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Herein, we prepared hexagonal MoO3 (h-MoO3) nanorods by homogenous co-precipitation and utilized them to fabricate a composite h-MoO3-exfoliated graphite (EG) electrode. The above composite was characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and UV-Vis spectroscopy, and used for the degradation of cationic (met...
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High quality and mono-dispersed ZnO nanowire and nanorod were firstly synthesized using co-precipitation method without using any organic solvents in the whole preparation process, which is consistent with the development of green chemistry and also can be used for large-scale production. The co-precipitation method is so popular with us that it is...
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Citations
... Then, the simulated naphthalene-contaminated wastewater was exposed to visible light for 60 min. At 5,10,15,20,30,45, and 60 min, an aliquot of approximately 5 mL of the reaction solution was removed. To ensure that the collected reaction solution did not contain the catalyst, the sample aliquot was passed through a syringe filter (0.45 μm). ...
Polycyclic aromatic hydrocarbons are a class of persistent organic water pollutants that raise serious concerns owing to their carcinogenicity and other negative impacts on humans and ecosystems. In this study, Bi2MoO6/reduced graphene oxide (rGO) nanocomposites were designed and prepared for the adsorption-assisted photodegradation of naphthalene molecules in an aqueous medium. The synthesized Bi2MoO6 nanoplates and Bi2MoO6/rGO nanocomposites were characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, high-resolution transmission microscopy, X-ray photoelectron spectroscopy, ultraviolet spectroscopy, Brunauer–Emmett–Teller, and photoluminescence measurements. The photodegradation of naphthalene molecules was observed to assess the photocatalytic characteristics of the samples under visible light. The Bi2MoO6/rGO nanocomposites exhibited significantly improved photocatalytic efficiency compared to pure Bi2MoO6. Among the nanocomposites, those containing 2 wt % rGO showed the best photocatalytic activity. The incorporation of rGO enhanced the visible light absorption and decreased the recombination rate of photogenerated charge carriers. Moreover, a Bi2MoO6/rGO nanocomposite showed excellent reusability for five cycles.
... The co-precipitation method simultaneous nucleation, growth, agglomeration processes that occur on the surface of the substrate (Rane et al., 2018). Although many researchers across the globe reported the co-precipitative synthesis of MoO3 for various applications like industrial wastewater treatment, photodegradation of dyes (Ama et al., 2018;Tariq et al., 2020) etc., no single report available for supercapacitor application. Tian et al. (Tian et al., 2017) have synthesized needle like CoMoO4 via chemical co-precipitation in hydrothermal condition, and observed that the presence of Mo in CoMoO4 ...
An emerging novel energy storage device-supercapacitors can store electrical energy and deliver quickly whenever needed. Supercapacitors hold potential to replaces batteries and conventional capacitors, due to its relatively higher energy density, power density, fast charge discharge rate, cycling stability. The performance of supercapacitor mainly depends on the nature of electrode material, so researchers focused on the developing electrode material. In this perspective, metal oxides with more active site are considered as competent candidate for enhanced supercapacitive performance. In this review concise description of synthesis of MoO3 targeted via numerous strategies such as hydrothermal, chemical bath deposition, spray pyrolysis and co-precipitation has been discussed. This discussion highlights the future opportunities of MoO3 electrode material for the supercapacitor application.
... Despite this, the as-produced product after reduction does not appear identical to pristine graphene because of the existence of crystal defects and some residual oxygen functionalities [198] consequently, this product is more accurately called rGO. Regardless of surface defects, both GO and rGO have been extensively applied in various applications, such as supercapacitors [199] batteries [200,201] water treatment [22] membrane separation [202,203] catalysis [204][205][206] biomedical fields [207] and smart textiles [208]. This section highlights various reduction processes, such as thermal [209] microwave irradiation [210] photoreduction [211] hydrothermal [212] electrochemical [213] chemical [57,214] and green Table 1 Summary of conventional and recent approaches for the chemical oxidation of graphite for the synthesis of GO. reduction [215] methods for the preparation of rGO. ...
Graphene research has become an emerging frontier in materials science because of its potential as a versatile material in multiple applications, from electronics, sensors, water treatment, batteries, displays, advanced composites, and coatings to biomedical applications. While the community has witnessed tremendous advances in the laboratory-scale synthesis of graphene, it is crucial to focus on sustainable large-scale graphene production to adopt graphene-based technology at an industrial scale. Several top-down and bottom-up methods have been developed to realize affordable graphene production. However, a low-cost scalable graphene production method with acceptable quality remains a challenge; top-down processes are demonstrating their potential to offer a more straightforward solution. Herein, we present an overview of recent progress in the research and development of top-down graphene synthesis methods and their potential to scale-up graphene production. We cover the effect of different synthesis parameters on the quality control of graphene. In addition, we provide a brief overview of bottom-up methods. Finally, we discuss the existing challenges and future directions in top-down methods for large-scale graphene production.
... Electrochemical advanced oxidation processes (EAOPs) have become one of the most important technologies for environmental remediation [6,7]; they can be used to oxidize nearly all types of organic compounds into harmless products via highly reactive hydroxyl radical (OH • ) having a redox potential of 2.8 V [8][9][10][11][12][13] The advantage of EAOPs is that they are "environment-friendly" as they do not transfer pollutants from a phase to another (as in adsorption) and they do not produce large amounts of hazardous sludge [14][15][16][17]. In EAOPs, the organic pollutants are destroyed by hydroxyl radical OH • which is generated through the electron donors, namely the adsorbed water/OH − groups, or by the superoxide radical ion (O 2 •− ) being generated by the oxygen as an Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12678-020-00625-8) ...
Barium hydrogen phosphate (BaHPO4) thin films were electrodeposited on fluorine-doped tin oxide (FTO) and used as electrocatalysts for organics degradation. The effects of applied current density and deposition time on the phase and morphology of electrodeposited films were analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) spectroscopy, Raman spectroscopy, electrochemical impedance spectroscopy (Mott–Schottky) plots, and photocurrent response. The electrodeposited BaHPO4 films crystallize in the orthorhombic structure and form platelets on the FTO substrate. Response surface methodology (RSM) was used to optimize the operational conditions. Four independent process variables were considered: NaCl concentration, rhodamine B (RhB) initial concentration, applied current density, and reaction time. Based on the model prediction, the optimum conditions for RhB degradation were determined with the maximum RhB degradation of 98.78%. The corresponding experimental value of RhB degradation under the optimum conditions was determined as 99%, which is very close to the optimized one, implying that RSM is a powerful strategy for the process optimization. The photoelectrochemical degradation of RhB, performed at optimal operational conditions, allowed the very fast degradation rates of almost 99% during 7 min due to the synergic effect while combining photocatalysis and electrocatalysis.
Graphical abstract
... The generated positive holes participate in the oxidation of contaminants. Several semiconductor and nanohybrid materials, such as TiO 2 , ZnO, SnO 2 , CuO, SrTiO 3 , Bi 2 WO 6 , WO 3 , CdS, MoS 2 , Ag/Ag 2 Te, g-C 3 N 4 , etc., have been studied as photocatalyst in wastewater treatment through photocatalysis [23][24][25][26][27][28][29][30][31][32][33][34][35]. Among them, titania (TiO 2 ) and zinc oxide (ZnO) are the more explored and applied photocatalysts due to their abundance, non-toxic behavior, economic feasibility, chemical and thermal stability, environmentally friendly nature and most importantly optical and electrical characteristics [17,36]. ...
Photocatalysis is considered as a promising, sustainable, economically feasible, environmentally friendly technique to improve the quality of the wastewater with zero secondary waste and help to fight the clean water scarcity. Advances in the development of semiconductor nanomaterials have attracted a considerable amount of interest in wastewater treatment. Several UV/visible light excitable nanomaterials such as TiO 2 , ZnO, MoS 2 , g-C 3 N 4 , CuO, Fe 2 O 3 , CdS, SnO 2 , ZnS, SrTiO 3 , etc., and their nanohybrids have been studied as photocatalysts to degrade organic/inorganic pollutants from wastewater. Their efficiency can be controlled by optimizing various parameters (e.g., pH, temperature, the dosage of catalyst, oxidants, light intensity, morphology, etc.) during the reaction. The experimental conditions significantly affect the performance of photocatalyst in the photo-degradation of contaminants. Optimization of operating parameters and their effect on photocatalytic degradation of water pollutants will be the main focus of this chapter. It was noticed that photocatalytic property of materials can be improved by changing morphologies, doping of element, addition of oxidant, high surface area, and high light intensity. Also, the brief about designing strategies and
... In the case of h-MoO 3 , the peak at 252 cm -1 is attributed to the swing of terminal oxygen atom, and the stretching of Mo-O-Mo bonds corresponds to the peak at 690 cm -1 . In addition, the peaks at 899 cm -1 and 976 cm -1 are ascribed to the stretching of terminal oxygen atom [29]. Thus, the Raman spectrum results indicate that the prepared MoO 3 is quite pure. ...
This report aims to systematically study the photocatalytic properties of α-MoO3 and h-MoO3. Here, α-MoO3 nanorods and h-MoO3 hexagonal prism were successfully synthesized via a facile hydrothermal method. The products were characterized in detail, and the results showed that the products are very pure with excellent morphology. The photocatalytic properties of MoO3 were evaluated via methylene blue and rhodamine B dyes as well as tetracycline. The results indicate that the photocatalytic efficiency of α-MoO3 is better than that of h-MoO3, and α-MoO3 has the best photocatalytic activities at 24 h because of the synergistic adsorption and photocatalysis and dye-sensitized mechanism. We further proposed a charge separation model between (002) and (00_2) polar surfaces via density functional theory computation to explain the enhanced photocatalytic activities. The excellent photocatalytic efficiency of α-MoO3 suggests that it can be used for photodegradation of wastewater.
... Numerous studies were aimed at obtaining the orthorhombic structure of molybdenum(VI) oxide with various morphologies (nanorods [19], nanobelts [20,21], nanotubes [22], nanoplates [23], nanosheets [24], nanofibers [25], hollow microspheres [26], etc.) using a diversity of synthetic methods and approaches, in particular, by spray pyrolysis [27,28], physical vapor deposition [29], magnetron sputtering [30], and hydrothermal synthesis [21]. Production of onedimensional structures of hexagonal h-MoO 3 requires a more careful choice of synthesis method and conditions because of lower thermodynamic stability, and there are rather few reports of successful synthesis of this material [31][32][33][34]. The researchers often failed to reach necessary heterogeneity and hierarchical organization of the obtained structures, which had a significant impact on the functional properties of the product [7,16,35]. ...
... Several techniques, such as adsorption, photocatalysis, photoelectrocatalysis, reverse osmosis, membrane separation, flocculation, biological precipitation, electrochemical approaches, ionexchange, and desalination, have been used in water remediation [17,[31][32][33][34][35][36][37][38][39][40][41][42]. Fig. 1 depicts a variety of sources of water pollution and current water purification techniques. ...
Deterioration of water quality and the unavailability of drinkable water are pressing challenges worldwide. Removal of toxic organic and inorganic pollutants from water is indispensable for a clean environment, as a response to water scarcity, and for human society. Adsorption-based water technologies are among the most favoured and widely used because of their high efficiency at low-cost, without relying on complicated infrastructure. In recent years, carbon nanomaterials (CNMs), such as graphene and derivatives, carbon nanotubes, carbon nanofibers, nanoporous carbon, fullerenes, graphitic carbon nitride, and nanodiamonds have been extensively exploited as adsorbents due to their extraordinary surface properties, easy modification, large specific surface area, controlled structural varieties, high chemical stability, porosity, low density, ease of regeneration, and reusability. Graphene oxides and other oxidised carbons provide strong acidity and abundant functional groups, and demonstrate excellent adsorption of cationic and basic compounds via electrostatic and hydrogen bonding interactions, while their pristine counterparts exhibit hydrophobic surfaces and offer high adsorption via strong p-p interactions. This review provides a thorough overview of state of the art in CNMs, including significant past and recent advances, as well as future strategies for the use of carbon-based nanoadsorbents in water treatment. This review primarily emphasises the fundamentals of adsorption, its mechanistic aspects, synthesis and properties of CNMs, and adsorption performances of CNMs and their nanocomposites with inorganic and organics materials. Structural engineering and activation processes produce materials with enhanced adsorptive properties and separation efficiencies. Furthermore, the formation of CNMs with 2D and 3D macro-/micro-structures with high porosities is a potential approach to improve adsorption performances and extend CNMs use at the industrial level. This review also addresses some vital issues that persist about these adsorbents, which could shape the future research and industrial application of carbon-based nanoadsorbents in water security.
... The best-performing P-BN-2 nanocomposite, containing 2 wt% of 2D h-BN nanosheets, exhibited 93% and 95% degradation of MB and MO, respectively, in 90 min. Ama, Kumar, Adams, and Ray (2018) investigated the photoelectrochemical degradation of cationic (methylene blue, MB) and anionic (methyl red, MR) dyes on a η-MoO 3 -exfoliated graphite (EG) electrode. Well-dispersed MoO 3 in the EG electrode enhanced photon absorption and had higher dye degradation than the bare EG electrode. ...
This is a review of the literature published in 2018 on topics related to hazardous waste management in water, soils, sediments, and air. The review covers treatment technologies applying physical, chemical, and biological principles for contaminated water, soils, sediments, and air.
Practitioner points
• The management of waters, wastewaters, and soils contaminated by various hazardous chemicals including inorganic (e.g., oxyanions, salts, and heavy metals), organic (e.g., halogenated, pharmaceuticals and personal care products, pesticides, and persistent organic chemicals) was reviewed according to the technology applied, namely, physical, chemical and biological methods.
• Physical methods for the management of hazardous wastes including adsorption, coagulation (conventional and electrochemical), sand filtration, electrosorption (or CDI), electrodialysis, electrokinetics, membrane (RO, NF, MF), photocatalysis, photoelectrochemical oxidation, sonochemical, non‐thermal plasma, supercritical fluid, electrochemical oxidation, and electrochemical reduction processes were reviewed.
• Chemical methods including ozone‐based, hydrogen peroxide‐based, persulfate‐based, Fenton and Fenton‐like, and potassium permanganate processes for the management of hazardous were reviewed.
• Biological methods such as aerobic, anaerobic, bioreactor, constructed wetlands, soil bioremediation and biofilter processes for the management of hazardous wastes, in mode of consortium and pure culture were reviewed.
... Recently, an extensive number of semiconductor nanomaterials (viz. SnO 2 , TiO 2 , h-MoO 3 , ZnO, and their composites) have been considered as vital photocatalysts for the removal of harmful contaminants [9,[23][24][25]. After TiO 2 , ZnO is the most explored metal oxide semiconductor because of its good catalytic, electronic, photochemical properties, and high quantum efficiency beside its cost-effective and non-toxic nature [24]. ...
In this study, ZnO/g-C 3 N 4 heterostructure was synthesized with enhanced photodegradation potential for polycyclic aromatic hydrocarbons (PAHs) (viz. naphthalene) in water using visible light. The as-prepared catalysts were characterized via different techniques such as scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infra-red, ultraviolet visible (UV-Vis), photoluminescence, and X-ray diffractometry to elucidate their physicochemical and structural properties. The identified properties of the newly synthesized heterostructure catalyst indicated a successful integration of physicochemical characteristics suitable for effective photocatalytic degradation activities. The kinetics study and mechanism of photodegradation of naphthalene using ZnO/g-C 3 N 4 heterostructure have been discussed in detail. The photodegradation outcomes demonstrated that the synthesized heterostructure of semiconductors was more effective than the parent catalyst ZnO nanoparticles because of better light absorption for higher photogeneration of electrons and holes, suppressed recombination rate, and consequently prolonged availability of active species for degradation. The ZnO/g-C 3 N 4 heterostructure has exhibited a photocatalytic efficiency of 84.5% in 4 h, which was relatively higher than the photocatalytic efficiency of individual photocatalysts. Thus, this report highlights the potential of as-prepared heterostructure for the photodegradation of naphthalene under visible light, therefore suggesting an avenue for the treatment of wastewater contaminated with PAHs.
