Titanate nanofibers sensitized with ZnS and Ag2S nanoparticles as novel photocatalysts for phenol removal

- Novel Ag2S-ZnS/TNF nanocomposite materials with different layouts were prepared.
- Photocatalytic performance of Ag2S-ZnS/TNF powders to phenol removal was studied.
- Ag2S(ZnS/TNF) was the sample with the best activity for phenol photodegradation.
- Two energetic mechanisms for Ag2S/TNF and Ag2S(ZnS/TNF) performance were proposed.

In this work, the synthesis of new nanocomposite materials, with enhanced optical and photocatalytic properties, was achieved through the combination of photoactive titanate nanofibers (TNF) with crystalline ZnS and Ag2S nanoparticles. The TNF powders were obtained via hydrothermal synthesis and afterwards modified with the semiconductor nanoparticles. The Ag2S and ZnS nanocrystallites were successfully grown onto the TNF surface, through a single-source precursor decomposition method, and ZnS-Ag2S/TNF nanocomposite materials with distinct layouts were produced. After structural, morphological and optical characterization, the samples' photocatalytic performance to hydroxyl radical production was evaluated using terephthalic acid as probe molecule. The nanocomposite powders were investigated for phenol removal, while the identification and the time profiles of some by-products formed during the phenol degradation were carefully analysed.Results suggest distinct photocatalytic pathways for the production of hydroxyl radical, as well as distinct phenol degradation mechanisms. The phenomenon was found to be dependent on the semiconductors layout. Ag2S(ZnS/TNF) was the sample with the best photocatalytic activity, in terms of phenol removal and also considering the amount of by-products formed and time required for their degradation. Based on the photocatalytic degradation results, two energetic mechanisms for Ag2S/TNF and Ag2S(ZnS/TNF) performance were proposed and discussed.

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