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The present research article is about the visible light photocatalytic degradation of Methylene Blue (MB) by aqueous heterogeneous medium containing orthorhombic phase of nanocrystalline (NCs) molybdenum oxide (MoO3). The two different oxidation forms of molybdenum oxides formed at annealing temperatures of 90 °C and 400 °C are Mo17O47 and α-MoO3 n...
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... The dyes MO and MB have unique physical and chemical properties with the structural formulas shown in Figure 1. [42]. ...
In this study, the polar root extract of Cyperus scariosus R.Br. was used for the biogenic synthesis of ZnO NPs. The results of this study show that ZnO NPs have a spherical structure with an average size of 85.4 nm. The synthesized catalysts were tested for their photocatalytic activity by degrading methyl orange and methylene blue under sunlight. Improved degradation efficiencies of 79.44% and 84.92% were achieved within 120 min. ZnO NPs exhibited strong antibacterial activity against both Gram-positive Listeria monocytogenes (18 mm) and Staphylococcus epidermidis (20 mm) and Gram-negative strains of Escherichia coli (16 mm) and Bordetella bronchiseptica (14 mm), as shown by the inhibition zones, which were comparable to the positive control (ceftriaxone) but larger than the plant root extract. ZnO NPs showed high antioxidant activity, as a ferric-reducing antioxidant power assay value of 66.29 µg (AAE µg·mL⁻¹) and a DPPH value of 57.44 µg (AAE µg·mL⁻¹) were obtained at a concentration of 500 µL, which was higher than those of the C. scariosus root extract. Quantification of the total phenolic and flavonoid content yielded values of 57.63 µg (GAE µg·mL⁻¹) and 70.59 µg (QCE µg·mL⁻¹), respectively. At a concentration of 500 μL (1 mg·mL⁻¹), the tested nanoparticles (NPs) showed a greater anti-inflammatory effect (84.12%) compared to the root extract of C. scariosus (34.39%). Overall, our findings highlight the versatile properties of green synthesized ZnO NPs and demonstrate their potential for environmental remediation and antimicrobial formulations, as well as promising candidates for further investigation in biomedical fields such as drug delivery and therapy.
... It is observed that the decrease in the lattice parameters seem to be relatively defensible as ionic radii of Ag 3+ is higher than that of Mo 6+ . The unit cell volume slightly increases and its micro strain decreases than that of pure MoO3 which is due to the contamination of more supportive in non-equilibrium positions [18,19]. However , the unit cell volume seems to be decreases for 10 to 15% Ag 3+ doping which may be due to mismatch between the radii of Ag 3+ and Mo 6+ . ...
MoO3 have been widely investigated for their applications ranging from electronics to energy storage. Orthorhombic structured MoO3 thin films were prepared on a glass substrate. The Ag doped materials to add the MoO3 in different concentrations (1%, 3%, 5%) at Wt% with MoO3 precursor and synthesis was done using the spray pyrolysis method. X-ray diffraction revealed the incorporation of Ag in the MoO3 orthorhombic structure. FE-SEM images showed more dispersive and rod shapes than Agi-doped MoO3 and pure MoO3 respectively. The jet nebulizer spray pyrolysis technique for fabrication of n-Ag: MoO3/p-Si photodiodes makes it suitable for good response photo-detecting applications.
... There are several approaches reported for the preparation of Mo oxides such as hydrothermal, chemical precipitation, and anodization methods. Rajiv et al. [81] studied the photocatalytic activity of Mo oxides composed of α-MoO 3 and Mo 17 O 47 phases prepared by hydrothermal method at 90 • C and 400 • C, respectively. It was found that the degradation efficiency toward MB dye (30 ppm) of prepared Mo oxides reached 95% under visible light irradiation for 90 min. ...
In this work, a nanopowder of porous molybdenum (Mo) oxides with different polymorphs were prepared by anodizing the Mo sheet in ethylene glycol solution containing fluoride at 60, 70, and 80 V for 30 min. Synthesized Mo oxides showed remarkable changes in their structural parameters and morphology upon the anodization voltage which were confirmed using X-ray diffraction, energy dispersive X-ray, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, N2 adsorption-desorption, and field emission scanning electron microscopic. Anodized Mo is composed of α-MoO3, β-MoO3, β-MoO2, and β-Mo9O26 phases. Synthesized Mo oxides were used, as a catalyst, for the photodegradation of methylene blue (MB), and results were compared to the literature. The maximum observed efficiency, ∼65%, towards MB was achieved using anodized Mo at 70 V (MO70) under UV–visible irradiation for 85 min. The N2 adsorption-desorption analysis revealed that MO70 exhibits the smallest particle size and greatest surface area among other samples. The performance of MB adsorption was investigated using several kinetic adsorption models and the pseudo-second-order model being the ideal one. The maximum adsorption constant is 1.4 × 10−2 g/(mg min) and the amount of MB that degraded at equilibrium is 5.52 mg/g for MO70. The anodization of Mo generated various polymorphs semiconductors which provide an excellent platform for the removal of toxic organic dyes from the wastewater.
... , where E VB is the VB edge potential, X is the electronegativity of the semiconductor (a and b are the atomic number of compounds), E e is the energy of free electrons vs hydrogen (4.5 eV), Eg is the band gap energy The photogenerated electrons and holes are separated at the heterojunctions and are involved in the MB oxidation process and the MoO 3 /TiO 2 -SiO 2 composites exhibit higher photocatalytic activity as compared to MoO 3 . A signi cant improvement of the rate constant (k = 0.0645 min -1 ) was achieved, not only compared to the MoO 3 studied in this study, but also to other MoO 3 samples in the literature [43,44]. ...
MoO 3 /TiO 2 –SiO 2 layered spherical composites with hierarchical structures have been synthesized via a template and sol-gel methods in which TOKEM-320Y anion exchanger was used as template. The properties of MoO 3 /TiO 2 –SiO 2 spherical composites were characterized by X-ray diffraction, Scanning electron microscopy, Energy-dispersive X-ray spectroscopy, 3D X-ray microtomography, N 2 sorption, Infrared and Raman spectroscopies and ultraviolet spectrophotometry. The photocatalytic activity of MoO 3 /TiO 2 –SiO 2 composites was evaluated by photocatalytic degradation of methylene blue (MB) aqueous solution under irradiated with an I 2 excilamp (λ max = 312 nm) and its photoabsorption energy properties are related to the interaction between TiO 2 –SiO 2 and MoO 3 which occurs through oxygen in Ti-O-Mo and Si-O-Mo. The layered hierarchical structure results in lower oxygen vacancy concentrations in composites (0.0425) and a reduced bandgap width (2.58 eV in compare to 3.18 eV for MoO 3 spheres), which increases the composite's absorption of light in the visible light regime (λ absorption edge is 480.5 nm). Photocatalytic degradation of the MB dye followed the pseudo-first-order-kinetics. Degradation product analysis was done using the HPLC-MS technique. The dye degradation is initiated by demethylation of the molecule and lead to formation of azure A, B and C and thionin. The results showed that MoO 3 /TiO 2 –SiO 2 composites exhibited a much higher photocatalytic activity (rate constant is 0.0645 min ‒1 ) than that of MoO 3 spheres and other MoO 3 samples in the literature. This investigation demonstrates that MoO 3 /TiO 2 –SiO 2 layered spherical composites is a promising candidate material for photocatalytic decomposition of organic dyes in textile waste water which are considered as one of the greatest threats to the environment.
... Orthorhombic molybdenum trioxide (α-MoO 3 ) with a layered crystal structure has been recognized as one of the promising electrode materials for energy storage (Pomerantseva et al., 2019;Xie et al., 2020). In the synthesis of MoO 3 , various reaction parameters such as the molybdenum precursor, solvent medium, reaction time, and temperature allow for control over the morphology of the product (Pomerantseva et al., 2019;Mendez-Vivar et al., 1990), with various MoO 3 nanostructures such as nanoparticles (Rajiv Chandar et al., 2020), nanowires (Joseph et al., 2019;Yu et al., 2020;Zhou et al., 2010), nanopapers (Yao et al., 2016;Zhao et al., 2020), and nanobelts (Wang et al., 2005;Li and Liu, 2013;Jiang et al., 2013) being reported. To improve the electrochemical properties of MoO 3 , strategies such as introducing oxygen vacancies (Kim et al., 2017), tuning the interlayer spacing , and incorporating conductive materials have been proposed. ...
A capacitance increase phenomenon is observed for MoO3 electrodes synthesized via a sol-gel process in the presence of dopamine hydrochloride (Dopa HCl) as compared to α-MoO3 electrodes in 5M ZnCl2 aqueous electrolyte. The synthesis approach is based on a hydrogen peroxide-initiated sol-gel reaction to which the Dopa HCl is added. The powder precursor (Dopa)xMoOy, is isolated from the metastable gel using freeze-drying. Hydrothermal treatment (HT) of the precursor results in the formation of MoO3 accompanied by carbonization of the organic molecules; designated as HT-MoO3/C. HT of the precipitate formed in the absence of dopamine in the reaction produced α-MoO3, which was used as a reference material in this study (α-MoO3-ref). Scanning electron microscopy (SEM) images show a nanobelt morphology for both HT-MoO3/C and α-MoO3-ref powders, but with distinct differences in the shape of the nanobelts. The presence of carbonaceous content in the structure of HT-MoO3/C is confirmed by FTIR and Raman spectroscopy measurements. X-ray diffraction (XRD) and Rietveld refinement analysis demonstrate the presence of α-MoO3 and h-MoO3 phases in the structure of HT-MoO3/C. The increased specific capacitance delivered by the HT-MoO3/C electrode as compared to the α-MoO3-ref electrode in 5M ZnCl2 electrolyte in a −0.25–0.70 V vs. Ag/AgCl potential window triggered a more detailed study in an expanded potential window. In the 5M ZnCl2 electrolyte at a scan rate of 2 mV s⁻¹, the HT-MoO3/C electrode shows a second cycle capacitance of 347.6 F g⁻¹. The higher electrochemical performance of the HT-MoO3/C electrode can be attributed to the presence of carbon in its structure, which can facilitate electron transport. Our study provides a new route for further development of metal oxides for energy storage applications.
... The peaks around 864 cm -1 is due to the stretching mode of doubly coordinated oxygen (νO-Mo2) and the peak at 995 cm -1 is attributed to the stretching mode of terminal oxygen ν(O=Mo). The peak at 1126 cm -1 is due to the bending mode of Mo-OH bonds δ(Mo-OH) [18,19]. Thus, the formation of MoO3 thin films is confirmed using FT-IR spectra. ...
In this study, molybdenum trioxide (MoO3) thin films were coated with various Mo concentrations 1, 2, 3 and 4 wt.% referred as L1, L2, L3 and L4 respectively on to the silica substrate calcined at 450 ºC by a facile, rapid cost-effective and a custom-made jet nebulizer spray pyrolysis (JNSP) technique. The concentration impact on the structural, morphological and compositional parameters were examined by XRD, FESEM, EDX, FTIR and Raman studies. The XRD peaks confirmed the presence of the orthorhombic phase of MoO3 (α-MoO3) in the prepared films. FESEM images depicted their nanorod structured morphology. EDX spectra confirm the presence of elements such as oxygen (O) and molybdenum (Mo). Molecular fingerprint of the samples were diagnosed by probing their molecular vibrations through the Raman Spectroscopy. Vibrational frequencies of the bonds in the samples was investigated by FTIR. The I-V measurements were analyzed in light and dark conditions for the n-MoO3/p-Si junction diode.
In this study MoO3/TiO2–SiO2 layered spherical composites, having hierarchical structure, were synthesized on TOKEM-320Y anion exchanger template using by sol-gel methods. Properties of MoO3/TiO2–SiO2 composites were characterized by XRD, EDS, SEM, 3D X-ray microtomography, Raman, IR, DRS, BET, and PL techniques. The SEM, 3D X-ray microtomography and EDS analysis showed hollow spherical composites with diameters ranging from 200 to 400 μm with core/shell structure. The formation of TiO2–SiO2 shell on the MoO3 core results in lower oxygen vacancy concentrations in composite (0.0425) and a reduced bandgap width (2.56 eV in compare to 3.19 eV for MoO3 sample, which was analyzed through the UV–VIS DRS method). The performance of MoO3/TiO2–SiO2 composites was evaluated by photocatalytic degradation of methylene blue (MB) aqueous solution irradiated with an I2 excilamp (λmax = 312 nm). The photoabsorption energy properties of MoO3/TiO2–SiO2 composites are related to the interaction between TiO2–SiO2 and MoO3 which occurs through oxygen in Ti-O-Mo and Si-O-Mo. The MoO3/TiO2–SiO2 composites exhibited a much higher photocatalytic activity (rate constant is 0.0645 min‒1, degradation efficiency is 93% (20 min). This work demonstrates the relation between the formation of heterostructure in core/shell composite and its photocatalitic activity, providing fundamental guidance to improve photocatalytic performance of materials.
A MoO 3-x /BiVO 4 nanoporous heterojunction photoanode is designed to provide an electron "highway" for charge separation and transport, leading to a high and stable photocurrent density of 4.81 mA cm-2 for photoelectrochemical water splitting. Songcan Wang, https://teacher.nwpu.edu.cn/scwang.html ABSTRACT Owing to the relatively short hole diffusion length, severe charge recombination in the bulk of bismuth vanadate (BiVO4) is the key issue for photoelectrochemical (PEC) water splitting. Herein, we design a nanoporous MoO3-x/BiVO4 heterojunction photoanode to promote charge separation. The efficient electron transport properties of oxygen deficient MoO3-x and the nanoporous structure are beneficial for charge separation, leading to a significantly enhanced PEC performance. The optimized MoO3-x/BiVO4 heterojunction photoanode exhibits a photocurrent density of 5.07 mA cm-2 for Na2SO3 oxidation. By depositing FeOOH/NiOOH dual oxygen evolution cocatalysts to promote surface kinetics, a high photocurrent density of 4.81 mA cm-2 can be achieved for PEC water splitting, exhibiting an excellent applied bias photon-to-current efficiency of 1.57%. Moreover, stable overall water splitting is achieved under consecutive light illumination for 10 h. We provide a proof of concept for the design of efficient BiVO4-based heterojunction photoanodes for stable PEC water splitting.
