Wang Siwen, Omidvar Noushin, Marx Emily, Xin Hongliang
Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Phys Chem Chem Phys. 2018 Feb 28;20(9):6055-6059. doi: 10.1039/c8cp00102b.
Geometry-based reactivity descriptors, e.g., regular, generalized, and orbitalwise coordination numbers, were used for unraveling intrinsic size effects of Au nanocatalysts towards CO oxidation. For an ensemble of Au nanoparticles with varying sizes and shapes, s-orbital coordination numbers (CN) linearly correlate with *CO and *O adsorption energies at the on-top and hollow sites, respectively, outperforming their regular (CN) and generalized (C[combining macron]N[combining macron]) counterparts attributed to an explicit consideration of interatomic interactions. To take into account the geometric strain of surface atoms, the embedded-atom method (EAM) potential trained with ab initio energies of the bulk, nanoclusters, and extended surfaces at the GGA-PBE level was used for optimizing the Wulff-shaped, free-standing Au nanoparticles up to 7.2 nm. Microkinetic analysis of CO oxidation on extended {111}, {100}, {211}, and {532} surfaces, along with a facile and accurate prediction of *CO and *O adsorption energies at nanoparticles using the herein developed structure-reactivity relationships, captures experimentally measured activity trends of supported Au nanoparticles of varying sizes on a wide variety of metal oxides and illustrates the importance of under-coordinated atoms and insensitivity of surface strains in Au-catalyzed CO oxidation.
基于几何结构的反应性描述符，例如规则、广义和轨道配位数值，被用于揭示金纳米催化剂对一氧化碳氧化反应的内在尺寸效应。对于一组具有不同尺寸和形状的金纳米颗粒，s轨道配位数值（CN）分别与顶位和空心位上的CO和O吸附能呈线性相关，由于明确考虑了原子间相互作用，其性能优于规则（CN）和广义（C̅N̅）对应物。为了考虑表面原子的几何应变，使用在GGA-PBE水平下用体相、纳米团簇和扩展表面的从头算能量训练的嵌入原子法（EAM）势，对高达7.2 nm的Wulff形状的独立金纳米颗粒进行优化。对扩展的{111}、{100}、{211}和{532}表面上的一氧化碳氧化反应进行微观动力学分析，以及使用本文建立的结构-反应性关系对纳米颗粒上的CO和O吸附能进行简便而准确的预测，捕捉了在各种金属氧化物上不同尺寸的负载型金纳米颗粒的实验测量活性趋势，并说明了欠配位原子的重要性以及表面应变在金催化一氧化碳氧化反应中的不敏感性。
