V). The Pd-Ni-P coated electrode also shows the highest catalytic peak current for EOR. The KOH concentration substantially affects the catalytic activity of Pd-Ni-P. When KOH concentration changes from 0.1 M to 2.0 M, the catalytic current at the Pd-Ni-P coated electrode is increased from 19 mA/cm~2 to 350 mA/cm~2 with 1 M ethanol. The catalytic process of EOR at Pd-Ni-P catalyst belongs to 4-electron oxidation to produce acetate in the alkaline media.