Nucleation and Initial Stages of Growth during the Atomic Layer Deposition of Titanium Oxide on Mesoporous Silica
Nucleation and Initial Stages of Growth during the Atomic Layer Deposition of Titanium Oxide on Mesoporous Silica
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DOI：
10.1021/acs.nanolett.0c02990
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发表时间：
2020-09-09
期刊：
影响因子：
10.8
通讯作者：
Zaera, Francisco
中科院分区：
文献类型：
--
作者：
Ke, Wang;Liu, Yang;Zaera, Francisco
在固体表面上沉积薄膜的化学方法是非常理想的，但容易影响膜的最终性质。为了更好地理解这些并发症的起源，二氧化钛膜的原子层沉积在二氧化硅介孔材料的初始阶段的特征。吸附-脱附测量表明，膜生长在一个层一层的方式，如所期望的，但最初表现出令人惊讶的低密度，约四分之一的散装氧化钛。电子显微镜，X-射线衍射，UV/可见光，和X-射线吸收光谱数据指向的第一单层的无定形性质，和EXAFS和29 Si CP/MAS NMR结果通过形成独立的四面体钛氧化物单元上孤立的Si-OH表面基团与异常长的Ti-O键的初始增长。密度泛函理论计算被用来提出一种机制，其中的薄膜生长开始在成核中心，形成一个开放的二维结构。
A chemical approach to the deposition of thin films on solid surfaces is highly desirable but prone to affect the final properties of the film. To better understand the origin of these complications, the initial stages of the atomic layer deposition of titania films on silica mesoporous materials were characterized. Adsorption-desorption measurements indicated that the films grow in a layer-by-layer fashion, as desired, but initially exhibit surprisingly low densities, about one-quarter of that of bulk titanium oxide. Electron microscopy, X-ray diffraction, UV/visible, and X-ray absorption spectroscopy data pointed to the amorphous nature of the first monolayers, and EXAFS and 29Si CP/MAS NMR results to an initial growth via the formation of individual tetrahedral Ti-oxide units on isolated Si-OH surface groups with unusually long Ti-O bonds. Density functional theory calculations were used to propose a mechanism where the film growth starts at the nucleation centers to form an open 2D structure.