Novel C-dots/titanate nanotubular hybrid materials with enhanced optical and photocatalytic properties (2201.08243v2)

Abstract: Advanced nanomaterials with enhanced optical and photocatalytic properties for the photodegradation of organic pollutants, in particular pharmaceuticals and personal care products (PPCPs), were successfully prepared by a swift one-pot synthesis. Nanostructured materials were synthesized through an integrated hydrothermal procedure which generates titanate nanotubes (TNTs) with different carbon dots (C-dots) contents, from an amorphous titanium oxide-based source and cork industry wastewaters (CIWWs) as carbon source. Their structural, microstructural, morphological, and optical properties were studied by XRD, TEM, UV-Vis diffuse reflectance and photoluminescence spectroscopies. As aimed, the hybrid C-dots/TNT nanomaterials extend their light absorption towards the red, in comparison to pristine TNTs, prompting them for a more efficient use of light in photocatalysis by widening the TNTs energy uptake range. The decrease of bandgap energy with increasing sample's C-dots content seems to be originated from energy intermediate states formed within the TNTs forbidden band resulting from Ti-O-C bonds established between the TNTs and the C-dots that form tails of states. The as-synthesized C-dots/TNT samples were tested in the photodegradation of caffeine as a pollutant model. Rewarding results were obtained, with the hybrid C-dots/TNT nanomaterials showing significant enhanced photocatalytic ability toward caffeine degradation in comparison to pristine TNTs. Photocatalysis assays in the presence of scavengers and/or in the absence of oxygen were also performed aiming to characterize the most reactive species formed during the semiconductor photo-activation process and thus assessing to possible reactive pathways underpinning the photocatalytic activity of the hybrid C-dots/TNT nanomaterials.