Conjugated Polymer Modifying TiO2 Performance for Visible-Light Photodegradation of Organics

Abstract

Up to now, the use of TiO2 has been considered a promising advanced technology for organic pollutants removal from air or water, since it has high biological and chemical stability, high photoactivity, low toxicity, and low-cost production. However, there are issues to be addressed in enhancing TiO2 performance, and one of the current key issues is redesigning UV-active photocatalysts and making them active in the visible region of the electromagnetic spectrum. This way, solar light absorption will be insured, and thus, a more efficient photocatalyst could be obtained. For this reason, conjugated polymers and their derivatives are considered to act as photosensitizers, being able to shift the TiO2 activity from the UV to the visible region. Therefore, this study focuses on the synthesis of TiO2/conjugated polymer systems, which was accomplished by the deposition of poly-3,4-ethylene-dioxy-thiophene (PEDOT [-C6H4O2S-]n), a low-band semiconductor with an excellent stability due to its extending π-conjugated electron system, on titania nanoarchitecture. First of all, a TiO2 nanoarchitecture was synthesized by an ultrasound-assisted sol–gel method. Then, TiO2/PEDOT systems were obtained and characterized by using different techniques such as X-ray diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, UV–Vis diffuse reflectance, and N2 sorption measurements. The synthesized composites confirmed their mesoporosity and lower band gap values compared to bare titania, which clearly shows the ability to work as photocatalysts under visible-light activity. Further, we demonstrated that an organic pollutant, Congo Red dye, used as a model molecule could be photodegraded with the synthesized TiO2/PEDOT systems, with efficiencies of up to 95% in the case of TconvPEDOT under UV light and up to 99% for TconvPEDOT under visible-light irradiation, accomplishing in this way a successful synthesis of visible-light-activated titania photocatalyst.

Positional Isomeric Effects on the Physicochemical Properties of Polymeric Matrix and Polymer@TiO2 Nanocomposites

“…Over the past decades, semiconductor photocatalysis has attracted considerable attention as an affordable and uncomplicated technology for wastewater treatment. Thus, extensive research has been conducted on nanostructured metal-oxide (MO) semiconductors such as TiO 2 [8,9]. Despite being one of the more commonly employed photocatalytic materials [10], TiO 2 has a relatively wide band gap ranging from 3.0 to 3.3 eV [8,11].…”

“…Thus, extensive research has been conducted on nanostructured metal-oxide (MO) semiconductors such as TiO 2 [8,9]. Despite being one of the more commonly employed photocatalytic materials [10], TiO 2 has a relatively wide band gap ranging from 3.0 to 3.3 eV [8,11]. As a result, bare TiO 2 only exhibits photoactivity under UV excitation, making it a disadvantage from this perspective.…”

“…For this reason, researchers are exploring and developing TiO 2 -based photocatalyst systems with an improved visible-light response [10,11]. This effect has been obtained by coupling conducting polymers (PCs) with TiO 2 photocatalysts, improving TiO 2 photocatalytic efficiency [8,12]. However, conjugated polymers and their derivatives can act as photosensitizers and have shown excellent stability due to their extending π-conjugated electron systems.…”

Oxygen Vacancies Defective La2Ti2O7 Nanosheets Enhanced Photocatalytic Activity of Hydrogen Evolution under Visible Light Irradiation

“…Also, its ionic character at room temperature impairs carrier transport and diminishes the efficiency of charge carrier separation. To circumvent these issues, numerous attempts have been made to broaden the photo-absorption of La 2 Ti 2 O 7 , using methods like doping and amalgamation with another semiconductor [30][31][32][33][34][35]. Despite these efforts, the widespread application of La 2 Ti 2 O 7 remains significantly constrained due to the high recombination rate of photogenerated electron-hole pairs.…”