Abstract

The adsorption of CO molecules by Pt and Pt–Sn nanoparticles is studied using ab initio calculations. The Pt–C and C–O bond lengths, adsorption energies, and stretching frequencies of adsorbed molecules on the surface of nanoparticles at different sites are calculated. The calculated values are in good agreement with the experimental data. The segregation of bimetallic nanoparticles is also observed. The configuration of a nanoparticle in which platinum atoms are in the nucleus and tin atoms are on the surface is found to be energetically most favorable. The effect of Sn atoms near Pt on the density of electronic states of platinum and the stretching frequency of adsorbed CO molecules is also studied. Tin in the first coordination sphere is found to decrease the CO stretching frequency. The results obtained will allow quantitative interpretation of the infrared spectra of bimetallic nanoparticles during the catalytic reaction to analyze the surface morphology. The constructed adsorption energy maps will make it possible to predict the occupancy of nonequivalent adsorption sites at different temperatures and gas pressures.

中文翻译：

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PtSn双金属纳米粒子上CO分子的结合能和拉伸频率的理论模拟

摘要

使用从头算计算研究了Pt和Pt-Sn纳米颗粒对CO分子的吸附。计算了不同位置的纳米颗粒表面上的Pt–C和C–O键长，吸附能和吸附分子的拉伸频率。计算值与实验数据吻合良好。还观察到双金属纳米颗粒的偏析。发现在能量上最有利的是纳米颗粒的构型，其中铂原子在原子核中，而锡原子在表面。还研究了Pt附近的Sn原子对铂的电子态密度和吸附的CO分子的拉伸频率的影响。发现第一配位球中的锡降低了CO的拉伸频率。获得的结果将能够定量解释双金属纳米颗粒在催化反应期间的红外光谱，以分析表面形态。所构建的吸附能图将使预测不同温度和气压下非等价吸附位点的占据成为可能。