Ni（110）上的水离解和羟基形成,The Journal of Physical Chemistry C

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Ni（110）上的水离解和羟基形成
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-10-15 , DOI: 10.1021/acs.jpcc.0c08708
Nikki Gerrard ₁ , Kallum Mistry ₁ , George R. Darling ₁ , Andrew Hodgson ₁

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镍是用于氢化和重整反应的活性催化剂，反应显示出对暴露表面的强烈依赖性。在这里，我们描述了使用扫描隧道显微镜和低电流低能电子衍射在Ni（110）上水离解过程中形成的混合羟基-水相。当H键结构从完整的水的线性一维（1D）链演变为包含短行面共享六边形环的二维（2D）网络时，水的解离开始于150至180K。随着更多的水解吸，六角形排采用局部（2×3）排列，形成由应变消除特征分隔的小的无序区域。该相的分解发生在220 K附近，形成线性的一维结构，该结构由平坦的之字形水链组成，通过将一个H贡献给羟基以形成支链结构来稳定每种水。OH–H_2个O链彼此排斥，饱和层排列成（2 0，1 4）结构，随着进一步的水解吸，该结构在245 K附近分解为OH。讨论了OH / H ₂ O混合相的结构，并与相关Cu（110）表面上的相比较，其差异归因于2D H键网络中由短的Ni晶格间距和强键引起的应变到OH / H ₂ O.

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Water Dissociation and Hydroxyl Formation on Ni(110)

Nickel is an active catalyst for hydrogenation and re-forming reactions, with the reactions showing a strong dependence on the surface exposed. Here, we describe the mixed hydroxyl–water phases formed during water dissociation on Ni(110) using scanning tunneling microscopy and low-current low-energy electron diffraction. Water dissociation starts between 150 and 180 K as the H-bond structure evolves from linear one-dimensional (1D) chains of intact water into a two-dimensional (2D) network containing short rows of face-sharing hexagonal rings. As further water desorbs, the hexagonal rows adopt a local (2 × 3) arrangement, forming small, disordered domains separated by strain relief features. Decomposition of this phase occurs near 220 K to form linear 1D structures consisting of flat, zigzag water chains, with each water stabilized by donating one H to hydroxyl to form a branched chain structure. The OH–H₂O chains repel each other, with the saturation layer ordering into a (2 0, 1 4) structure that decomposes to OH near 245 K as further water desorbs. The structure of the mixed OH/H₂O phases is discussed and contrasted with those found on the related Cu(110) surface, with the differences attributed to strain in the 2D H-bond network caused by the short Ni lattice spacing and strong bond to OH/H₂O.

更新日期：2020-10-30

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