H₂ chemisorption measurements are used to estimate the size of supported metal particles, often using a hydrogen‐to‐surface‐metal stoichiometry of unity. This technique is most useful for small particles whose sizes are difficult to estimate through electron microscopy or X‐ray diffraction. Undercoordinated metal atoms at the edges and corners of particles, however, make up large fractions of small metal clusters, and can accommodate multiple hydrogen atoms leading to coverages which exceed 1 ML (supra‐monolayer). Density functional theory was used to calculate hydrogen adsorption energies on Pt and Ir particles (38–586 atoms, 0.8–2.4 nm) at high coverages (≤3.63 ML). Calculated differential binding energies confirm that Pt and Ir (111) single‐crystal surfaces saturate at 1 ML; however, Pt and Ir clusters saturate at supra‐monolayer coverages as large as 2.9 ML. Correlations between particle size and saturation coverage are provided that improve particle size estimates from H₂ chemisorption for Pt‐group metals. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3109–3120, 2018

中文翻译：

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超小金属团簇的超单层覆盖及其对H2化学吸附粒径估计的影响

高₂化学吸附测量通常用于氢-表面-金属化学计量单位的估计，以估计负载的金属颗粒的大小。对于难以通过电子显微镜或X射线衍射估算尺寸的小颗粒，此技术最有用。但是，颗粒边缘和角落的配位不足的金属原子占小部分金属簇的大部分，并且可以容纳多个氢原子，导致覆盖率超过1 ML（超单层）。密度泛函理论用于计算高覆盖率（≤3.63ML）的Pt和Ir粒子（38-586个原子，0.8-2.4 nm）上的氢吸附能。计算出的微分结合能证实Pt和Ir（111）单晶表面在1 ML时饱和；然而，Pt和Ir团簇在超单层覆盖范围达到2.9 ML时会饱和。提供了粒径和饱和度覆盖率之间的相关性，从而改善了从H估算粒径₂铂族金属的化学吸附。©2018美国化学工程师学会AIChE J，64：3109-3120，2018