Viñes Francesc, Görling Andreas
Lehrstuhl für Theoretische Chemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany.
Departament de Ciència de Materials i Química Física &, Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1, Barcelona, 08028, Spain.
Chemistry. 2020 Sep 4;26(50):11478-11491. doi: 10.1002/chem.201905672. Epub 2020 Aug 25.
Cu@Pt nanoparticles (NPs) are experimentally regarded as improved catalysts for NO storage/reduction, with higher activities and selectivities compared with pure Pt or Cu NPs, and with inverse Pt@Cu NPs. Here, a density functional theory-based study on such NP models with different sizes and shapes reveals that the observed enhanced stability of Cu@Pt compared with Pt@Cu NPs is due to energetic reasons. On both types of core@shell NPs, charge is transferred from Cu to Pt, strengthening the NP cohesion energy in Pt@Cu NPs, and spreading charge along the surface in Cu@Pt NPs. The negative surface Pt atoms in the latter diminish the NO bonding owing to an energetic rise of the Pt bands, as detected by the appliance of the d-band model, although other factors, such as atomic low coordination or the presence of an immediate subsurface Pt atom do as well. A charge density difference analysis discloses a donation/back-donation mechanism in the NO adsorption.
铜包覆铂纳米颗粒（NPs）在实验中被视为用于氮氧化物存储/还原的改进型催化剂，与纯铂或铜纳米颗粒以及反向铂包覆铜纳米颗粒相比，具有更高的活性和选择性。在此，基于密度泛函理论对不同尺寸和形状的此类纳米颗粒模型进行的研究表明，与铂包覆铜纳米颗粒相比，观察到的铜包覆铂稳定性增强是由于能量原因。在这两种类型的核壳纳米颗粒上，电荷从铜转移到铂，增强了铂包覆铜纳米颗粒中的纳米颗粒内聚能，并使电荷在铜包覆铂纳米颗粒的表面扩散。如通过d带模型的应用所检测到的，后者中表面带负电的铂原子由于铂能带的能量升高而减少了氮氧化物的键合，尽管其他因素，如原子低配位或紧邻的次表面铂原子的存在也有影响。电荷密度差分析揭示了氮氧化物吸附中的给体/反馈给体机制。
