Soft-templated mesostructured TiO2 - SiO2 composites with high thermal stability

• Published in: Microporous and mesoporous materials 2024-01, Vol.364, p.112851, Article 112851
• Main Authors: Lebeau, Bénédicte, Jonas, Florian, Michelin, Laure, Blin, Jean-Luc
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Glass effect; Material chemistry; Mesostructured titania; Phase transformation; Photo-discoloration; Soft templating
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2023.112851

To overcome the drawbacks of pure mesostructured titania and in particular the low thermal stability, in this study we have investigated in detail the effect of Si4+ addition on the properties of mesostructured TiO2 prepared by combining the sol-gel process and the surfactant templating mechanism. Obtained materials have also been tested for the photodegradation of methyl orange, used as a model dye. From the SAXS and the manometry nitrogen adsorption-desorption analyses, it can be concluded that the presence of Si4+ delays the collapse of the mesopores network. Compared to the bare mesostructured TiO2, the XRD and Raman results show that the anatase and the rutile phases appear at higher temperature. The higher the Si4+ content, the higher the amorphous-anatase and rutile anatase-phase transition temperatures. The delay in the crystallization also allows the detection of the TiO2-β phase, which is an anatase phase with oxygen vacancies. These phenomena have been attributed to the « glass effect ». In that case, amorphous SiO2, which is formed during the synthesis, surrounds the titania particles and inhibits their growth, when the heating temperature is increased. By this way, the thermal stability of the mesostructured titania containing Si4+ is enhanced. Photocatalytic experiments highlight the importance of the presence of the anatase phase for the discoloration efficiency of the dye solution. Indeed, the increase of Si4+ leads to a clear decrease of the photodegradation efficiency. [Display omitted] •Presence of SiO2 involves an enhancement of thermal stability.•Protector role of amorphous SiO2 surrounding TiO2 particles.•Stabilization of TiO2-β and inhibition of rutile occur in the presence of SiO2.•Partial substitution of Ti4+ by Si4+.•Discoloration rate of the dye solution correlated to the size of the anatase crystallites.