Surface chemistry at the solid–solid interface: mechanically induced reaction pathways of C 8 carboxylic acid monolayers on copper
Surface chemistry at the solid–solid interface: mechanically induced reaction pathways of C 8 carboxylic acid monolayers on copper
复制标题
固-固界面的表面化学：铜上 C 8 羧酸单层的机械诱导反应途径
DOI：
10.1039/d1cp03170h
复制
发表时间：
2021
影响因子：
3.3
通讯作者：
Tysoe, Wilfred T.
中科院分区：
文献类型：
--
作者：
Rana, Resham;Bavisotto, Robert;Hou, Kaiming;Tysoe, Wilfred T.
机械或摩擦化学过程通常是由施加在固-固界面处接触凸起的大压力（约为1gpa）引起的。由于难以探测发生在埋藏界面处的表面化学反应途径，这些摩擦化学过程尚未得到很好的理解。本文详细阐述了7-辛酸和辛酸吸附在铜上的摩擦化学分解的表面反应途径。在超高真空中，通过在表面滑动碳化钨球或硅原子力显微镜（AFM）尖端来测量化学性质，以验证先前的建议，即羧酸末端基（乙烯基与烷基）的性质可能影响其与对表面的结合，从而影响反应速率。羧酸以羧酸的形式与铜底物紧密结合，从而暴露出碳氢化合物的末端。摩擦化学反应速率与烃类末端的性质无关，尽管原子力显微镜测量的拉力和摩擦力不同。摩擦化学反应以与热反应相同的方式开始，由羧酸基倾斜以消除二氧化碳并沉积烷基物质到表面。该反应在约640 K时发生热反应，但在室温下发生摩擦反应，在吸附产物的后续分解途径的速率和选择性上产生显著差异。
Mechano- or tribochemical processes are often induced by the large pressures, of the order of 1 GPa, exerted at contacting asperities at the solid–solid interface. These tribochemical process are not very well understood because of the difficulties of probing surface-chemical reaction pathways occurring at buried interfaces. Here, strategies for following surface reaction pathways in detail are illustrated for the tribochemical decomposition of 7-octenoic and octanoic acid adsorbed on copper. The chemistry was measured in ultrahigh vacuum by sliding either a tungsten carbide ball or a silicon atomic force microscope (AFM) tip over the surface to test a previous proposal that the nature of the terminal group in the carboxylic acid, vinyl versus alkyl, could influence its binding to the counterface, and therefore the reaction rate. The carboxylic acids bind strongly to the copper substrate as carboxylates to expose the hydrocarbon terminus. The tribochemical reaction rate was found to be independent of the nature of the hydrocarbon terminus, although the pull-off and friction forces measured by the AFM were different. The tribochemical reaction is initiated in the same way as the thermal reaction, by the carboxylate group tilting to eliminate carbon dioxide and deposit alkyl species onto the surface. This reaction occurs thermally at ∼640 K, but tribochemically at room temperature, producing significant differences in the rates and selectivities of the subsequent decomposition pathways of the adsorbed products.