Structure Sensitivity of NO Adsorption鈥揇issociation on Pdn (n = 8, 13, 19, 25) Clusters

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• 作者：Xuejing Liu ; Dongxu Tian ; Suzhen Ren ; Changgong Meng
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：June 11, 2015
• 年：2015
• 卷：119
• 期：23
• 页码：12941-12948
• 全文大小：408K
• ISSN：1932-7455

文摘

NO adsorption and dissociation on subnanometer Pd_n (n = 8, 13, 19, 25) clusters were first studied with GGA-DFT. The transition structures of the NO dissociating on the potential-energy surfaces were derived using the climbing image nudged-elastic-band (CI-NEB) method. The preferred NO adsorption positions are bridge sites on Pd_n (n = 8, 19) and hollow sites on Pd_n (n = 13, 25). The NO adsorption energy values on hollow sites of icosahedron-based Pd_n (n = 13, 25) are relatively higher than that on the bridge site of octahedral Pd₁₉. However, the NO dissociation barrier on octahedral Pd₁₉ is lower than that on icosahedron-based Pd_n (n = 13, 25) clusters. These results suggest on a Pd_n (n = 8, 13, 19, 25) scale the NO activity may no longer rely on the cluster size but rather on the geometric structure of Pd_n clusters. The coordination number of the NO adsorption site is found to be the key factor to determine the structure sensitivity of NO adsorption and dissociation. The charge difference and Hirshfeld charges reveal that the charge transfer is from the Pd_n clusters to NO and increases upon NO dissociation. PDOS reveals that the 3蟽, 4蟽, 5蟽, 1蟺, and 2蟺 peaks of NO are sensitive not to Pd_n cluster size but to NO adsorption sites. Our calculations may provide an insight into structure-sensitive Pd-based catalysts for NO removal on a subnanometer scale.