Fe对Pt-Fe/C催化剂电催化氧还原反应活性的影响

制备了用作直接甲醇燃料电池的碳载Pt-Fe(Pt-Fe/C)阴极催化剂, X射线能量色散谱(EDX)、X射线衍射谱和电化学测量的结果表明, 在Pt-Fe/C催化剂中, Fe以3种形式存在. 质量分数大约为20％的Fe进入Pt的晶格, 形成Pt-Fe合金, 质量分数大约为80％的Fe没有进入Pt的晶格而以Fe和Fe2O3的形式单独存在. 该催化剂经酸处理后, 非合金化Fe和Fe2O3被溶解, 而使Pt-Fe/C催化剂的电化学活性比表面积要比未经酸处理前的增加约30％左右, 导致Pt-Fe/C催化剂对氧还原的电催化活性优于未经酸处理前的Pt-Fe/C催化剂. 研究结果表明, Pt-Fe/C催化剂的电化学活性比表面积对氧还原的电催化活性起重要的作用, 另外, 只有与Pt形成合金的Fe能提高Pt对氧还原的电催化活性, 而非合金化的Fe对Pt催化剂对氧还原的电催化活性基本没有影响.

Effect of Fe on Electrocatalytic Activity of Pt-Fe/C Catalyst for Oxygen Reduction

In this paper, the carbon supported Pt-Fe(Pt-Fe/C) cathodic catalyst in the direct methanol fuel cell was prepared. The results of the energy dispersive X-ray(EDX) analysis, X-ray reflection spectroscopy(XRD) and electrochemical measurements indicate that in the Pt-Fe/C catalyst, Fe exists as the three forms. About 20%(mass fraction) Fe enters the crystal lattice of Pt, forming the alloy with Pt. About 80%(mass fraction) Fe does not enter the crystal lattice of Pt and exists as Fe and Fe2O3. After the Pt-Fe/C catalyst being treated with acid , non-alloying Fe and Fe2O3 in the catalyst are dissolved. Therefore, the electrochemically active specific surface area of the Pt-Fe particles in the Pt-Fe/C catalyst after the acid treatment is 30% larger than that of the Pt-Fe/C catalyst before the acid treatment. Thus, the electrocatalytic activity of the Pt-Fe/C catalyst after the acid treatment for the oxygen reduction is higher than that of the Pt-Fe/C catalyst before the acid treatment. It illustrates that the electrochemically active specific surface area of the Pt-Fe particles in the Pt-Fe/C catalyst can significantly affects the electrocatalytic activity of the Pt-Fe/C catalyst for the oxygen reduction. In addition, it also demonstrates that only alloying Fe can increase the electrocatalytic activity of the Pt for the oxygen reduction and non-alloying Fe has no such effect.