Binary TiO₂/reduced graphene oxide nanocomposite for improving methylene blue photodegradation

Abstract

Herein, TiO2/reduced graphene oxide (TiO2/rGO) nanocomposites were fabricated using the hydrothermal method and investigated with the amount of titanium precursors. The binary nanocomposites were characterized by modern analysis method. The adsorption capacity and photocatalyst degradation were performed based on methylene blue. The appropriate as‐prepared material with 1.5 mL TIP contained a large specific surface area (110.549 m2/g) with TiO2 ranging 4‐25 nm homogenously grafting on the rGO surface. The adsorption results were shown in good accordance with the pseudo‐second‐order while the photoreaction kinetics pursued the pseudo‐first‐order with a high‐rate constant. After the adsorption state, the yield reaches 62.1 % and under UV light for 90 min, 96.8 % of MB was efficiently degraded from water media, which showed a more impressive effect as compared with P25 and rGO. Therefore, the use of TiO2/rGO could be applied in the mass‐scale treatment of organic pollutants in wastewater.

Chitosan-Mediated Coupling of MgFe2O4–TiO2 Nanocomposites for Efficient Methylene Blue Photodegradation

“…Comparable to the temperature effect, the relative aggregation of the oxides vastly resulted from the structural change before the chitosan decomposition and/or the crystalline growth that loses the catalytic surface area. 8 Moreover, the photocatalytic degradation of MB is also consistent with the pseudo-first-order model with a high correlation coefficient for all four durations, similar to the kinetic studies of the calcination temperature. Specifically, based on the results in Table S2, upon the efficient calcination treatment at 800 °C, the rate constants of MFO-TiO 2 samples were considerably promoted as compared to the lowest value (0.0393 min −1 ) of the one prepared at 80 °C for 6 h. Along with the acquired good structural and topological characteristics, 2 h is further validated to be the appropriate calcination time for not only the ferrite preparation but also the photocatalytic potential with the highest rate constant of 0.0847 min −1 in the examination.…”

“…In addition, Table demonstrates a significant decrease in the surface area and the porous dimension of MFO-TiO 2 once the controlled calcination temperature was increased from 80 to 800 °C. This is attributed to the vast thermal decomposition of the chitosan carrier that inherently provides the bounding platform for metallic hydroxide and already formed TiO 2 , the octahedral structure of Ti, formation onto polymer matrix . Besides, the higher temperature treatment can also accelerate the matrix breakage and pore collapse, thus initiating the seed conveyance via phase interaction to ferrite and its coupling with TiO 2 .…”

“…This is attributed to the vast thermal decomposition of the chitosan carrier that inherently provides the bounding platform for metallic hydroxide and already formed TiO 2 , the octahedral structure of Ti, formation onto polymer matrix. 8 Besides, the higher temperature treatment can also accelerate the matrix breakage and pore collapse, thus initiating the seed conveyance via phase interaction to ferrite and its coupling with TiO 2 . In other words, although higher surface areas usually correspond with better photocatalytic traits, the recorded large specific surface mainly results from the multilayer chitosan matrix enclosing the MFO-TiO 2 particles, which hinders the photodegradation efficiency upon treatment at a low temperature of 80 °C.…”

“…17 Therefore, coupling TiO 2 with other metallic oxides can potentially narrow the bandgap energy and control the charge transfer process, which can eventually result in better photocatalytic performance. 8,18,19 On the other hand, regarding metallic oxides, ferrite particles have been reported to be ferromagnetic with remarkably low bandgap energy owing to the virtue of their lattices, 20 particularly spinel ferrites (XFe 2 O 4 , where X refers to metal within valency of 2) with outstanding photocatalytic properties under the visible irradiation region. 21 Moreover, the supermagnetic trait of ferrite molecules naturally allows for high recycling capacity after treatment processes, providing a sustainable solution against trace organic pollutants in aquatic media.…”

“…Many nanometal oxide semiconductors such as CuO, ZnO, or Al 2 O 3 exhibit great electrical properties, good photosensitivity, and charge mobility, thus making them promising photocatalysts in various industrial sectors . Among them, titanium dioxide (TiO 2 ) is an outstanding material for phototreatment processes owing to its nontoxicity, high photoactivity, low cost, and chemical stability. − Nevertheless, several limitations, including its rapid electron–hole (e – –h + ) pair recombination rate and relatively large bandgap (3.2 and 3.0 eV for anatase and rutile phases, respectively) due to the ultraviolet range absorption capacity, have restricted the potential of TiO 2 in practical usages. , Currently, several advanced methods have recently been performed to overcome these drawbacks of TiO 2 , namely, combination with others to form nanocomposite, , nonmetal doping, , and surface modification. , Specifically, studies on heterojunction approaches introduce not only a notable photocatalytic enhancement of the resulting material but also solutions to the major disadvantages of each sole precursor . Therefore, coupling TiO 2 with other metallic oxides can potentially narrow the bandgap energy and control the charge transfer process, which can eventually result in better photocatalytic performance. ,, …”