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Enhanced Catalysis of Pt3 Clusters Supported on Graphene for N–H Bond Dissociation
CCS Chemistry ( IF 11.2 ) Pub Date : 2019-06-04 , DOI: 10.31635/ccschem.019.20180031
Chaonan Cui , Zhixun Luo , Jiannian Yao

We report an in-depth study of catalytic N–H bond dissociation with typical platinum clusters on graphene supports. Among all the pristine grapheneand defective graphene-supported Pt clusters of different sizes that were studied, the Pt3/G cluster possesses the highest reactivity and lowest activation barriers for each step of N–H dissociation in the decomposition of ammonia. In analyzing the reaction coordinates and projected density of states of the outermost orbitals, we found that the standing triangular Pt3 on graphene creates prominent Lewis acid/base pair sites, which accommodate the adsorption and subsequent dissociation of *NHx. In comparison, Pt1 lacks complementary active sites (CAS), causing it to be adverse to nucleophilic reactions, and in contrast, the Pt13 cluster has weakened interactions and depleted charge density from the support, resulting in the elimination of the CAS effect. A stable pyramid-structured Pt4 also develops Lewis acid/base sites, especially on defective graphene, but the density of states is still lower than the stand-up Pt3/G. These findings strongly demonstrate the importance and necessity of cluster active sites for catalytic reactions of polar molecules, novel three-atoms metal cluster catalysis, and the selectivity and catalytic performance in the designing of ammonia fuel cells.

中文翻译:

石墨烯支持的Pt3团簇增强N-H键解离的催化作用

我们报告了对石墨烯载体上典型的铂簇的催化NH键解离的深入研究。在所研究的所有原始石墨烯和缺陷石墨烯负载的Pt簇中,对于氨分解过程中N–H离解的每个步骤,Pt3 / G簇均具有最高的反应性和最低的活化势垒。在分析最外层轨道的反应坐标和状态的预计密度时,我们发现石墨烯上的直立三角形Pt3创建了突出的路易斯酸/碱对位点,这些位点适应了* NHx的吸附和随后的解离。相比之下,Pt1缺乏互补的活性位点(CAS),导致它对亲核反应不利,相反,Pt13团簇的相互作用减弱,支持物的电荷密度降低,从而消除了CAS效应。稳定的金字塔结构的Pt4也会形成路易斯酸/碱位点,尤其是在有缺陷的石墨烯上,但态密度仍低于立式Pt3 / G。这些发现强烈证明了簇活性位对于极性分子催化反应,新型三原子金属簇催化的重要性和必要性,以及氨燃料电池设计中的选择性和催化性能。
更新日期:2020-06-24
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