Research Center of Heterogeneous Catalysis and Engineering Sciences, School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou 450001, China.
J Chem Phys. 2018 Nov 7;149(17):174704. doi: 10.1063/1.5048533.
Hydrogen adsorption and diffusion behaviors on noble metal model catalyst surfaces and into the subsurfaces are of paramount significance in the exploration of novel heterogenous catalytic hydrogenation reactions. We present an in-depth study of hydrogen adsorption on and diffusion into the subsurfaces of three typical 5 noble metals from three-dimensional electronically adiabatic potential energy surfaces (PESs) by interpolating plenty of density functional theory (DFT) configuration-energy points. The surfaces and subsurfaces regions of the relaxed Ir(100) and (111), Pt(100) and (111), and Au(100) and (111) surfaces, are, respectively, taken into account. For hydrogen adsorption on the (100) surfaces, the lowest adsorption energy site is the Bridge site, instead of the traditional Hollow site. Hydrogen prefers to follow the indirect pathway with a lower diffusion barrier, in the competition with the direct pathway with much higher diffusion barrier. For hydrogen diffusion on the (111) surfaces, hydrogen follows the pathway from Top site to fcc site on the surface and prefers an up-down direct pathway into the subsurface. Importantly, the nudged elastic band (NEB) based on the PESs can reproduce those results calculated from the NEB(DFT) very well. The developed highly-accurate and efficient approach based on the PESs helps us to further investigate the more complex reactant diffusion dynamics at surfaces.
在探索新型异相催化加氢反应中，贵金属模型催化剂表面和亚表面上的氢吸附和扩散行为至关重要。我们通过插值大量密度泛函理论（DFT）构形-能点，从三维电子绝热势能面（PES）深入研究了氢在三种典型 5 种贵金属上的吸附和向亚表面的扩散。考虑了弛豫 Ir(100)和(111)、Pt(100)和(111)以及 Au(100)和(111)表面的表面和亚表面区域。对于（100）表面上的氢吸附，最低吸附能位是桥位，而不是传统的空穴位。在与扩散势垒高得多的直接途径的竞争中，氢更倾向于遵循间接途径，扩散势垒较低。对于（111）表面上的氢扩散，氢沿着表面从顶位到 fcc 位的途径，并且倾向于进入亚表面的上下直接途径。重要的是，基于 PES 的推动弹性带（NEB）可以很好地再现那些基于 NEB(DFT)计算的结果。基于 PES 的开发的高度准确和高效的方法有助于我们进一步研究表面上更复杂的反应物扩散动力学。
