Electrically conductive polyaniline sensitized defective-TiO₂for improved visible light photocatalytic and photoelectrochemical performance: a synergistic effect

Abstract

nanocomposites were prepared by the in-situ oxidative polymerization of aniline in the presence of TiO 2 (p-TiO 2 and m-TiO 2 ) nanoparticles followed by sulfonation with fuming sulfuric acid. Defect-induced TiO 2 (m-TiO 2 ) nanoparticles were obtained by an electron beam (EB) treatment of commercial TiO 2 (p-TiO 2 ) nanoparticles. The resulting s-Pani@p-TiO 2 and s-Pani@m-TiO 2 nanocomposites were characterized by UV-visible diffuse absorbance spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Polyaniline (Pani) was dispersed uniformly over the defective m-TiO 2 surface with intimate contact on the interface to act cooperatively with the defects introduced deliberately to achieve remarkably enhanced properties. The s-Pani@m-TiO 2 nanocomposite showed better photocatalytic activity and photoelectrochemical performance than s-Pani@p-TiO 2 under visible light irradiation, which was attributed partly to the sensitizing effect of Pani, the narrowed band gap of m-TiO 2 and the effective interfacial interaction between Pani and m-TiO 2 . The electrical conductivity measured using a four-point probe revealed s-Pani@m-TiO 2 to have much higher conductivity than s-Pani@p-TiO 2 . Therefore, s-Pani@m-TiO 2 may be used for a wide range of applications owing to its higher charge mobility and high photocatalytic activity. The proposed methodology can also be a potential route for the development of nanocomposites via EB treatment and can be commercialized.

Photocatalytic Graphene-TiO2 Thin Films Fabricated by Low-Temperature Ultrasonic Vibration-Assisted Spin and Spray Coating in a Sol-Gel Process

“…The contact angle of water droplets on graphene and graphene-TiO2 films are shown in Figure S5, where it is found that graphene-TiO2 film is highly wetting (small contact angle) and therefore superhydrophilic. This is due to the hydrogen bonding and strong interlinking between Ti-O and unsaturated -O and -OH groups on graphene [12,[40][41][42]. It is known that TiO2 surface is self-cleaning, meaning that it removes the surface dirt, such as organic compounds.…”

Black N/H‐TiO2 Nanoplates with a Flower‐Like Hierarchical Architecture for Photocatalytic Hydrogen Evolution

“…Since the discovery of photoelectric catalytic water splitting on low‐cost, nontoxic, and stable TiO 2 electrodes, various bandengineering strategies have been attempted to narrow the bandgap of TiO 2 to harvest a larger portion of solar energy in the visible light region . Doping with transition metal and/or nonmetal ions, creating structure defects through hydrogenation, surface metallization, and hybridization with low‐bandgap semiconductors have been used as effective strategies . Among these methodologies, N doping has been considered as a promising solution because it can be used to extend the visible light absorption, it has desirable photocatalytic activity, and acceptable level of recombination of photogenerated charge carriers .…”

A Polianilina No Cenário Ambiental: Uma Aborgagem Sobre Fotocatálise Heterogênea

“…As transferên-cias dessas cargas e a formação de sítios oxidantes e redutores também ocorrem de forma similar àquela para UV (Figura 4). [62][63][64][65][66] Em sistemas solares quando uma parcela de radiação UV está presente, ou ainda, com o uso de radiação artificial sem filtros, haverá contribuição de ambos os mecanismos propostos para luz visível e ultravioleta. 13 Os estudos que envolvem apenas luz UV ou visível são importantes justamente porque em sistemas solares ambas estão presentes, e por isso é preciso compreender como os catalisadores formados por PANI respondem a cada uma delas.…”

“…6,14,15,43,52,54,55,61,[75][76][77][78] A determinação da fotocorrente gerada pelo catalisador e a conversão de fóton incidente em corrente (IPCE) também estão relacionadas diretamente com a maior eficiência fotocatalítica de catalisadores compósitos. 9,52,54,66,76,78,79 Deng et al 78 mostraram que catalisador PANI.TiO 2 -microesfera foi capaz de gerar cerca de 0,11 μA cm -2 em fotocorrente e remoção de corantes acima de 95% sob luz visível, enquanto que, apenas TiO 2 -microesfera em torno de 0,03 μA cm -2 e 60 a 70% de remoção de corantes. No estudo feito por Li et al 52 com PANI.TiO 2 -nanotubos na remoção de rodamina b sob luz visível, dentre todos os materiais sintetizados, aquele com maior geração de fotocorrente (6 μA cm -2 ) promoveu maior remoção do corante, cerca de 90%.…”

“…11 Conforme já citado anteriormente, nesse caso, a luz UV também promove transferên-cias de carga no óxido metálico semicondutor (Figura 4), gerando maior densidade de corrente e espécies reativas, o que se traduz em melhores condições cinéticas e remoção de contaminante. 13,43,60,61,66 Portanto, sob luz UV, a contribuição do óxido metálico é significativa no desempenho fotocatalítico. Essa observação foi demonstrada por Zhang, Zong e Zhu, 54 quando obtiveram aproximadamente 8 vezes mais fotocorrente pelo catalisador PANI.ZnO (suportado em ITOindium tin oxide) sob luz UV em relação àquela obtida sob luz visível.…”