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•ZnO, WO3, binary composite WO3-ZnO and ternary WO3-ZnO@rGO nanocomposites were prepared.•The minimum bandgap was 2.62 eV for WO3.•Maximum photocatalytic activity (i.e. > 90 %) was ...observed by rGO based composite.
Novel graphene supported ternary nanocomposites (WO3-ZnO@rGO) were prepared via simple ultrasound assisted fabrication of WO3-ZnO binary nanostructures over 2D rGO nanosheets. Structural, morphological and elemental characterization of as-synthesized samples were carried out through X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM) and Energy dispersive X-ray spectroscopy (EDX). Optical band gap analysis under UV–vis spectroscopy (UV–vis) revealed a decrement in the band gap energy value of WO3-ZnO@rGO ternary nanocomposites. Current-voltage (I–V) measurements evidenced the ohmic response of rGO supported WO3-ZnO nanocomposites as compared to bare samples. To evaluate the photocatalytic efficiency of WO3-ZnO@rGO nanocomposites in comparison to bare nanostructures, wastewater organic pollutant methylene blue (MB) dye was chosen as benchmark reaction. Results suggested that impregnation of WO3-ZnO over rGO sheets significantly improved the photocatalytic efficiency of WO3-ZnO@rGO with 94 % dye removal within 90 min under visible light irradiation. The enhanced photocatalytic efficiency is ascribed to synergistic effects originating at WO3-ZnO@rGO interfaces subsidizing high quantum yield and effective separation and transfer of photo induced electron-hole pairs. Moreover, WO3-ZnO@rGO also retained its remarkable dye degradation efficiency even after four recycling tests.
Tungsten oxide (WO3), Iron and vanadium co-doped tungsten oxide (FeVWO3), and the composite of iron and vanadium co-doped tungsten oxide with graphitic carbon nitride (FeVWO3@g-C3N4) were prepared ...for the photocatalytic study. WO3 and FeVWO3 were synthesized by co-precipitation, and the composite FeVWO3@g-C3N4 was synthesized by an ultra-sonication approach. All the prepared materials were analyzed by different techniques. Structural study was done by XRD, functional group analysis by FTIR, and SEM was used for the morphological study of the nanoparticles. EIS measurements were done to investigate the electrical properties of fabricated materials. Photocatalysis was performed for the band gap analysis. Pendimethalin (PM) a herbicide and aspirin (pharmaceutical product) were used in photocatalysis and degraded by the prepared photocatalysts (WO3, FeVWO3, and FeVWO3@g-C3N4). WO3 and FeVWO3 have 2.62 eV and 2.34 eV Eg values of band gap, respectively. FeVWO3 has a lower Eg value than WO3. The decrease is due to the doping, and generation of further energy levels in the band gap of the pure sample, and these energy levels cause changes in the electronic structure of the sample. The composite shows a high degradation efficiency. The percentage degradation of pendimethalin and aspirin by FeVWO3@g-C3N4 was 82.26 % and 92.84 %. It is because of the presence of g-C3N4 which provides greater surface area for better degradation efficiency.
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•The Hydrothermal method was used for the preparation of cobalt ferrites and its composites.•CoFe2O4/CoFe LDH@CNTs showed improvement in electrochemical properties.•CoFe2O4/CoFe ...LDH@CNTs was applied as electrode material for alkaline water splitting.
Designing highly efficient and durable multicomponent heterostructured composites as catalytic materials for concomitant hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is highly desirable. Researchers all over the world are continuously working to develop such materials. Herein, CNTs wrapped CoFe2O4/CoFe LDH (CoF/CoFe LDH@CNTs) ternary composite is synthesized by hydrothermal and ultra-sonication routes. Numerous methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrical Mott-Schottky, and electrochemical impedance spectroscopy (EIS) are employed to study structure, morphology, flat band potential, and electrochemical properties of prepared samples. In terms of water splitting performance, CoF/CoFe LDH@CNTs composite showed predominant performance for both HER and OER activities, as compared to its analogs (CoF and CoF/CoFe LDH). Faster electron transfer is also exhibited by CoF/CoFe LDH@CNTs, as it possesses a lower Tafel slope. For OER, CoF/CoFe, LDH@CNTs require a small overpotential of 170 mV to reach a current density of 10 mA cm−2 in 1 M KOH, with a Tafel slope of 42 mV dec-1. Similarly, for HER an overpotential of 218 mV is required to drive 10 mA cm−2 with a small Tafel slope of 31 mV dec-1. Impedance studies show a small value of charge transfer resistance (Rct = 1.11 Ω) for CoF/CoFe, LDH@CNTs. Significant electrochemical performance for CoF/CoFe, LDH@CNTs for both half-reactions (OER and HER) is ascribed to the synergy among electrochemically active CoF and CoFe LDH, and a highly conductive network of CNTs. The present strategy improves the electrochemical performance of electrochemical systems relevant to energy applications.
In this work, multifunctional Ti3C2 MXene@Graphene composite aerogel fabricated with bimetallic NiCo2Se4 (denoted as NCSe@MGA) have been prepared by hydrothermal method with the assistance of ...wet-chemical approach. 3D spatial arrangement of NCSe microspheres in hierarchical aerogel structure improved the exposed electroactive surface area. High surface to volume ratio and luxuriant 3D porous framework of aerogel enabled fast multi-dimensional ion-phase transport. Ti3C2 MXene@Graphene composite aerogel act as flexible skeleton to facilitate strain release and restrained the pulverization of NCSe during electrochemical tests. As a result, NCSe@MGA exhibited high specific capacity of 352.4 mAh g − 1 at 1 A g − 1 with 99.6% initial coulombic efficiency, and maintained capacity retention rate to 91.5% after 5000 consecutive cycles at 12 A g − 1. In case of electrocatalytic water splitting, NCSe@MGA realized 10 mA cm−2 current at significantly low overpotentials of 78 and 201 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. The value of Tafel slope was as low as 55 mV dec−1 (HER) and 79 mV dec−1 (OER), demonstrating fast kinetics. For both half reactions, no significant decay of current density was observed during 10 h electrolysis test. The synergistic effects stemming from intimate contact among NCSe, MXene and Graphene ultimately boosted the electrochemical activity of NCSe@MGA in comparison to NCSe and NCSe@GA. This study proposes a feasible strategy to design 3D electrode materials with optimal properties for multi-range technological applications.
A facile hydrothermal and ultrasonication method used to synthesize the MoO3 nanowires (NWs) intercalated MXene composite. MoO3/MXene nanocomposite was fabricated on carbon cloth (CC) to prepare the ...MoO3/MXene@CC electrode. Intercalation of MoO3 NWs in MXene layers prevented the collapse of Al etched MXene sheets and enhanced the conductive channels in ultimate nanostructures. When applied for electrochemical measurements, MoO3/MXene@CC significantly improved specific capacity. For pristine MoO3@CC, the specific capacitance was calculated as 466.7 F/g (at 5 mV/s) and 442 F/g (at 1 A/g) from cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) data, respectively. Meanwhile, MoO3/MXene@CC showed a high specific capacitance of 783.4 F/g at 5 mV/s and 775 F/g at 1 A/g under the CV and GCD measurements. Electrochemical impedance spectroscopy (EIS) data evaluated the resistivity performance of MoO3/MXene@CC. The calculated equivalent series resistance (RES) and charge transfer resistance (RCT) values for MoO3/MXene@CC were 5.4 Ω and 31.3 Ω, respectively. Moreover, MoO3/MXene@CC showed excellent cyclic stability with 96.4% retention of its initial specific capacitance even after 6000 cycles. Results suggest that the prepared MoO3/MXene@CC hybrid can be used as an efficient electrode material for electrochemical energy storage applications.
Currently, graphene and its functional derivatives are in high demand due to their unprecedented potential to build multifunctional catalysts. Here, we report the synthesis of highly active and cheap ...photo-catalyst materials consisting of sol-gel synthesized ZnO nanochips, assembled over the oxidized (GO) and partially reduced (RGO) derivatives of graphene in presence of ultrasound radiations. Structure, crystallite size, morphology, optical and photo-catalytic properties of as synthesized ZnO nanochips, ZnO@GO, and ZnO@RGO nanocomposites were investigated. Results demonstrated that ZnO nanochips incorporated over graphene sheets showed higher photo-catalytic rates with ∼76.5-98.9% degradation of Rhodamine-B (RhB) and Methylene Blue (MB) within 90 min of visible light irradiation. Moreover, ZnO@RGO was more efficient photo-catalyst than ZnO@GO with ∼2.4 and ∼2 times higher kinetic rates for the removal of RhB and MB, respectively. The superior performance of ZnO@RGO was ascribed to partially restored conjugated structure of RGO that dispense higher charge density on surface of photo-catalyst per unit time, by more effective charge migration and separation across semiconductor-caron (S-C) heterojunctions. The active species involved in degradation process were systematically investigated and a photo-catalytic mechanism was proposed. In addition, ZnO@GO and ZnO@RGO showed good recyclability and resistance to photo-corrosion even after 360 minutes of consecutive photo-catalytic activity.
In the current report, pure V2O5, a series of Gd doped V2O5 (1 wt%, 3 wt%, 5 wt% and 10 wt%) and graphene integrated Gd–V2O5 photocatalysts have been prepared using a facile wet chemical approach. ...The effect of Gd+3 ions substitution and RGO support on V2O5 was studied by the different analytical techniques. X-ray diffraction (XRD) results showed the orthorhombic crystal structure of synthesized samples with crystallize size in range of 22–35 nm. Morphological analysis showed nanorods and nanorod arrays like appearance of V2O5, Gd–V2O5 and GdV-2O5/RGO, respectively. Gd–V2O5 and Gd–V2O5/RGO exhibited enhanced optical response in the visible region along with decrease in the band gap values for Gd doped V2O5 samples. BET surface area of Gd–V2O5 and Gd- V2O5/RGO was calculated as 12.39 g/m2 and 15.35 g/m2 that was found to be higher than pristine V2O5. To study the photocatalytic activity of synthesized photocatalysts, methylene blue (MB) was chosen as model pollutant. Among the Gd doped V2O5 samples, highest photocatalytic activity (45.62%) was achieved by optimal concentration of 5 wt% Gd–V2O5 that is accredited to effective separation of electron-hole pairs. While Gd–V2O5/RGO showed 2.1 times higher dye removal (97.12%) than unsupported Gd–V2O5, under the visible light irradiation. The significantly high photocatalytic activity of Gd–V2O5/RGO is due to the synergistic effect aroused by combined action of Gd+3 ions doping and advantageous properties of highly conductive and large surfaced graphene. Recycling experiments for V2O5 derivatives showed good stability and recyclability of photocatalysts. Additionally, Gd–V2O5/RGO was found to be more potential anti-bacterial agent than V2O5 and Gd–V2O5.
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A facile strategy comprising co-precipitation and ultra-sonication methods was used to fabricate WO3/CuO and WO3/CuO/rGO nanocomposites. X-ray Diffraction (XRD) and Fourier transform infrared (FT-IR) ...spectroscopy, Scanning electron microscopy (SEM), optical, and electrochemical measurements were used for the structural, morphological, and electrical analysis of as-synthesized materials. The photocatalytic performance of synthesized materials was explored for the degradation of methylene blue (MB), Rhodamine B (RhB) and benzoic acid. The percentage degradation of MB in presence of CuO, WO3, WO3/CuO, and WO3/CuO/rGO was 56.7%, 75.1%, 86.5%, and 95.5%, respectively, within 90 min of UV-Visible light irradiation. For RhB, the percentage degradation in presence of CuO, WO3, WO3/CuO, and WO3/CuO/rGO was found to be 54.5%, 73.4%, 82.5%, and 93.1%, respectively. For benzoic acid, the percentage degradation was recorded as 35.1%, 77.3%, 84%, and 91.8% for CuO, WO3, WO3/CuO, and WO3/CuO/rGO, respectively. Evidently, during each experiment WO3/CuO/rGO showed highest capability to photodegrade the pollutants due to the generation of heterojunction interface among individual constituents. When applied for antibacterial activity, WO3/CuO/rGO showed 1.7 and 2 mm of zones of inhibition against S. Aureus and K. Pneumonia, respectively. Consequently, it can be anticipated that WO3/CuO/rGO could be used as multifunctional photocatalyst for the treatment of different environmental pollutants.
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•A facile route was adopted for the development of WO3/CuO/rGO nano-heterojunctions.•WO3/CuO/rGO was applied for the photodegradation of RhB, MB and benzoic acid .•Antimicrobial activity of WO3/CuO/rGO was studied against S. Aureus and K. Pneumonia.•Development of nano-heterojunctions improved overall response of WO3/CuO/rGO nanocomposite.
•A novel NiSe2@MXene/rGO aerogel (NSMGA) was fabricated with different mass loading of Ti3C2 MXene.•NSMGA applied as multifunctional electrode material for supercapacitor study and overall water ...splitting.•The optimal electrode (NSMGA-40) exhibited excellent electrochemical performance.•NSMGA-40 showed remarkable stability during electrochemical applications.
In this research, we have designed novel three-dimensional (3D) Ti3C2 MXene/rGO composite aerogels (MGA) integrated with octahedron-like NiSe2 (NS), with different mass loadings of MXene (20 wt% and 40 wt%). Resultant aerogels developed into a cellular lattice like network that significantly improved the contact area among active material and electrolyte. 3D spongy scaffold of MGA boosted the mass diffusion rate, and good electrical conductivity of MXene and rGO provided fast transport of charges during the electrochemical tests, which endowed superior supercapacitor and water splitting performances. Electrode with optimized MXene/rGO ratio i.e., NSMGA-40, exhibited a remarkable specific capacity of 289.7 mAh g−1 at current density of 1 A g−1 and excellent durability of 92.5% over 5000 charge/discharge cycles at 12 A g−1 in a three electrode system for supercapacitor. Meanwhile, as a bifunctional electrocatalyst, NSMGA-40 required a low overpotential of 97 mV and 262 mV to reach 10 mA cm−2 for HER and OER activity, respectively, in alkaline media. The values of Tafel slopes were as small as 89 mV dec−1 (HER) and 75 mV dec−1 (OER), signifying accelerated electron-transfer kinetics. Furthermore, in both cases, NSMGA-40 electrocatalyst withstood a long-term stability test of 10 h. Hence, the obtained results can be manifested for the structural and componential engineering that maximizes the synergetic effects from Ti3C2 MXene, rGO, and NS. Indeed, our fabricated aerogels offer a valuable reference for the fabrication of 3D multicomponent electrode materials for energy storage and conversion applications.
In the current study, NiAl2O4, and silver doped NiAl2O4 were synthesized via a sol-gel approach and their composite with g-C3N4 was successfully prepared via an ultrasonication approach. The ...characterization of as fabricated materials was carried out via various conventional techniques. Furthermore, the electrochemical behavior of the as-fabricated electrode materials was investigated via various electrochemical techniques. The results of electrochemical measurements were analyzed for all three prepared electrodes and Ag-NiAl2O4@g-C3N4 nanocomposite was found to be a more active electrode material than other prepared electrodes. Ag-NiAl2O4 @g-C3N4 showed specific capacitance of 768 Fg−1, 94.01% capacitance retention after 6000 CV cycles, 519 s discharge time, 0.51 Ω charge transfer resistance, 27 WhKg−1, and 187.28 WKg−1 energy and power densities respectively. Ag-NiAl2O4@g-C3N4 can be considered a potential and propitious electrode material for high-performance supercapacitors.
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•Ultrasonication approach was followed to synthesize Ag-NiAl2O4@g-C3N4.•Crystallite size was found< 8 nm.•CV, GCD, and EIS were performed to check the capacitive behavior of as prepared electrodes.•Ag-NiAl2O4 @g-C3N4 showed 768 Fg−1 specific capacitance.•94.27% capacitance retention showed by the fabricated nanocomposite.
