首页> 外文期刊>Chemphyschem: A European journal of chemical physics and physical chemistry >A first-principle calculation of sulfur oxidation on metallic Ni(111) and Pt(111), and bimetallic Ni@Pt(111) and Pt@Ni(111) surfaces
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A first-principle calculation of sulfur oxidation on metallic Ni(111) and Pt(111), and bimetallic Ni@Pt(111) and Pt@Ni(111) surfaces

机译:金属Ni(111)和Pt(111)以及双金属Ni @ Pt(111)和Pt @ Ni(111)表面上硫氧化的第一性原理计算

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摘要

Sulfur, a pollutant known to poison fuel-cell electrodes, generally comes from S-containing species such as hydrogen sulfide (H _2S). The S-containing species become adsorbed on a metal electrode and leave atomic S strongly bound to the metal surface. This surface sulfur is completely removed typically by oxidation with O _2 into gaseous SO _2. According to our DFT calculations, the oxidation of sulfur at 0.25 ML surface sulfur coverage on pure Pt(111) and Ni(111) metal surfaces is exothermic. The barriers to the formation of SO _2 are 0.41 and 1.07 eV, respectively. Various metals combined to form bimetallic surfaces are reported to tune the catalytic capabilities toward some reactions. Our results show that it is more difficult to remove surface sulfur from a Ni@Pt(111) surface with reaction barrier 1.86 eV for SO _2 formation than from a Pt@Ni(111) surface (0.13 eV). This result is in good agreement with the statement that bimetallic surfaces could demonstrate more or less activity than to pure metal surfaces by comparing electronic and structural effects. Furthermore, by calculating the reaction free energies we found that the sulfur oxidation reaction on the Pt@Ni(111) surface exhibits the best spontaneity of SO _2 desorption at either room temperature or high temperatures.
机译:硫是一种已知的会毒害燃料电池电极的污染物,通常来自诸如硫化氢(H _2S)之类的含S物质。含S的物质被吸附在金属电极上,并使原子S牢固地结合在金属表面上。通常通过用O _2氧化成气态SO _2来完全除去该表面硫。根据我们的DFT计算,纯Pt(111)和Ni(111)金属表面上0.25 ML表面硫覆盖下的硫氧化是放热的。 SO _2的形成障碍分别为0.41和1.07 eV。据报道,结合形成双金属表面的各种金属可调节某些反应的催化能力。我们的结果表明,从具有SO_2形成反应势垒1.86 eV的Ni @ Pt(111)表面去除表面硫比从Pt @ Ni(111)表面(0.13 eV)去除困难。该结果与通过比较电子效应和结构效应,双金属表面可显示出比纯金属表面更多或更少的活性的说法非常吻合。此外,通过计算反应自由能,我们发现Pt @ Ni(111)表面上的硫氧化反应在室温或高温下均表现出最佳的SO _2解吸自发性。

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