过生长法制备准凹面体状Pt-Ni纳米合金及其甲醇氧化电催化性能(英文)

通过溶剂热法,成功制备了准凹面体状Pt-Ni合金纳米结构.不同角度的透射电镜照片和三维模型图表明,准凹面体与以立方八面体为基底,在其十二个顶点进行外延生长所形成的结构相对应.高分辨电镜(HRTEM),选区电子衍射(SAED)和X射线粉末衍射(XRD)表征结果表明,外延部分与内核部分组成成分不同.在进行系统对照实验的基础上提出了同步刻蚀-过生长机理来解释准凹面体的形成过程.电化学测试表明,准凹面体对甲醇氧化具有很高的催化活性,按质量归一的催化活性是相同条件下制备所得纯Pt颗粒的3倍,是商用Pt/C的13.6倍.X射线光电子能谱数据表明,Ni的引入有效降低了Pt的原子结合能,这可能对催化活性的提高起到了关键作用.

Synthesis of Quasi-Concave Pt-Ni Nanoalloys via Overgrowth and Their Catalytic Performance towards Methanol Oxidation

Quasi-concave Pt-Ni alloy nanostructures were synthesized via a solvothermal method, and were thought to form by epitaxial growth on the 12 vertexes of a cuboctahedron. A simultaneous etchingovergrowth process was proposed to illustrate the growth mechanism. The epitaxial layer was of different composition from the core, as confirmed by high-resolution transmission electron microscopy, selectedarea electron diffraction and powder X-ray diffraction characterizations. The concave structures exhibited high catalytic activity towards methanol oxidation. The mass-normalized catalytic activity of the concave products was ~3 times that of pure Pt nanoparticles synthesized under similar conditions, and 13.6 times that of commercial Pt/C. X-ray photoelectron spectroscopy characterization indicated that the binding energy of the concave structures shifted to lower energy, relative to the pure Pt. The modified electronic structure by introducing Ni was thought to be responsible for the enhanced catalytic activity.