Abstract
TiO2/SnO2 composites have attracted considerable attention for their application in photocatalysis, fuel cells and sensors. Structural, morphological, optical and surface features play a pivotal role in photoelectrochemical applications and are critically related to the synthetic route. Most of the reported synthetic procedures require high-temperature treatments in order to tailor the sample crystallinity, usually at the expense of surface hydroxylation and morphology. In this work, we investigate the role of a treatment in an autoclave at a low temperature (100°C) on the sample properties and photocatalytic performance. With respect to samples calcined at 400°C, the milder crystallization treatment promotes anatase phase, mesoporosity and water chemi/physisorption, while reducing the incorporation of heteroatoms within the TiO2 lattice. The role of Sn content was also investigated, showing a marked influence, especially on the structural properties. Notably, at a high content, Sn favours the formation of rutile TiO2 at very low reaction temperatures (100°C), thanks to the structural compatibility with cassiterite SnO2. Selected samples were tested towards the photocatalytic degradation of tetracycline in water under UV light. Overall, the low-temperature treatment enables to tune the TiO2 phase composition while maintaining its surface hydrophilicity and gives rise to well-dispersed SnO2 at the TiO2 surface.
Highlights
TiO2/SnO2 composites find application in numerous cutting-edge fields, such as fuel cells [1], gas sensors [2,3] and photocatalysis [4,5]
We investigate the role of a treatment in an autoclave at a low temperature (1008C) on the sample properties and photocatalytic performance
We investigated the role played by a prolonged treatment (170 h) at a mild temperature (1008C) in an autoclave on the structural, morphological, optical and surface properties of TiO2/SnO2 composites prepared by a sol–gel procedure
Summary
TiO2/SnO2 composites find application in numerous cutting-edge fields, such as fuel cells [1], gas sensors [2,3] and photocatalysis [4,5]. The different work functions of the two oxides (4.9 and 4.2 eV for SnO2 and TiO2, respectively [8]) favour the occurrence of electron transfer from the TiO2 conduction band to the SnO2 one, giving rise to a contact potential at the interface [9] This phenomenon is highly desirable in photoelectrochemical applications, such as photocatalysis [10], as it enhances charge carrier separation and, as a result, the device efficiency. Lowtemperature crystal growths require less energy and can be performed in situ on a broad range of process-compatible materials, including heat-sensitive materials such as polymers Such mild treatments can enhance the final properties of the prepared materials like the structural composition, morphology and surface hydroxylation. Surface hydroxyl groups can trap holes and hinder charge recombination [25]
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