Reduced-graphene-oxide-wrapped BiOI-AgI heterostructured nanocomposite as a high-performance photocatalyst for dye degradation under solar light irradiation (original) (raw)
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Applied Sciences
This study presents a novel method for the development of TiO2/reduced graphene oxide (rGO) nanocomposites for photocatalytic degradation of dyes in an aqueous solution. The synergistic integration of rGO and TiO2, through the formation of Ti–O–C bonds, offers an interesting opportunity to design photocatalyst nanocomposite materials with the maximum absorption shift to the visible region of the spectra, where photodegradation can be activated not only with UV but also with the visible part of natural solar irradiation. TiO2@rGO nanocomposites with different content of rGO have been self-assembled by the hydrothermal method followed by calcination treatment. The morphological and structural analysis of the synthesized photocatalysts was performed by FTIR, XRD, XPS, UV-Vis DRS, SEM/EDX, and Raman spectroscopy. The effectiveness of the synthesized nanocomposites as photocatalysts was examined through the photodegradation of methylene blue (MB) and rhodamine B (RhB) dye under artificia...
Egyptian Journal of Aquatic Research, 2018
The synthesizing of TiO 2 @rGO nanocomposites using an efficient method has been carried out to enhance the photodegradation activities of TiO 2. Reduced graphene oxide (rGO) synthesis has been illustrated as a key step. The preparation of TiO 2 @rGO is highly needed and recommended to develop an effective way for the reduction of GO. Our study illustrated an environmentally simple method for TiO 2 @rGO preparation and demonstrated its efficiency for photocatalytic process by utilizing rhodamine-B dye as an organic pollutant. Synthesized nanoparticles of reduced TiO 2 @rGO have an observable increase in photo-energy adsorption leading to the increase of the photodegradation reactions. From the obtained results, TiO 2 @rGO nanocomposites showed great ability to absorb photo-energy and enhance the pho-todegradation reactions. Moreover, the results revealed that the 3% TiO 2 @rGO have the best performance than 1% TiO 2 @rGO at pH = 9.0, 30 mg/l initial dye concentration and 60 min irradiation duration. The reduced graphene oxide production was considered as an influential co-catalyst for improving the TiO 2 photocatalytic activities mainly owing to; the fast separation of h + /e À and the adsorption improvement. Our study affirms the production of promising applicable particles using the environmental photocatal-ysis process in particular with regard to wastewater purification.
Sustainable Environment Research, 2021
The present study discusses the synthesis of Nb doped TiO 2 /reduced graphene oxide (rGO) intercalated nanocomposites via sol-gel route at a lower temperature by using different loading amounts of graphene oxide (GO) (1 to 10 wt%). The synthesized composite materials were further characterized by copious instruments such as X-ray Diffractometer, UV-Vis Diffuse Reflectance Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscopy, Brunauer-Emmett-Teller surface area analysis, Raman and Fourier Transform-Infrared Spectroscopy. The experimental results stated that the Nb doped TiO 2 nanoparticles uniformly distributed on the surface of rGO with an interfacial linking bond between TiO 2 and rGO. Later, the photocatalytic degradation of Rhodamine B (RhB) dye using produced materials under visible light irradiation was examined. These results revealed that Nb doped TiO 2 / rGO nanocomposites exhibited better photocatalytic performance than Nb doped TiO 2 for the removal of RhB dye. However, among all, the nanocomposite having 5 wt% of GO content achieves the highest degradation efficiency for RhB dye approximately 98% under visible light exposure. Altogether, the unique properties such as electron accepting and transporting properties of GO in the nanocomposite is caused to enhance photocatalytic activity by minimizing the charge carrier's recombination rate.
Catalysts
In this study, a green and facile thermal reduction of graphene oxide using an eco-friendly system of d-(+)-glucose and NH4OH for the preparation of reduced graphene oxide was described. The obtained reduced graphene oxide dispersion was characterized by SEM, Dynamic Light Scattering, Raman and X-Ray Photoelectron Spectroscopy. TiO2 nanoparticles and reduced graphene oxide nanocomposites were successively prepared and used in the preparation of heterogeneous photocatalysts that were characterized by Atomic Force Microscopy and Photoluminescence Spectroscopy and subsequently tested as visible light photocatalysts for the photodegradation of Alizarin Red S in water as target pollutant. Obtained results of photocatalytic tests regarding the visible light photocatalytic degradation of Alizarin Red S demonstrated that the use of reduced graphene oxide in combination with TiO2 led to a significant improvement for both adsorption of Alizarin Red S on the catalyst surface and photodegradati...
Applied Catalysis B: Environmental, 2012
Reduced graphene oxide-TiO 2 composites (GOT) were prepared by liquid phase deposition followed by post-thermal reduction at different temperatures. The composite materials were systematically evaluated as photocatalysts for the degradation of an important pharmaceutical water pollutant, diphenhydramine (DP), and an azo-dye, methyl orange (MO), under both near-UV/Vis and visible light irradiation as a function of the graphene oxide (GO) content. A marked compositional dependence of the photocatalytic activity was evidenced for DP and MO pollutants degradation and mineralization under both UV/Vis and visible light. Especially under visible light, optimum photocatalytic performance was obtained for the composites treated at 200 • C comprising 3.3-4.0 wt.% GO, exceeding that of the benchmark P25 (Evonik) catalyst. According to scanning electron microscopy, Raman spectroscopy, and porosimetry analysis data, this was attributed to the optimal assembly and interfacial coupling between the reduced GO sheets and TiO 2 nanoparticles. Almost total degradation and significant mineralization of DP and MO pollutants (in less than 60 min) was achieved under near-UV/Vis irradiation for the optimum GOT composites. However, higher GO content and calcination temperatures (350 • C) led to detrimental effects due to the GO excess and the disruption of the GO-TiO 2 binding. Photocatalytic experiments employing sacrificial hole and radical scavenging agents revealed that photogenerated holes are the primary active species in DP degradation for both bare TiO 2 and GOT under UV/Vis irradiation, while an enhanced contribution of radical mediated DP oxidation was evidenced under visible light. These results combined with the distinct quenching of the GO photoluminescence under visible and NIR laser excitation, indicate that reduced GO acts either as electron acceptor or electron donor (sensitizer) of TiO 2 under UV and visible light, respectively. Fine-tuning of the reduced GO-TiO 2 interface is concluded as a very promising route to alleviate electron-hole recombination and circumvent the inherently poor light harvesting ability of TiO 2 in the visible range.
Highly photodegradation of organic dye pollutant RhB using TiO2-modified reduced graphene oxide
2021
TiO2-modified reduced graphene oxide (TiO2-rGO) has been studied in one-process step synthesis via the hydrothermal method. In this study, the various concentrations of rGO were investigated and characterized by fourier transform infrared (FTIR), x-ray diffraction (XRD), scanning electron microscope (SEM), surface area analyzer (SAA), thermogravimetric analysis/differential thermal analysis (TGA/DTA), and spectroscopy UV-Vis. In addition, the photodegradation of rhodamine-B was studied by a batch system under visible light irradiation at wavelength 554 nm. The optimum experimental results showed that the presence of rGO in TiO2 nanostructures could improve the specific surface area until 248.58 m2 g− 1 and enhanced the photodegradation efficiency until 70.66% under visible light irradiation. The photocatalyst stability was evaluated for five cycles experiment and the performance have reduced 6.58% efficiency.
ACS Omega
Organic pollutants, such as synthetic dyes, are treated to prevent them from contaminating natural water sources. One of the treatment methods is advanced oxidation process using a photocatalyst material as the active agent. However, many photocatalysts are hindered by their production cost and efficiency. In this study, nanocomposites consisting of reduced graphene oxide and titanium dioxide (rGO/TiO 2) were prepared by a simple and green approach using the microwaveassisted method, and we utilized a graphene oxide (GO) precursor that was fabricated through the Tour method. The ratios of rGO/TiO 2 in nanocomposites were varied (2:1, 1:1, and 1:2) to know the influence of rGO on the photocatalytic performance of the nanocomposites for rhodamine 6G degradation. Transmission electron microscopy (TEM) observation revealed that a transparent particle with a sheetlike morphology was detected in the rGO sample, suggesting that a very thin film of a few layers of GO or rGO was successfully formed. Based on scanning electron microscopy (SEM) observation, the rGO/TiO 2 nanocomposites had a wrinkled and layered rGO structure decorated by TiO 2 nanoparticles with average diameters of 125.9 ± 40.6 nm, implying that rGO layers are able to prevent TiO 2 from agglomeration. The synthesized product contained only rGO and TiO 2 in the anatase form without impurities that were proven by Raman spectra and X-ray diffraction (XRD). The nanocomposite with rGO/TiO 2 ratio 1:2 (composite C) was found to be the best composition in this study, and it was able to degrade 82.9 ± 2.4% of the rhodamine 6G after UV irradiation for 4 h. Based on a time-resolved photoluminescence study at wavelength emission 500 nm, the average decay lifetime of R6G-rGO/ TiO 2 composites (2.91 ns) was found to be longer than that of the R6G-TiO 2 sample (2.05 ns), implying that the presence of rGO in rGO/TiO 2 composites successfully suppressed the electron−hole recombination process in TiO 2 and significantly improved their photocatalytic performance. This study showed that the rGO/TiO 2 nanocomposites synthesized through relatively simple and ecofriendly processes display promising prospects for photocatalytic degradation of dyes and other recalcitrant pollutants in a water stream.
ACS Omega, 2021
Semiconductor nanoparticles are promising materials for light-driven processes such as solar-f uel generation, photocatalytic pollutant remediation, and solar-to-electricity conversion. Effective application of these materials alongside light can assist in reducing the dependence on fossil-fuel driven processes and aid in resolving critical environmental issues. However, severe recombination of the photogenerated charge-carriers is a persistent bottleneck in several semiconductors, particularly those that contain multiple cations. This issue typically manifests in the form of reduced lifetime of the photoexcited electrons-holes leading to a decrease in the quantum efficiency of various light-driven applications. On the other hand, semiconducting oxides or sulfides, coupled with reduced graphene oxide (RGO), have drawn a considerable interest recently, partly because of the RGO enhancing charge separation and transportation through its honeycomb sp 2 network structure. High electron mobility, conductivity, surface area, and cost-effectiveness are the hallmark of the RGO. This Mini-Review focuses on (1) examining the approach to the integration of RGO with semiconductors to produce binary nanocomposites; (2) insights into the microstructure interface, which plays a critical role in leveraging charge transport; (3) key examples of RGO composites with oxide and sulfide semiconductors with photocatalysis as application; and (4) strategies that have to be pursued to fully leverage the benefit of RGO in RGO/ semiconductors to attain high photocatalytic activity for a sustainable future. This Mini-Review focuses on areas requiring additional exploration to fully understand the interfacial science of RGO and semiconductor, for clarity regarding the interfacial stability between RGO and the semiconductor, electronic coupling at the heterojunction, and morphological properties of the nanocomposites. We believe that this Mini-Review will assist with streamlining new directions toward the fabrication of RGO/ semiconductor nanocomposites with higher photocatalytic activity for solar-driven multifunctional applications.
Graphene-based nanostructures for enhanced photocatalytic degradation of industrial dyes
Emergent Materials, 2020
Graphene oxide (GO) is an sp 2-bonded single atomic layer of carbon atoms with plenty of oxy-functional groups at its surface. The occurrence of large surface area (~2630 m 2 /g), surface functionalities, electronic, and mechanical properties make graphene-based compounds favorable for remediation applications. We report the synthesis and comparative dye degradation efficiencies of two titania (TiO 2)-based composites, GO-TiO 2, and reduced GO-TiO 2 (rGO-TiO 2). Both the composites are characterized using SEM-EDX, TEM, FTIR, and XRD. We study the photocatalysis-mediated degradation of anionic dye Eosin Yand cationic dye Methylene blue (MB) in aqueous dispersions under white light and UV irradiation. Our results demonstrate that rGO(10 wt%)-TiO 2 composite shows the maximum degradation (~95%) of both 10 ppm Eosin Y and MB dyes in the aqueous dispersion. The enhanced photocatalytic activity of rGO-TiO 2 composites as compared to TiO 2 and GO-TiO 2 can be credited to the presence of efficient electron shuttling from the conduction band of TiO 2 into the conductive regions of graphene which eventually restricts further recombination of e − /h + pairs. Furthermore, the effects of solution pH and TiO 2 loading are studied on the degradation process.