Synthesis of structurally ordered platinum-iron catalysts with enhanced oxygen reduction reaction activity
- 2016年第22卷 
为提高燃料电池用贵金属铂催化氧还原反应性能，采用改进的多元醇法制备不同金属比例的碳载铂铁合金催化剂（D-Pt3Fe/C和D-PtFe/C）前驱体. 随后通过优化在惰性气体环境中的高温煅烧条件，将结构无序的合金结构转变为结构有序的合金催化剂（O-Pt3Fe/C和O-PtFe/C）. 利用X射线粉末衍射（XRD）、透射电子显微镜（TEM）、电感耦合等离子体原子发射光谱（ICP-AES）和X射线光电子能谱（XPS）对所制得催化剂进行结构表征. 结果发现，所制得催化剂的合金纳米颗粒尺寸分布均一（4 ~ 6 nm），且均匀负载于碳载体上. 利用循环伏安法（CV）、线性扫描伏安法（LSV）对所制得催化剂进行电化学性能评估. 结果表明，O-PtFe/C的催化活性高于O-Pt3Fe/C，其质量活性（271.54 mA•g-1Pt）和比活性（0.73 mA•cm-2Pt）分别是商业JM Pt/C催化剂的4.3倍和7.3倍. 两种结构有序铂铁催化剂催化氧还原反应活性均高于商业JM Pt/C催化剂.To improve oxygen reduction reaction catalytic activity of the precious metals platinum for fuel cell, the precursors of carbon-supported structurally disordered platinum-iron alloy (D-Pt3Fe/C and D-PtFe/C) catalysts with different compositions were synthesized via a modified polyol reduction method. Then, by optimizing the annealing conditions in the inert gas, we turned the structurally disordered platinum-iron alloy to the structurally ordered platinum-iron alloy (O-Pt3Fe/C and O-PtFe/C) catalysts. The structural characterizations of the as-prepared catalysts were performed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS). The results showed that the as-prepared structurally ordered platinum-iron alloy nanoparticles with a small size in edge length of 4 ~ 6 nm were highly dispersed on the carbon support. The electrocatalytic performances of the as-prepared catalysts were evaluated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). It was found that the catalytic activity of O-PtFe/C was enhanced as compared to that of O-Pt3Fe/C. The mass activity and specific activity of O-PtFe/C are 271.54 mA•g-1Ptand 0.73 mA•cm-2Pt, respectively, which are 4.3 and 7.3 times higher than those of commercial JM Pt/C catalyst. The catalytic activities of both the as-prepared structurally ordered platinum-iron alloy catalysts for oxygen reduction reaction were higher than that of JM Pt/C catalyst.