Anchoring Effect of Exfoliated-Montmorillonite-Supported Pd Catalyst for the Oxygen Reduction Reaction

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• 作者：Meirong Xia ; Wei Ding ; Kun Xiong ; Li Li ; Xueqiang Qi ; Siguo Chen ; Baoshan Hu ; Zidong Wei
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：May 23, 2013
• 年：2013
• 卷：117
• 期：20
• 页码：10581-10588
• 全文大小：590K
• 年卷期：v.117,no.20(May 23, 2013)
• ISSN：1932-7455

文摘

We report a combined experimental and computational study on exfoliated montmorillonite (ex-MMT) nanoplatelet supported palladium catalysts. The experimental results revealed that the Pd/ex-MMT catalysts were more stable than Pd/C catalysts in an acidic environment. The results from the density functional theory (DFT) calculations revealed that the O atoms from the AlO₆ octahedra in ex-MMT act as anchoring sites for Pd nanoparticles (NPs) that are strongly bound to the ex-MMT support. The partial density of state calculations indicated that the Pd-d states and the O(AlO₆)-p states have similar energy. Therefore, it is very easy for electrons to transfer between these states and to form Pd鈥揙(AlO₆) bonds. In addition, the defective or destroyed SiO₄ tetrahedra can be restructured directly by the O atoms from O₂ molecules or indirectly by the intermediates from the reduction of O₂. The DFT calculations also revealed that the defects in the ex-MMT supports provide anchor sites for the Pd catalysts to tightly bind on the ex-MMT supports. For Pd₅/ex-MMT, with the attacks of O_ads, the Pd atoms in the Pd₅ cluster remain linked together through a Pd鈥揚d bond and are anchored tightly on the ex-MMT. However, for Pd/C, the Pd atoms in the Pd₅ cluster are not only oxidized but also separated from the carbon bulk.