Synthesis of Pt nanocrystals with different shapes using the same protocol to optimize their catalytic activity toward oxygen reduction |
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Authors: | Jing Qian Min Shen Shan Zhou Chi-Ta Lee Ming Zhao Zhiheng Lyu Zachary D Hood Madeline Vara Kyle D Gilroy Kun Wang Younan Xia |
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Affiliation: | 1. The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta 30332, GA, United States;2. School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, PR China;3. School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332, GA, United States;4. School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta 30332, GA, United States |
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Abstract: | Engineering the shape and thus surface structure of Pt nanocrystals is an effective strategy for optimizing their catalytic activities toward various reactions. However, different protocols are typically used to produce Pt nanocrystals with distinctive shapes, making it difficult to directly compare their catalytic activities owing to the complication of surface contamination. Here we demonstrate that Pt nanocrystals with a variety of shapes, including those enclosed with low- or high-index facets, can be synthesized using the same protocol by simply adjusting the concentration of reducing agent and/or the reaction time. Specifically, when the reducing agent was used at a relatively low concentration, Pt truncated cubes, cuboctahedrons, truncated octahedrons, and octahedrons were produced sequentially upon the increase in reaction time. When 67% more reducing agent was used, Pt cubes and concave cubes were obtained consecutively as the reaction time was prolonged. Our quantitative analysis suggests that the diversity of shape and difference in size can be resulted from the difference in reduction kinetics. In evaluating their structure–activity relationship for oxygen reduction, it was established that the high-index facets on Pt concave cubes possessed a specific activity of 6.3 and 1.3 times greater than those of Pt cubes and octahedrons exposed by {1?0?0} and {1?1?1} facets, respectively. This work not only offers a general method for the synthesis of Pt nanocrystals having diverse shapes and thus different types of facets but also highlights the significance of reduction kinetics in controlling the structure evolution of other metal nanocrystals. |
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Keywords: | Corresponding author at: The Wallace H Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University Atlanta 30332 GA United States |
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