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•Visible active rGO-BiVO4-ZnO catalyst was fabricated by simple hydrothermal method.•TEM image of rGO-BiVO4-ZnO shows the pristine structure of BiVO4 on the rGO sheet.•Degradation ...activity is about 98.4% of CIP in 60 min with excellent reusability.•The ciprofloxacin decomposition pathway is proposed by GC-MS analysis.
A highly effective rGO-BiVO4-ZnO photocatalyst was synthesized by hydrothermal method and characterized by XRD, FE-SEM, HR-TEM, XPS, Photoluminescence, FT-Raman, FT-IR and Diffuse reflectance spectroscopy. The narrow peaks of rGO-BiVO4-ZnO reveal good crystallinity and strong diffraction peaks of GO at 11.30° and 42.43° correspond to the layered structure of GO. Average crystalline size of the rGO-BiVO4-ZnO was 35 nm. TEM images reveal the presence of nanorods of ZnO and pristine structure of BiVO4 on the rGO sheet. The band gap energy for rGO-BiVO4-ZnO is 2.35 eV. The reduced PL emission at 524.6 nm by rGO-BiVO4-ZnO relative to the synthesized ZnO, reveal a decrease of recombination of the photon-induced electron-hole pair by loading of BiVO4 on ZnO. Ternary nanocomposite rGO-BiVO4-ZnO exhibits highest photodecomposition activity, achieving 98.4% decomposition efficiency for ciprofloxacin in 60 min under visible light irradiation. Photogenerated holes play a major role in the photocatalytic decomposition of ciprofloxacin (CIP), Low cost rGO-BiVO4-ZnO is stable and recyclable for effective decomposition of ciprofloxacin. Based on the GC-MS analysis, the CIP decomposition pathway as well as decomposition mechanism of piperazine ring oxidation are proposed. The photodecomposition efficiency is mainly due to charge transfer and excellent electron hole separation by doping of rGO.
Solid polymer electrolytes used in energy storage devices based on Cornstarch and Poly (vinyl Pyrrolidone) blend incorporated with lithium acetate was prepared using the solution casting method. XRD ...results confirmed that the amorphous nature of the as-prepared polymer electrolyte was increased by addition of salt. 80 wt % Cornstarch/20 wt % PVP/60 wt % lithium acetate added polymer blend system attains better amorphous nature than others. At ambient temperature, 60 wt % of lithium acetate added system has better bulk conductivity of 3.52 × 10−5Scm−1 over the frequency range of 42 Hz to 1 MHz using AC impedance spectroscopy studies. The dielectric analysis is confirmed that the higher conducting sample was having high dielectric constant and low relaxation time for enhancing ions dynamic behaviour. The conduction mechanism of the higher conducting polymer electrolyte is explained by small polaron hopping and overlapping large polaron tunnelling conduction mechanism. From the argand plot, it is confirmed that higher conducting sample has low relaxation time.
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•rGO-TiO2 nanocomposite was prepared by simple hydrothermal preparation.•rGO reduces the band gap energy of TiO2 from 3.2 eV to 2.7 eV making rGO-TiO2 visible active.•Ciprofloxacin ...decomposition efficiency of rGO-TiO2 is much higher than TiO2 and TiO2-P25.•Antibacterial activity of rGO-TiO2 nanoparticles reveals that it is more active against S. aureus than E. coli.•rGO-TiO2 can be used as a multifunctional material for photodegradation and antibacterial applications.
The reduced Graphene Oxide based titanium dioxide (rGO-TiO2) nanocomposite was synthesized by a simple hydrothermal preparation and characterized by X-ray Diffraction Analysis (XRD), UV–vis absorption spectroscopy (UV), Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The XRD pattern of rGO-TiO2 indicates the presence of anatase TiO2 and average crystalline size of particles is 32 nm. The optical band gaps of TiO2, GO and rGO-TiO2 nanocomposite are 3.24 eV, 4.3 eV and 2.7 eV respectively. Comparison of efficiencies of three catalysts shows that ciprofloxacin degrades at a faster rate under visible light irradiation in the presence of rGO-TiO2 at 60 min than in presence of pure TiO2 and commercial TiO2-P25. Higher photocatalytic decomposition efficiency of rGO-TiO2 is explained by its reduced electron-hole recombination and visible light activity. The kinetics of photodecomposition reaction was analyzed. Antibacterial activity analysis of rGO-TiO2 nanoparticles reveals that it is more active against S. aureus than E. coli.
Monoclinic scheelite type Bismuth Vanadate (BiVO
4
) nanoparticles (NPs) were prepared by simple hydrothermal method. The prepared BiVO
4
particles were characterized by various analytical studies ...such as Structural, optical, elemental and morphological analysis. The monoclinic scheelite type BiVO
4
was confirmed using X-ray diffraction. Optical band gap was calculated 2.27 eV at the absorbance edge λ = 545 nm using DRS UV spectrum. The elemental composition and functional group were confirmed the BiVO
4
through EDX and FTIR respectively. Rod shaped morphology was observed by electron microscopes like SEM and TEM. The prepared BiVO
4
NP
S
modified electrode was subjected with electrochemical studies like cyclic voltmetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge (GCD) analysis. The rod shaped BiVO
4
NP
S
modified electrode obtained maximum capacitance value of 1166 Fg
−1
.
Reduced graphene oxide-HoVO4-ZnO nanocomposite was prepared via simple hydrothermal method and characterized by X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), ...Energy-Dispersive Spectroscopy (EDX), High-Resolution Transmission Electron Microscopy (HR-TEM), X-Ray Photoelectron Spectroscopy (XPS), FT-Raman, UV–Visible Diffuse Reflectance Spectroscopy (DRS), Electrochemical impedance spectroscopy and Cyclic Voltammogram(CV). The XRD pattern confirmed the formation of hexagonal wurtzite structure of ZnO and monoclinic scheelite structure of HoVO4. FE-SEM images depicted the Wool roving textured reduced Graphene Oxide-HoVO4-ZnO catalyst. As prepared rGO-HoVO4-ZnO exhibits highest photodegradation efficiency achieving at 97.2% and 98% for ibuprofen (IBF)and ciprofloxacin (CIP) respectively in 60 min under UV light illumination. Superoxide radicals (O•-2) play an important role in the decomposition of IBF and CIP. Prepared catalysts were found to be stable and reusable even after six consecutive cycles without loss of catalyst. Also Besides, the electrochemical efficiency and galvanostatic charge-discharge of the rGO-HoVO4-ZnO and HoVO4-ZnO composites electrode materials were evaluated by cyclic voltammetry. rGO-HoVO4-ZnO composite showed higher specific capacitance of 322 Fg-1, compared to HoVO4-ZnO (252 Fg-1) in neutral aqueous electrolyte. The enhancement of specific capacitance of the composite electrode is mainly due to the interconnected conductive network as well as synergism of rGO. The experimental results reveal that rGO-HoVO4-ZnO material is an efficient electrode material for high-performance supercapacitors.
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•Wool roving textured reduced Graphene Oxide-HoVO4-ZnO catalyst was fabricated by a simple hydrothermal method.•Higher efficiency of rGO-HoVO4-ZnO in photodegradation of ibuprofen and ciprofloxacin is due to its synergistic effect.•Higher specific capacitance of 322 Fg-1 makes rGO-HoVO4-ZnO an efficient electrode material for supercapacitors.
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•The needle with spherical shape rGO-HoVO4-TiO2 was prepared by hydrothermal method.•The catalytic performance of rGO-HoVO4-TiO2 is an excellent under visible light.•The reduced ...Graphene Oxide-HoVO4-TiO2 nanocomposite is stable by cyclic test.•Superoxide radicals play a major role in the decomposition ibuprofen.
The photocatalytic decomposition is a highly efficient method for removing environmental pollution. Reduced graphene oxide (rGO) loaded HoVO4-TiO2 was prepared hydrothermally and characterized by XRD, FE-SEM, EDX, TEM, XPS, FT-Raman spectral analysis, FT-IR and UV-DRS. The powder XRD confirmed the formation of the anatase structure of the TiO2 and monoclinic scheelite structure of HoVO4. FE-SEM images of rGO-HoVO4-TiO2 depicted a mixed needle and spherical structure. DRS spectra of rGO and HoVO4 in rGO-HoVO4-TiO2 composite increased its visible absorbance region. The photocatalytic study revealed an enhanced photodecomposition efficiency of rGO-HoVO4-TiO2 composite material than HoVO4, TiO2, rGO-HoVO4, rGO-TiO2 at pH 7 in the removal of ibuprofen. The effects of operational parameters such as the catalyst amount, ibuprofen concentration have been analyzed and compared with the previous reports. The degradation mechanism is proposed for ibuprofen under visible light illumination. Moreover, the rGO-HoVO4-TiO2 catalyst has excellent stability and the photocatalytic decomposition of ibuprofen mainly depends on superoxide radicals photogenerated from rGO-HoVO4-TiO2 under visible light illumination. The antibacterial activity was investigated against Staphylococcus aureus, staphylococcus pyogenes, Bacillus subtilis, and Escherichia coli and the catalyst has good to moderate activity.
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Nickel-substituted copper ferrite nanoparticles (NP) (Cu1-xNixFe2O4) were prepared using a cost-effective hydrothermal method. X-ray diffraction (XRD) pattern revealed a single-phase ...cubic spinel structure. The increase in lattice parameters and decrease in crystallite size are associated with the replacement of Cu ions by Ni ions in the host lattice of copper ferrite. The optimized Cu0.95Ni0.05Fe2O4 composition was subsequently annealed at 750 °C and 850 °C for further studies. Fourier transform infrared (FT-IR) analysis shows the existence of two promising fundamental adsorption peaks at 465 and 582 cm−1, related to the metal ion stretching vibrations at the tetrahedral (A) and octahedral (B) sites, respectively. The local disorder at both the A and B sublattices upon the incorporation of Ni was observed from the Raman analysis. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) images shows the formation of agglomerates composed of nano-sized spherical particles. A high Barrett-Joyner-Halenda (BJH) surface area was achieved 17.25 m2/g with a particle stability of −11.1 mV obtained by the zeta potential. Both the dielectric loss and dielectric constant are decreased, whereas the AC conductivity gets increased with increasing frequency. The magnetization-field hysteresis curves exhibited ferromagnetic behavior with a pseudo-single domain, and the cyclic voltammetry study revealed a pseudocapacitive trend. This study highlights the importance of Ni substitution to control the physicochemical properties of spinel-phase CuFe2O4 for diverse applications, such as energy storage and lithium-ion batteries.
In this study, nickel molybdate nanosphere agglomerates with enhanced electrochemical performance were prepared using a rapid, time-saving, and scalable microwave combustion method by doping with ...different concentrations of La, and the effect of dopants on their structural, morphological, and electrochemical properties were investigated. Structural analyses demonstrated that the La dopant influenced the phase transformation from α-to β-NiMoO4. The electrochemical behaviors of all samples were tested in 3 M KOH electrolyte. The maximum specific capacitance obtained for 5% La doped NiMoO4 was 1264.64 F g−1 at 1 mA cm−2, which was almost 2.6 times higher than that for the pristine NiMoO4. The higher specific capacitance may have been due to the larger active surface area and greater abundance of reactive sites which depends on the morphological characteristics. A device fabricated with the 5% La doped sample had a maximum specific capacitance of 92.1 F g−1 and an energy density of 25.1 Wh kg−1 at 1 mA cm−2. The power density of the device was 5.3 kW kg−1 at a high current density of 25 mA cm−2, and 81.74% was retained after 10,000 cycles, thereby demonstrating the great potential for using this material in high-end energy storage applications.
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•Lanthanum doped Nickel molybdate has been successfully prepared by microwave combustion method.•Phase transfer from α to β phase-NiMoO4 has been observed while increasing dopant concentration.•5% La–NiMoO4 revealed high Csp of 1264.64 F g−1 at 1 mA cm−2 with good retentivity of 98.86% after 5000 cycles.•FLN//AC device displayed a high energy and power density of 25.1 W h kg−1 and 5.83 kW kg−1.
Photo-degradation mechanism of MB dye using sub-10 CdS/RGO nanocomposites under visible (sun) light irradiation.
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•Sub-10 sized CdS NPs evenly embedded on RGO matrix by thermal ...decomposition method.•Single source (CdDTC2) as precursor source for sub-10 CdS NPs.•The sub-10 CdS/RGOnanocomposites showed excellent photocatalytic activity against standard textile dye solutions.•CdS/RGO nanocomposites showed good reusability after 4 cycles.
Quantum dots (QDs) sized sub-10 nanometer (nm) cadmium sulfide (CdS) nanoparticles (NPs) embedded graphene sheets photocatalyst expected significant interest owing to their tunable band gap and high surface to volume ratio. Here demonstrate a single source precursor cadmium diethyldithiocarbamate (CdDTC2) used in presence of reduced graphene oxide (RGO) as template to synthesis sub-10 nm CdS NPs embedded graphene sheet by thermal decomposition method under optimized experimental conditions. The resulting CdS sub-10 NPs modified RGO was characterized with various analytical methods including XRD, HRTEM, UV, FTIR, Raman, XPS, SEM and EDX with mapping. The incorporation of sub-10 CdS NPs uniformly loaded on both sides of RGO was observed by HRTEM micrographs. The photocatalytic performance of the CdS/RGO was studied using a standard textile dye methylene blue (MB) under direct sun light exposure. The results proved that CdS/RGO catalyst exhibit an enhanced degradation rate than the pure CdS NPs. Electrochemical impedance spectroscopic method was employed to examine the prepared CdS/RGO nanocomposites. Results illustrate to CdS species on the surface of RGO can efficiently hasten the separation and postponed the recombination rate in transfer of photo-excited charge carriers. Also, sub-10 CdS/RGO nanocomposites have high surface area and the present method can be used for the preparation of CdS/RGO in large scale.
This attempt reports on cobalt oxide (Co
3
O
4
) nanoparticles (NPs) prepared through the traditional chemical reflux method to examine the behavior of supercapacitor performance. The synthesized NPs ...were characterized using several analytical tools such as ultraviolet-visible spectroscopy (UV), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) pattern, and scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX). Moreover, the electrochemical performance was analyzed using galvanostatic charge and discharge studies (GCD), cyclic voltammetry (CV) studies as well as electrochemical impedance spectroscopy (EIS). The cubical phase of Co
3
O
4
was identified from the XRD pattern and also the average crystalline size was measured by Scherrer’s equation. FTIR confirmed the functional group of Co
3
O
4
NPs. SEM images revealed the hexagonal-shaped nanoflakes-like morphology of the sample. From the elemental analysis, the formation of pure Co
3
O
4
NPs by means of high purity and composition ratio of cobalt with oxygen was found. Vibrating sample magnetometer (VSM) plot scrutinized the magnetic performance of Co
3
O
4
NPs
.
The Co
3
O
4
NPs modified electrode has delivered maximum specific capacitance as 1413 Fg
−1
at a current density of 1 Ag
−1
which maintains tremendous cycling stability within the retention ratio of 98.4% after 1000 cycles.
Graphical Abstract
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