In situ X-ray absorption spectroscopy has afforded detailed structural and electronic characterization of a newly developed stabilized Pt-skin/PtCo alloy nanoparticle catalyst for CO-tolerant H₂ oxidation. The X-ray absorption near-edge structure (XANES) results show the significant effects of H and CO adsorption on white lines for pure Pt nanoparticles, which are correlated with the depletion of the density of states (DOS) just below the Fermi level (FL) calculated with density-functional theory (DFT). In contrast, for the Pt-skin/PtCo surface, there is little effect on the XANES for either H or CO adsorption. The lack of effect is consistent with the lack of variation of the DOS near the FL. The extended X-ray absorption fine structure (EXAFS) results for pure Pt nanoparticles have exhibited significant changes caused by H and CO adsorption. Such changes are suggested to be associated with the selected surface expansion of Pt atoms, as revealed from DFT-calculated radial distribution functions (RDFs). In contrast, for the Pt-skin/PtCo surface, there were negligible changes in the EXAFS, either with H or CO adsorption, which is consistent with the lack of changes in the DFT-calculated RDF. Notably, the rigidity of the Pt skin and the lower degree of overlap between Pt and CO orbitals, due to the narrowing of the d-band, are thought to be responsible for the weak adsorption.

中文翻译：

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原位X射线吸收光谱法 分析的稳定的Pt皮/ PtCo氢氧化催​​化剂对CO的吸附减弱且结构完整性增强†

原位X射线吸收光谱学提供了一种新开发的用于CO耐受H _2的稳定化的Pt-皮肤/ PtCo合金纳米颗粒催化剂的详细结构和电子表征氧化。X射线吸收近边缘结构（XANES）的结果表明，纯Pt纳米颗粒的白线上的H和CO吸附具有显着影响，这与刚好在费米能级以下的状态密度（DOS）的消耗相关（ FL）是根据密度泛函理论（DFT）计算得出的。相反，对于Pt皮肤/ PtCo表面，无论是H还是CO吸附，对XANES的影响都很小。缺乏效果与FL附近DOS缺乏变化相一致。纯Pt纳米粒子的扩展X射线吸收精细结构（EXAFS）结果显示出由H和CO吸附引起的显着变化。从DFT计算的径向分布函数（RDFs）可以看出，这种变化被认为与选定的Pt原子表面扩展有关。相比之下，对于Pt皮肤/ PtCo表面，无论是H还是CO吸附，EXAFS的变化都可以忽略不计，这与DFT计算的RDF缺乏变化是一致的。值得注意的是，由于d带的变窄，Pt蒙皮的刚度以及Pt和CO轨道之间较低的重叠度被认为是造成弱吸附的原因。