Adsorption of methylamine on mackinawite (FES) surfaces: a density functional theory study.
Adsorption of methylamine on mackinawite (FES) surfaces: a density functional theory study.
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DOI：
10.1063/1.4822040
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发表时间：
2013-09
期刊：
影响因子：
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通讯作者：
N. Dzade;A. Roldan;N. H. Leeuw
中科院分区：
文献类型：
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作者：
N. Dzade;A. Roldan;N. H. Leeuw
采用密度泛函理论（DFT）方法研究了甲胺（CH 3 NH 2）与硫铁矿（FeS）表面的相互作用，并采用格里姆的DFT-D2方法研究了硫铁矿的表面性质和吸附性质.我们的计算表明，虽然CH 3 NH 2分子仅与最稳定的FeS（001）弱相互作用，但它在FeS（011）和FeS（100）表面上的吸附相对较强，释放的能量分别为1.26 eV和1.51 eV。键合性质的分析表明，CH 3 NH 2分子通过位于N原子上的孤对电子与mackinawite表面相互作用。在N和Fe之间的键合区域中建立的电子密度非常接近人们对共价键合类型的期望。我们没有观察到显着的吸附诱导的FeS表面结构的变化，这表明胺封端剂不会扭曲活性多相催化反应所需的FeS纳米粒子表面。计算了甲胺吸附的振动频率和红外光谱，并对振动模式进行了归属，提出了脱附过程的动力学模型，模拟了程序升温脱附过程，其相对脱附温度在FeS（011）面<140 K，在FeS（100）面<170 K.
We have used density functional theory calculations to investigate the interaction between methylamine (CH3NH2) and the dominant surfaces of mackinawite (FeS), where the surface and adsorption properties of mackinawite have been characterized using the DFT-D2 method of Grimme. Our calculations show that while the CH3NH2 molecule only interacts weakly with the most stable FeS(001), it adsorbs relatively strongly on the FeS(011) and FeS(100) surfaces releasing energies of 1.26 eV and 1.51 eV, respectively. Analysis of the nature of the bonding reveals that the CH3NH2 molecule interacts with the mackinawite surfaces through the lone-pair of electrons located on the N atom. The electron density built up in the bonding region between N and Fe is very much what one would expect of covalent type of bonding. We observe no significant adsorption-induced changes of the FeS surface structures, suggesting that amine capping agents would not distort the FeS nanoparticle surfaces required for active heterogeneous catalytic reactions. The vibrational frequencies and the infrared spectra of adsorbed methylamine have been calculated and assignments for vibrational modes are used to propose a kinetic model for the desorption process, yielding a simulated temperature programmed desorption with a relative desorption temperature of <140 K at the FeS(011) surface and <170 K at FeS(100) surface.