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a XRD pattern of WO3 nanoparticles, b variation of grain size as a function of microwave power, c schematic representation for orthorhombic structure (WO3·H2O) and d monoclinic structure (WO3)
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A novel, energy efficient and facile one step microwave irradiation method has been adopted to prepare the WO3 nanostructures without using any post annealing process. The WO3 nanoparticles were synthesized from tungstic acid and sodium hydroxide mixed aqueous solutions exposed for 5 min to microwave radiation at four different powers, namely 180,...
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... Diffuse reflectance spectroscopy was used to assess the samples' frequency gap (DRS). Using the Kubelka-Munk equation, these spectra were utilized to determine the optical band gap energy (Eg) [25]. Furthermore, the decreased photoluminescence (PL) intensity of 5-Zn@NiFe 2 O 4 may be attributed to a decrease in the recycling of electron-hole pairs, potentially enhancing the photocatalytic efficiency. ...
The present study focuses on employing a rapid, eco-friendly, economical, and sustainable approach to produce pure and zinc (Zn)-doped nickel ferrite (NiFe2O4) nanoparticles. The nanoparticles were synthesized by a green synthesis approach that utilized an extract from Hibiscus rosa-sinensis. The obtained samples were analyzed using XRD, TEM, FTIR, UV-DRS, PL, and XPS to determine their characteristics. The PXRD pattern exhibits the coexistence of spinel cubic and cubic symmetry phases. The optical band gap values of the synthesized materials were measured to be 1.55 eV and 1.92 eV for NiFe2O4 and Zn-doped NiFe2O4 nanoparticles, respectively. The values were derived using Tauc’s relation. The BET study determined that the generated Zn-doped NiFe2O4 had a surface area of 135.72 m²/g. The nickel ferrite nanoparticles, containing 5% zinc by weight, exhibited exceptional photocatalytic efficiency in decomposing methylene blue (99.9%) and malachite green (76.5%) dyes, respectively. The results suggest that the photocatalysts produced showed a highly efficient photodegradation process with a rapid reaction rate, which can be attributed to the effective separation and transfer of charge carriers generated by light. The samples were further characterized by measuring their photodynamic response and electron impedance spectra.
... Since the band gap energy of Ag is lower than the one that transfers band of rGO, the inclusion of Ag nanoparticles improves the rate of charge carrier segregation and reduces electron-hole recombination, further increasing efficiency. The following first-order formula [35] was used to predict the kinetics of the degrading processes. A 0.0985 min −1 rate constant for MB and a 0.0542 min −1 rate variable for 4-NP were determined for the Ag-CuFe 2 O 4 @rGO composite. ...
This study aimed to synthesize a new magnetic photocatalytic nanosystem composed of Ag-CuFe2O4@rGO and to investigate its photodegradation efficiency for two organic pollutants of methylene blue (MB) 4-nitrophenol (4-NP) under visible light irradiation. The synthesized Ag-CuFe2O4@rGO nanocomposites were fully characterized by XRD, TEM, HRTEM, XPS, FTIR, UV and PL analysis which shows well controlled small sized (∼ 10 nm from Scherrer formula) CuFe2O4 NPs with dense and compact loading over rGO sheets. XRD results reveal that cubic spinel structure of CuFe2O4 with nanoparticles (5–10 nm) in shape, which is uniformly, decorated on the surface of the rGO sheets. The band gap energy values of CuFe2O4, Ag-CuFe2O4 and Ag-CuFe2O4@rGO nanoparticles are calculated as 2.76, 2.27 and 2.03 eV, respectively. After incorporation of Ag and rGO into CuFe2O4, the specific surface area was significantly improved to 154 m²/g for Ag-CuFe2O4@rGO nanocomposite. Upon inclusion of the photocatalysts, photodegradation efficiency increased and the Ag-CuFe2O4@rGO composite showed the highest efficiency towards MB (99.5%) and 4-NP (88.7%) followed by the Ag-CuFe2O4. With addition of rGO, the electron-hole recombination declines, thus resulting in a more optimum photocatalytic performance. The rate constant of Ag-CuFe2O4@rGO composite was found to be 0.0985 min⁻¹ for MB and 0.0542 min⁻¹ for 4-NP, respectively. Moreover, the effect of pH, catalyst dosage, and long term stability was thoroughly determined. The improved performance could be attributed to the positive synergistic effect between CuFe2O4 nanoparticles and rGO. The samples were further evaluated by EIS and dynamic photoresponse in order to identify the charge transfer efficiency. The improved photocatalytic mechanism was also explained briefly.
... These results indicate the thermal stability of the prepared tungsten oxide nanostructures in the 400°C-700°C temperature range. [25]. This result is in agreement with the previously reported works [26]. ...
Present work primarily aims to study the near infrared (NIR) reflecting property of tungsten oxide nanostructures synthesized using hydrothermal method. As-synthesized hydrated tungsten oxide (WO3. H2O) sample was subjected to calcination at temperatures 300, 600, 700, 800 and 900 °C respectively for 1 hour and corresponding NIR reflecting performance of the obtained anhydrous tungsten oxide (WO3) nanostructures was analyzed using spectrophotometer. Thermal, structural, morphological, compositional and photoluminescence properties of the nanostructures were also characterized. Moreover, color variation of all samples was identified using CIE L*a*b* color analysis. The sample calcined at 600 °C showed a remarkable NIR reflectance of 91 % with color coordinates L* = 70.21, a* = - 4.28, b* = 22.47, h* = 100.78°, and C* = 22.87. Particle size and oxygen vacancies were found to play a significant role in NIR reflectance ability of tungsten oxide. The present work provides new insight into developing NIR reflecting tungsten oxide powders to be used as environmentally friendly cool materials for buildings and automobiles with energy saving performance.
... The relevant parameters including Brunauer-Emmett-Teller (BET) surface area (SBET), total pore volume (VTot), and average pore size (D av ) are listed in Table 1. Type-IV isotherms were shown to exist for the Sm 2 O 3 -MWCNTs composite, and a minor loop of hysteresis was identified around 0.7 and 0.95, indicating the existence of mesopores in the surface structure [22][23][24][25]. The S BET of the Sm 2 O 3 -MWCNTs composite is 212.5 m 2 g −1 , and the V Tot is 0.756 cm 3 g −1 , both of which are superior. ...
Hybridizing hierarchically structured Sm2O3 with multi-walled carbon nanotube (MWCNTs) is highly desirable for improving the performance of Sm2O3-based gas sensors. In this work, we developed a simple solvothermal method combined with heat treatment for the preparation of flower-like Sm2O3/MWCNTs nanocomposites with a flexible three-dimensional nanostructure. The characterization results showed that 4–8 μm Sm2O3 flower-like structures, formed by Sm2O3 nanosheets, were attached to the MWCNTs surface. The Sm2O3-MWCNTs composite possesses a SBET of 212.5 m2g−1 and higher VTot of 0.756 cm3g−1. Gas sensors based on the Sm2O3/MWCNTs nanocomposites exhibited a greater response, better selectivity, lower operating temperature, and good recovery towards acetone compared with pure Sm2O3. Additionally, the sensors show a total recovery of their baseline resistance and reasonable response and recovery times. 5.0 wt% MWCNT-doped Sm2O3 sample is the most sensitive sensor towards LPG and ethanol and the related response value are 18.2 and 14.3. Moreover, the Sm2O3/MWCNT hybrid sensor delivers a response and recovery time of 7 and 10 s, respectively. In addition, the fabricated sensor showed high stability, which is conducted by long period (60 days) sensing response for both gases. The improved mechanism of the fabricated sensor was also discussed in detail.
... The Brunauer-Emmett-Teller (BET) surface areas of TiO 2 and TiO 2 /PEDOT:PSS were 56.4 and 101 m 2 /g, respectively. It is evident that a hysteresis loop exists in the TiO 2 /PEDOT:PSS isotherm when the relative pressure is between 0.4 and 0.8, meaning that mesopores [39][40][41] exist in the TiO 2 /PEDOT:PSS nanocomposites. Further, the mesoporous nature of the samples was determined by Barrett-Joyner-Halenda (BJH) pore size curve (Fig. 5b) and the values are 12 and 27 nm for TiO 2 and TiO 2 /PEDOT:PSS, respectively. ...
In this report, TiO2 nanoparticles (NPs) functionalized with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composites films have been developed for use in organic solar cells (OSCs). The TiO2∕PEDOT:PSS films were characterized by X-ray diffraction, Raman spectroscopy, UV–Vis, PL, and microscopy techniques. Atomic force microscopy (AFM) images showed that the addition of PEDOT significantly changes the morphology of the TiO2 films, with loss of uniformity and increase in surface roughness. The TiO2∕PEDOT:PSS OSC showed the best performance and displayed power conversion efficiency (PCE) of 7.24%, much higher than the bare TiO2 (4.25%) OSC device. This enhanced performance is mainly driven by the improvements in the short-circuit current (~ 16.9 mA/ cm2) as well as the fill factor (~ 72%) that is ascribed to the PEDOT:PSS after incorporated with TiO2, which improved the contact between the electrolyte and electrode layer. Consequently, extraction efficiency of the photogenerated holes is increased, while recombination probability of holes and electrons in the photoactive layer is decreased. The films were further evaluated for electrochemical characterizations and the improved solar cell mechanism of the present OSCs are also discussed in details.
... Tabla 2). Mientras que para el caso del polvo de WO3 obtenido en ambiente de Ar+H2O (véase Figura 8b) aparece otra banda más a las antes mencionadas ubicada en 338 cm -1 perteneciente a la vibración W-O [31], [32], [33]. Al igual que la muestra de WO3 obtenida en ambiente de Ar+H2O, la muestra de WO3 obtenida en aire presenta las mismas bandas, pero en este caso la intensidad de las bandas aumenta de manera considerable. ...
1 Implementación de un sistema de depósito químico en fase vapor asistido por filamento caliente (HFCVD) para la obtención del semiconductor trióxido de tungsteno (WO3) Implementation of a hot filament assisted chemical vapor deposition system (HFCVD) to obtain the semiconductor tungsten trioxide (WO3) Resumen Se obtuvieron polvos de trióxido de tungsteno (WO3) mediante un sistema de HFCVD (Hot Filament Chemical Vapor Deposition). Los polvos exhibieron tres diferentes coloraciones (azul rey, azul cielo y amarillo), debido al cambio del gas precursor usado (argón (Ar) o argón con vapor de agua (Ar+ H2O) o aire). Los polvos fueron evaluados por Difracción de Rayos-X (DRX) para la determinación de su estructura cristalina, su morfología fue observada mediante Microscopia Electrónica de Barrido (MEB), la composición química elemental se obtuvo por Espectroscopia de Energía Dispersiva (EDS). Por último, se analizaron las bandas de los enlaces presentes en el material con ayuda de Espectroscopia RAMAN. Estas técnicas lograron evidenciar la presencia del trióxido de tungsteno en los polvos obtenidos. Palabras clave: semiconductores, trióxido de tungsteno, HFCVD. Abstract Tungsten trioxide (WO3) powders were obtained using a HFCVD (Hot Filament Chemical Vapor Deposition) system. Three different colors (royal blue, sky blue and yellow) due to the change of the implemented precursor gas (argon (Ar) or argon with water vapor (Ar+ H2O) or air) were obtained. The powders were evaluated by X-Ray Diffraction (XRD) to determine the crystalline structure, the morphology was studied by Scanning Electron Microscopy (SEM), the elemental chemical composition was obtained by Energy Dispersive Spectroscopy (EDS). Finally, study of the structure was analyzed by RAMAN Spectroscopy. These techniques were able to demonstrate the presence of tungsten trioxide in the powders obtained.
... The peak at 33.9 eV confirms the presence of W 5+ species. 53,54 The O 1s core peak at 530.31 eV can be resolved to terminal oxygen (=O) and the link oxygen (-O-). The peak at 529 eV can be attributed to the presence of -OH. ...
Melatonin is an important hormone that is clinically significant due to its physiological role, making its detection in real samples crucial for monitoring body function. Compared to other traditional approaches, electrochemical sensors have advantages such as high sensitivity, point-of-care analysis, rapid response time, ease of use, and cost-effectiveness. Recently, natural polymer-based biocomposites such as chitosan, gum acacia, xanthan gum, and chitinhave been employed due to their low cost, biocompatibility, and high surface area for biosensing applications. We have investigated Tungsten oxide (WO3) nanospheres decorated with functionalized chitosan (FCH) for the detection of melatonin. The functionalization of chitosan introduced plentiful amine groups and inter-hydrogen bonding provided necessary stability for the formation of WO3/FCH biocomposite. Further, the electroanalysis confirmed the excellent electrocatalytic performance of the biocomposite towards melatonin in with a limit of detection of 4.9 nM. The proposed nanocomposite exhibited excellent selectivity, reproducibility, stability, and its practical reliability was evaluated real samples. Herein, functionalization of introduced large density of amine groups that offered efficient binding affinity with WO3.and improved the conductivity of the nanocomposite for a highly sensitive melatonin detection. The proposed modified electrode will be a suitable platform for futuristic clinical biosensing applications.
... 13,15,[18][19][20] Recently, microwave-based processing is found to be an effective technique in producing various nanomaterials with enhanced properties due to rapid heating rate, shorter processing time, and uniform distribution of heat. [21][22][23][24] Also, microwave-based processing was widely used in post-processing of the variety of nanomaterials to enhance the properties. 25,26 However, producing amorphous silica nanoparticles using rice husks via microwave combustion is rarely reported and it can be a promising method for producing amorphous silica nanoparticles from rice husks for rapidly constructing drug delivery systems at low cost. ...
Amorphous silica nanoparticles are a promising platform for constructing drug delivery vehicles owing to their high biocompatibility and favorable surface chemistry. In the current study, we report the preparation of amorphous silica nanoparticles using rice husk biowaste via easy and rapid microwave‐assisted combustion. The obtained results from various characterizations indicate that the prepared sample is an amorphous form of silica nanoparticles having sizes 50–80 nm with high purity. Ciprofloxacin was used as the model drug and it was released from silica nanocarrier in a controlled and prolonged manner. The ciprofloxacin release kinetics was investigated using the Higuchi model and Ritger‐Peppas model which corroborate that different process like desorption, diffusion, and surface erosion may be involved in the release of ciprofloxacin from the prepared silica nanocarrier. The antibacterial susceptibility test revealed that the ciprofloxacin loaded silica nanocarrier exhibit a bacterial inhibition zone about 32 ± 4 and 44 ± 3 mm against Escherichia coli and Staphylococcus aureus, respectively. This study can be useful to develop a versatile nanocarrier with controlled delivery of ciprofloxacin to treat different types of bacterial infections.
This study used zinc/iron acetate (as a precursor) and a carboxylic variant of activated carbon (as a matrix) to create nanostructured zinc ferrite (ZnFe2O4). Carboxylic derivative (AC–COOH) of activated carbon was obtained by nitric acid oxidation. Then, enhanced activated carbon's surface was impregnated with ZnFe2O4. ZnFe2O4 nanoparticles with a size range of 25–35 nm and a surface area of 165.8 m2g−1 were proven to have been achieved after the ZnFe2O4 nanostructure was characterized by XRD, FESEM, TEM, UV, PL, BET, and XPS. Using the same testing circumstances, the optimized photocatalyst with 10 wt.% ZnFe2O4 inserted AC demonstrated the best degrading efficeicny to methylene blue (99%) and Reactive red (94%). The Langmuir–Hinshelwood hypothesis, which states that the dye concentration is a first-order function of time, was validated by kinetic investigations. The photocatalyst was shown to be stable after 7 cycles of recycling under optimal circumstances in a study of the reusability of a 10-ZnFe2O4/AC photocatalyst. In addition, PL, TRPL, EIS, and transient-photocurrent response all provide strong evidence for the efficient charge separation in ZnFe2O4/AC.
