Carbon Monoxide-Assisted Size Confinement of Bimetallic Alloy Nanoparticles

详细信息    查看全文

• 作者：Chunhua Cui ; Lin Gan ; Maximilian Neumann ; Marc Heggen ; Beatriz Roldan Cuenya ; Peter Strasser
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：April 2, 2014
• 年：2014
• 卷：136
• 期：13
• 页码：4813-4816
• 全文大小：270K
• 年卷期：v.136,no.13(April 2, 2014)
• ISSN：1520-5126

文摘

Colloid-based chemical synthesis methods of bimetallic alloy nanoparticles (NPs) provide good monodispersity, yet generally show a strong variation of the resulting mean particle size with alloy composition. This severely compromises accurate correlation between composition of alloy particles and their size-dependent properties. To address this issue, a general CO adsorption-assisted capping ligand-free solvothermal synthesis method is reported which provides homogeneous bimetallic NPs with almost perfectly constant particle size over an unusually wide compositional range. Using Pt鈥揘i alloy NPs as an example, we show that variation of the reaction temperature between 160 and 240 掳C allows for precise control of the resulting alloy particle bulk composition between 15 and 70 atomic % Ni, coupled with a constant mean particle size of 4 nm. The size-confining and Ni content-controlling role of CO during the nucleation and growth processes are investigated and discussed. Data suggest that size-dependent CO surface chemisorption and reversible Ni-carbonyl formation are key factors for the achievement of a constant particle size and temperature-controlled Ni content. To demonstrate the usefulness of the independent control of size and composition, size-deconvoluted relations between composition and electrocatalytic properties are established. Refining earlier reports, we uncover intrinsic monotonic relations between catalytic activity and initial Ni content, as expected from theoretical considerations.