Uniform size and composition tuning of PtNi octahedra for systematic studies of oxygen reduction reactions

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• 作者：Shang-Wei Chou ; Ying-Ren Lai ; Ya Yun Yang ; Chih-Yuan Tang ; Michitoshi Hayashi ; Hsieh-Chih Chen ; Hui-Lung Chen ; Pi-Tai Chou
• 关键词：PtNi octahedra ; Shape control ; Oxygen reduction reaction ; Volcano-shaped plot ; DFT calculations ; Surface energy ; Adsorption energy
• 刊名：Journal of Catalysis
• 出版年：January, 2014
• 年：2014
• 卷：309
• 期：Complete
• 页码：343-350
• 全文大小：2222 K

文摘

Uniform size and composition tuning of PtNi octahedra enclosed by 8 {1 1 1} facets were achieved by the control of specific crystal facet-surfactant bindings. In this chemical method, the optimal ratio of dioctyl amine to oleic acid is a key factor in the formation of PtNi octahedra with different alloying compositions, Pt:Ni = 18:6, 12:12, and 10:14. Careful electrochemical examinations show that the oxygen reduction reaction (ORR) mass activity and specific area activity of all PtNi octahedra outperform those of commercial Pt/C catalyst. The volcano-shaped trend of ORR enhancement proves that Pt₁₂Ni₁₂ octahedra have superior ORR activities. Further firm support is provided by the theoretical approach, which concludes that the adsorption energies of the H, O, O₂, and OH species on a surface of Pt₁₂Ni₁₂(1 1 1) are much higher than those for Pt₁₈Ni₆(1 1 1) and Pt₁₀Ni₁₄(1 1 1) counterparts, whereas the molecularly adsorbed H₂O product is calculated to be the lowest in adsorption energy on the Pt₁₂Ni₁₂(1 1 1) surface.