Solvothermal Synthesis of Platinum Alloy Nanoparticles for Oxygen Reduction Electrocatalysis

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• 作者：Michael K. Carpenter ; Thomas E. Moylan ; Ratandeep Singh Kukreja ; Mohammed H. Atwan ; Misle M. Tessema
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：May 23, 2012
• 年：2012
• 卷：134
• 期：20
• 页码：8535-8542
• 全文大小：424K
• 年卷期：v.134,no.20(May 23, 2012)
• ISSN：1520-5126

文摘

Platinum alloy nanoparticles show great promise as electrocatalysts for the oxygen reduction reaction (ORR) in fuel cell cathodes. We report here on the use of N,N-dimethylformamide (DMF) as both solvent and reductant in the solvothermal synthesis of Pt alloy nanoparticles (NPs), with a particular focus on Pt鈥揘i alloys. Well-faceted alloy nanocrystals were generated with this method, including predominantly cubic and cuboctahedral nanocrystals of Pt₃Ni, and octahedral and truncated octahedral nanocrystals of PtNi. X-ray diffraction (XRD) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), coupled with energy dispersive spectroscopy (EDS), were used to characterize crystallite morphology and composition. ORR activities of the alloy nanoparticles were measured with a rotating disk electrode (RDE) technique. While some Pt₃Ni alloy nanoparticle catalysts showed specific activities greater than 1000 渭A/cm²_Pt, alloy catalysts prepared with a nominal composition of PtNi displayed activities close to 3000 渭A/cm²_Pt, or almost 15 times that of a state-of-the-art Pt/carbon catalyst. XRD and EDS confirmed the presence of two NP compositions in this catalyst. HAADF-STEM examination of the PtNi nanoparticle catalyst after RDE testing revealed the development of hollows in a number of the nanoparticles due to nickel dissolution. Continued voltage cycling caused further nickel dissolution and void formation, but significant activity remained even after 20鈥?00 cycles.