abstract

• CeO2 nanotubes (NT) were synthesized via a hydrothermal method, employing two different alkaline bases, NaOH, and KOH, to obtain NTNaOH-CeO2 and NTKOH-CeO2. The as-produced NTNaOH-CeO2 and NTKOH-CeO2 were heated in air to study their morphological evolution and characterize the influence of morphology on their photocatalytic activities. Two morphological changes were observed, from NTNaOH-CeO2 and NTKOH-CeO2 nanotubes at room temperature to nanobars at temperatures starting from 375 °C, followed by a recrystallization of these at 550 °C and above. These transformations correspond to irreversible structural modifications that changed the morphological and optical properties as characterized by a high-resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), IR spectra, temperature-dependent Raman spectroscopy, thermo-gravimetric analysis (TGA), and photocatalytic activity. Higher temperatures produced significantly lower wavenumber shifts in the Raman band spectra of NTNaOH-CeO2 and NTKOH-CeO2. The dominant F2g phonon exhibited monotonic lower wavenumber shifts with increasing temperatures. A discontinuity on the phonon broadening for NTKOH-CeO2 was observed around 345 °C. The post-temperature HR-TEM and Raman analysis confirmed the changes in the morphology of both NTNaOH-CeO2 and NTKOH-CeO2, collapsing from nanotubes to nanobars (NB). The phonon softening%27s linewidths and lifetimes were analyzed using a model that considered four anharmonic processes. The study of the photocatalytic response of NTNaOH-CeO2 and NTKOH-CeO2 calcined at 850 °C (with the morphology transformation from NT to NB), which resulted in the prepared material presenting superior catalytic activity when compared with commercial non-stoichiometric CeO2, having activities up to two orders of magnitude faster than similar compounds reported in the literature. The so-prepared and calcined NTMOH-CeO2 (M = K or Na) NB has potential applications in water remediation to degrade textile dyes, which are found as contaminants in water wastage in this industry. © 2022 Elsevier Ltd and Techna Group S.r.l.

authors

• Alanis J.
• Mendoza-Mendoza E.
• Navarro Contreras Hugo Ricardo
• Ojeda-Galván H.J.
• Quintana Ruiz Mildred
• Rodríguez Aranda Ma. del Carmen
• Rodríguez Vázquez Ángel Gabriel
• Ulloa-Castillo N.A.
• Villabona-Leal E.G.

publication date

• 2022-01-01

funding provided via

• CONACYT proyecto Mantenimiento de Infraestructura Científica de Laboratorios Nacionales 2020-314931 , 2021-315911 , CB-2016-285350 , CB-A1-S-8817 . The authors thank the access and use of the equipment at the Laboratorio Nacional de Análisis Físicos, Químicos y Biológicos-UASLP. E. Mendoza thanks “Cátedras-CONACYT program” through project 864. H. Ojeda, J. Alanis and E. Villabona thank “Estancias Posdoctorales por Mexico 2021-Conacyt program”. The Authors thank Sergio Negrete for the support in the laboratory.  Grant

published in

• Ceramics International  Journal

keywords

• Calcination; CeO2; Photocatalysis Calcination; Morphology; Nanotubes; Optical properties; Photocatalytic activity; Potassium hydroxide; Sodium hydroxide; Thermogravimetric analysis; Alkalines; Hydrothermal methods; Hydrothermally synthesized; Morphological changes; Morphological evolution; Nanobars; Photocatalytic application; Synthesised; Thermal tuning; Wavenumber shifts; Cerium oxide

Digital Object Identifier (DOI)

• 10.1016/j.ceramint.2022.03.051

PubMed ID

start page

• 17802

end page

• 17815

volume

• 48

issue

• 12