Abstract Organophosphonic acid surface modification is performed to alter the surface properties of titania or other ceramics. By changing the modification conditions the physicochemical properties of the surface can be controlled. While these changes have been studied on the macroscale for different functional groups, showing differences in sorption behavior and application, their local impact on the surface OH-groups and resulting interaction with water is still unclear. Hence, we report an in-depth in-situ IR investigation supported by quantum chemical calculations and focused on the states of adsorbed water and the surface OH-groups of organophosphonic acid modified P25. Infrared spectra are recorded from fully saturated to fully dehydrated state by systematic desorption in vacuum and in function of temperature. Interesting differences in water desorption/interaction behavior for propylphosphonic acid modified titania are revealed, in which not only the number of grafted groups but also their distribution influences (the strength of) the interaction with water. Furthermore, when modifying with phenylphosphonic acid, additional water interactions in between the aromatic rings, could be observed. Finally, an interesting difference in thermal behavior of surface hydroxyl condensation could be observed for the modified surfaces. In contrast to pristine P25, they still feature surface hydroxyl groups at 250 °C.

中文翻译：

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水与有机膦酸表面改性二氧化钛的相互作用：深入的原位漂移研究

摘要 有机膦酸表面改性是为了改变二氧化钛或其他陶瓷的表面性质。通过改变改性条件，可以控制表面的物理化学性质。虽然已经在宏观尺度上研究了不同官能团的这些变化，显示出吸附行为和应用的差异，但它们对表面 OH 基团的局部影响以及由此产生的与水的相互作用仍不清楚。因此，我们报告了由量子化学计算支持的深入原位 IR 研究，重点是吸附水的状态和有机膦酸修饰的 P25 的表面 OH 基团。通过真空中的系统解吸和温度函数记录从完全饱和到完全脱水状态的红外光谱。揭示了丙基膦酸改性二氧化钛的水解吸/相互作用行为的有趣差异，其中不仅接枝基团的数量而且它们的分布影响与水的相互作用（强度）。此外，当用苯基膦酸改性时，可以观察到芳环之间的额外水相互作用。最后，可以观察到改性表面的表面羟基缩合热行为的有趣差异。与原始 P25 相比，它们在 250 °C 时仍具有表面羟基。当用苯基膦酸改性时，可以观察到芳环之间的额外水相互作用。最后，可以观察到改性表面的表面羟基缩合热行为的有趣差异。与原始 P25 相比，它们在 250 °C 时仍具有表面羟基。当用苯基膦酸改性时，可以观察到芳环之间的额外水相互作用。最后，可以观察到改性表面的表面羟基缩合热行为的有趣差异。与原始 P25 相比，它们在 250 °C 时仍具有表面羟基。