Faculty of Sciences, Division of Physics and Astronomy, VU University, De Boelelaan 1081 1081 HV Amsterdam, The Netherlands.
4th Physics Institute and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 57 70569 Stuttgart, Germany.
Nat Mater. 2016 Mar;15(3):311-7. doi: 10.1038/nmat4480. Epub 2015 Nov 16.
Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and nanoparticles have recently been published. Although each article provides for the first time detailed data on specific aspects of hydrogen in nanoparticles, they individually do not contain enough information to draw firm conclusions about the involved mechanisms. Here, we show that the large body of data available so far in literature exhibits general patterns that lead to unambiguous conclusions about the processes involved in H absorption and desorption in Pd nanoparticles. On the basis of a remarkably robust scaling law for the hysteresis in absorption-desorption isotherms, we show that hydrogen absorption in palladium nanoparticles is consistent with a coherent interface model and is thus clearly different from bulk Pd behaviour. However, H desorption occurs fully coherently only for small nanoparticles (typically smaller than 50 nm) at temperatures sufficiently close to the critical temperature. For larger particles it is partially incoherent, as in bulk, where dilute α-PdHx and high concentration β-PdHx phases coexist.
钯-氢是一个典型的金属-氢体系。因此，人们对纳米钯颗粒中氢的吸收和释放给予了大量关注，这一点毫不奇怪。最近已经有几篇关于 H 与 Pd 纳米立方体和纳米颗粒相互作用的重要文章发表。尽管每篇文章都首次提供了关于纳米颗粒中氢的特定方面的详细数据，但它们各自提供的信息不足以就所涉及的机制得出明确的结论。在这里，我们表明，到目前为止，文献中提供的大量数据表现出一般模式，这些模式导致了关于 Pd 纳米颗粒中氢吸收和释放所涉及过程的明确结论。基于对吸收-解吸等温线滞后的显著稳健的标度定律，我们表明，钯纳米颗粒中的氢吸收与相干界面模型一致，因此与体 Pd 的行为明显不同。然而，只有在温度足够接近临界温度时，对于小的纳米颗粒（通常小于 50nm），H 解吸才完全是相干的。对于较大的颗粒，它部分是非相干的，就像在体相中一样，其中存在稀有的 α-PdHx 和高浓度的 β-PdHx 相共存。
