首页> 外文期刊>Chemistry: A European journal >Structure-Dependent Anchoring of Organic Molecules to Atomically Defined Oxide Surfaces: Phthalic Acid on Co3O4(111), CoO(100), and CoO(111)
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Structure-Dependent Anchoring of Organic Molecules to Atomically Defined Oxide Surfaces: Phthalic Acid on Co3O4(111), CoO(100), and CoO(111)

机译:有机分子对原子定义的氧化物表面的结构依赖性固定:Co3O4(111),CoO(100)和CoO(111)上的邻苯二甲酸

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We have performed a model study to explore the influence of surface structure on the anchoring of organic molecules on oxide materials. Specifically, we have investigated the adsorption of phthalic acid (PA) on three different, well-ordered, and atomically defined cobalt oxide surfaces, namely 1)Co3O4(111), 2)CoO(111), and 3)CoO(100) on Ir(100). PA was deposited by physical vapor deposition (PVD). The formation of the PA films and interfacial reactions were monitored in situ during growth by isothermal time-resolved IR reflection absorption spectroscopy (TR-IRAS) under ultrahigh vacuum (UHV) conditions. We observed a pronounced structure dependence on the three surfaces with three distinctively different binding geometries and characteristic differences depending on the temperature and coverage. 1)PA initially binds to Co3O4(111) through the formation of a chelating bis-carboxylate with the molecular plane oriented perpendicularly to the surface. Similar species were observed both at low temperature (130K) and at room temperature (300K). With increasing exposure, chelating mono-carboxylates became more abundant and partially replaced the bis-carboxylate. 2)PA binds to CoO(100) in the form of a bridging bis-carboxylate for low coverage. Upon prolonged deposition of PA at low temperature, the bis-carboxylates were converted into mono-carboxylate species. In contrast, the bis-carboxylate layer was very stable at 300K. 3)For CoO(111) we observed a temperature-dependent change in the adsorption mechanism. Although PA binds as a mono-carboxylate in a bridging bidentate fashion at low temperature (130K), a strongly distorted bis-carboxylate was formed at 300K, possibly as a result of temperature-dependent restructuring of the surface. The results show that the adsorption geometry of PA depends on the atomic structure of the oxide surface. The structure dependence can be rationalized by the different arrangements of cobalt ions at the three surfaces.
机译:我们进行了模型研究,以探索表面结构对有机分子在氧化物材料上锚固的影响。具体而言,我们研究了邻苯二甲酸(PA)在三个不同的,有序的和原子定义的氧化钴表面上的吸附,即1)Co3O4(111),2)CoO(111)和3)CoO(100)在Ir(100)上。通过物理气相沉积(PVD)沉积PA。在超高真空(UHV)条件下,通过等温时间分辨红外反射吸收光谱(TR-IRAS)在生长过程中就地监测PA膜的形成和界面反应。我们观察到了三个表面上明显的结构依赖性,具有三个明显不同的结合几何形状和取决于温度和覆盖范围的特征差异。 1)PA最初通过形成分子平面垂直于表面的螯合双羧酸与Co3O4(111)结合。在低温(130K)和室温(300K)下都观察到相似的物种。随着暴露量的增加,螯合的单羧酸盐变得更加丰富,并部分取代了双羧酸盐。 2)PA以桥接双羧酸盐的形式与CoO(100)结合,从而降低覆盖率。在低温下长时间沉积PA后,双羧酸盐转化为单羧酸盐。相反,双羧酸盐层在300K时非常稳定。 3)对于CoO(111),我们观察到了吸附机理中温度随温度的变化。尽管PA在低温(130K)下以桥接双齿的形式结合为单羧酸盐,但在300K时会形成严重扭曲的双羧酸盐,这可能是表面依赖于温度的结构重组的结果。结果表明,PA的吸附几何形状取决于氧化物表面的原子结构。可以通过三个表面上钴离子的不同排列来合理化结构依赖性。

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