UTC Power, South Windsor, CT 06074, USA.
Phys Chem Chem Phys. 2013 Sep 28;15(36):15078-90. doi: 10.1039/c3cp52252k.
A comprehensive experimental study was conducted on the dealloying of PdNi6 nanoparticles under various conditions. A two-stage dealloying protocol was developed to leach >95% of Ni while minimizing the dissolution of Pd. The final structure of the dealloyed particle was strongly dependent on the acid used and temperature. When H2SO4 and HNO3 solutions were used in the first stage of dealloying, solid and porous particles were generated, respectively. The porous particles have a 3-fold higher electrochemical surface area per Pd mass than the solid ones. The dealloyed PdNi6 nanoparticles were then used as a core material for the synthesis of core-shell catalysts. These catalysts were synthesized in gram-size batches and involved Pt displacement of an underpotentially deposited (UPD) Cu monolayer. The resulting materials were characterized by scanning transmission electron microscopy (STEM) and in situ X-ray diffraction (XRD). The oxygen reduction reaction (ORR) activity of the core-shell catalysts is 7-fold higher than the state-of-the-art Pt/C. The high activity was confirmed by a more than 40 mV improvement in fuel cell performance with a Pt loading of 0.1 mg cm(-2) by using the core-shell catalysts.
进行了一项关于 PdNi6 纳米粒子在不同条件下脱合金的综合实验研究。开发了一种两阶段脱合金方案，可浸出超过 95%的 Ni，同时最大限度地减少 Pd 的溶解。脱合金粒子的最终结构强烈依赖于所使用的酸和温度。在脱合金的第一阶段使用 H2SO4 和 HNO3 溶液时，分别生成了固体和多孔粒子。多孔粒子的 Pd 质量电化学表面积比固体粒子高 3 倍。然后将脱合金的 PdNi6 纳米粒子用作核壳催化剂合成的核心材料。这些催化剂以克级批次合成，涉及欠电位沉积 (UPD) Cu 单层的 Pt 置换。通过扫描透射电子显微镜 (STEM) 和原位 X 射线衍射 (XRD) 对所得材料进行了表征。核壳催化剂的氧还原反应 (ORR) 活性比最先进的 Pt/C 高 7 倍。使用核壳催化剂，通过将 Pt 负载量提高到 0.1 mg cm(-2)，可使燃料电池性能提高 40 mV 以上，从而证实了其高活性。
