分别在酸性和碱性溶液中,结合旋转圆盘电极技术和电化学石英晶体微天平技术原位考察了钯铁合金催化剂对氧还原反应催化活性的稳定性.发现在酸性溶液中,钯铁合金催化剂对氧还原反应的催化活性不稳定,原因是钯铁合金催化剂在酸性溶液中发生电化学,化学溶解;在碱性溶液中,覆盖在电极表面的钯铁合金催化剂的质量及电化学活性面积在电化学扫描过程中不发生明显变化,保持对氧还原反应的催化活性,证明钯铁合金催化剂在碱性介质中非常稳定.
The stability of Pd-Fe alloy catalysts for the oxygen reduction reaction (ORR) was characterized in situ by using the rotating disk electrode and electrochemical quartz crystal microbalance (EQCM) techniques, both in acidic and alkaline solutions. The alloy catalyst was found to be unstable in the acidic solution because of the electrochemical and chemical dissolution of the catalyst. This dissolution resulted in a reduction of activity for the oxygen reduction reaction and also a reduction in the mass of the catalyst. In an alkaline solution, the mass of the Pd-Fe alloy catalyst deposited on the electrode surface and its electrochemically active surface area hardly changed. Consequently, the catalyst kept its activity for stable oxygen reduction.