Investigate interactions of water with mesoporous ceria using in situ VT-DRIFTS

• Published in: Surface science Vol. 691; p. 121486
• Main Authors: Luo, Lingyiqian, LaCoste, Jed D., Khamidullina, Nuriya G., Fox, Elizabeth, Gang, Daniel D., Hernandez, Rafael, Yan, Hui
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-01-2020; Elsevier BV
• Subjects: Adsorbed water; Adsorption; Cerium oxides; Drift; Fourier transforms; Gas-phase H2O; Hydrogen bonds; Hydroxyl groups; In situ VT-DRIFTS; Nanoparticles; Ordered mesoporous ceria; Spectrum analysis; Surface chemistry; Water vapor; Gas-phase H2O; Ordered mesoporous ceria; Hydroxyl groups; In situ VT-DRIFTS
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2019.121486

•Molecular water and water dissociation coexist on surfaces of ordered mesoporous ceria nanopowder.•Six IR vibrational bands for surface hydroxyls exist on mesoporous ceria at temperature from 25 oC to 400 °C.•Water adsorption on mesoporous ceria is 90% reproducible and active sites for water adsorption are recoverable after 4 cycles of heating from 25 oC to 400 °C in 60 h.
The interactions of water with synthesized mesoporous ceria nanoparticles are studied as a function of temperature at two water vapor partial pressures, using in situ Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS). The Variable Temperature (VT)-DRIFTS spectra of mesoporous ceria nanoparticles exhibit six hydroxyl (OH) stretching bands, suggesting both molecular and dissociation of water coexist on mesoporous ceria surfaces and involve hydrogen-bonds. The vibration frequency of individual OH mode is repeatable and the adsorption of water is reversible on various sites between four annealing and water exposure cycles lasting for 60 h, suggesting that the same types of active sites are available on mesoporous ceria surface for water adsorption, with less than 10% of reduction in the numbers of adsorption sites. The results, from this study of reactivity of water on ordered mesoporous ceria nanoparticles under operando conditions, assist in processes benefiting from the hydroxylated surface for improved reaction outcomes, and rational design of mesoporous materials for their application in photocatalysis and heterogeneous catalysis.
[Display omitted]