Dissociative adsorption and linear organization of formic acid on ZnO(10−10) surface
Dissociative adsorption and linear organization of formic acid on ZnO(10−10) surface
复制标题
甲酸在ZnO(10～10)表面的解离吸附和线性组织
DOI：
10.1016/j.jcat.2020.07.026
复制
发表时间：
2020
影响因子：
7.3
通讯作者：
Xiang Shao
中科院分区：
文献类型：
--
作者：
Zhe Li;Hao Yuan;Yuniu Sun;Jiefu Zhang;Zhenyu Li;Xiang Shao
采用低温扫描隧道显微镜（LT-STM）结合密度泛函理论（DFT）研究了甲酸在ZnO（1 0 −1 0）表面的吸附.通过高分辨率STM图像和原位曝光实验，我们清楚地发现，即使在液氮温度下，甲酸吸附后解离。密度泛函理论计算表明，甲酸盐分子具有优先的双齿构型，其分子平面沿[1 −2 1 0]方向沿着取向，而表面羟基具有两种能量相近的锚定位点.在高温下，吸附的分子聚集成完全由甲酸根和羟基组成的短链，并沿着[0 0 0 1]方向取向，最终组装成半单层覆盖的（2 × 2）超结构。仔细检查的缺陷结构的饱和覆盖膜显示存在的单齿吸附状态的甲酸，但具有非常小的概率。这些结果澄清了不同光谱学研究中不一致的命题。此外，甲酸盐物种的优先排序可能会带来新的见解，通过甲酸盐中间体的相关表面反应的理解。
The adsorption of formic acid on a ZnO(1 0 −1 0) surface has been investigated with low temperature scanning tunneling microscopy (LT-STM) in combination with density-functional theory (DFT) calculations. Through high resolution STM images and in-situ exposure experiments we clearly identify that the formic acid dissociates upon adsorption even at liquid nitrogen temperature. DFT calculations reveal a preferential bidentate configuration of the formate species with the molecular plane orientating along the [1 −2 1 0] direction, while the yielded surface hydroxyl has two kinds of anchoring sites with similar energy. At elevated temperature, the adsorbed molecules were found to accumulate into short chains consisting exclusively of formate and hydroxyl and orienting along the [0 0 0 1] direction, which finally assemble into a (2 × 2) superstructure at half monolayer coverage. Careful examination of the defect structure of the saturation coverage film revealed the existence of monodentate adsorption states of formic acid but with very small probability. These results have clarified the inconsistent propositions from different spectroscopic studies. Moreover, the preferential ordering of the formate species may bring fresh insights into the understandings of the related surface reactions through formate intermediates.