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arXiv 2204.02812cond-mat.mtrl-sci
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Pd $\rm_{1-x}$ Ag $\rm_{x}$表面合金吸附和脱附性质的第一性原理和Monte Carlo研究

First principles and Monte Carlo studies of adsorption and desorption properties from Pd$\rm_{1-x}$Ag$\rm_{x}$ surface alloy

S. S. Awulachew, K. N. Nigussa

摘要:

Pd $\rm_{1-x}$ Ag $\rm_{x}$($\rm{x}=$ 0.25,0.50,0.75)合金的FCC结构被认为是本研究中的燃料电池组件。我们已经研究了它作为燃料电池组件的质量,看看它是否可以作为Pt催化剂的替代品。用密度泛函理论研究了H和CO与表面的相互作用,用动力学Monte Carlo~(KMC)研究了H和CO从表面的脱附。采用GPAW程序,在平面波基组$\&$中,采用PBE交换相关处理,计算了Pd $\rm_{1-x}$ Ag $\rm_{x}$合金的体弹性模量和平衡晶体结构.晶格常数的最佳值的系统得到的总能量计算与晶格细胞体积拟合稳定的jeldom模型。计算了Pd $\rm_{1-x}$ Ag $\rm_{x}$合金的表面能、结合能和结合能,分析了合金结构的稳定性。能带结构计算揭示了这些合金的电子和光学性质。态密度~(DOS)和投影态密度~(PDOS)表明了本征态的有效性。脱附过程中进行了研究,在阿克里纽斯型脱附速率$\&$的温度程序。考虑了吸附分子间的横向相互作用对一级脱附(分子吸附)$\&$二级脱附的影响。用密度泛函理论计算了H和CO在Pd $\rm_3$ Ag~(111)上的吸附能。结果显示与文献的定性一致。

英文摘要:

The FCC structure of Pd$\rm_{1-x}$Ag$\rm_{x}$ ($\rm{x}=$ 0.25, 0.50, 0.75) alloys is considered as a fuel cell component in this study. We have looked into its qualities as a component of a fuel cell to see whether it could be potentially used as an alternative replacement of the Pt catalyst. We used Density Functional Theory (DFT) to study H and CO interaction with the surface, and Kinetic Monte Carlo~(KMC) to study H and CO desorption from the surface. The bulk modulus and equilibrium crystal structures of Pd$\rm_{1-x}$Ag$\rm_{x}$ alloys were computed using the GPAW code within plane wave basis set $\&$ a PBE exchange correlation functional treatment. The best values of a lattice constant for the system are obtained by total energy calculations versus lattice cell volumes as fitted to the stabilized jellium model. Surface energies, cohesive energies, and\ binding energy of Pd$\rm_{1-x}$Ag$\rm_{x}$ alloys were computed to analyze the stability properties of structures. Band structure calculations reveal the electronic and optical properties of these alloys. The density of states~(DOS) and projected density of states~(PDOS) show the availability of the eigenstates for occupation. The desorption process is studied within the Arrhenius type desorption rate $\&$ a temperature programming. The effects of lateral interactions between adsorbed molecules on first order desorption (molecular adsorption) $\&$ second order desorption were taken into account. Adsorption energies of H and CO on Pd$\rm_3$Ag~(111) as calculated using DFT is used in the process. The outcomes show good qualitative agreement with literature.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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