The interaction of water with organophosphonic acid surface modified titania: An in-depth in-situ DRIFT study

• Published in: Surfaces and interfaces Vol. 21; p. 100710
• Main Authors: Van Dijck, Jeroen G., Lenaerts, Hilde, Siemons, Laurens, Blockhuys, Frank, Meynen, Vera
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-12-2020
• Subjects: In-situ DRIFT; Organophosphonic acids; Surface modification; Titanium dioxide; Water desorption; Surface modification; Water desorption; Organophosphonic acids; Titanium dioxide; In-situ DRIFT
• ISSN: 2468-0230; 2468-0230
• DOI: 10.1016/j.surfin.2020.100710

•Functionalization of TiO2 with Organophosphonic acids.•Functionalization impacts the interaction between the surface and water.•Clear influence of the distribution 3PA is observed, not for PhPA.•Water on modified surfaces can form a hydrogen bridge with organophosphonic acids.•Water can adsorb in between the aromatic rings of PhPA.
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.