Porous V2O5/TiO2 Nanoheterostructure Films with Enhanced Visible-Light Photocatalytic Performance Prepared by the Sparking Method

Investigation of structural, electronic and optical properties of two-dimensional MoS2-doped-V2O5 composites for photocatalytic application: a density functional theory study

In the present research, the structural, electronic and optical properties of transition metal dichalcogenide-doped transition metal oxides MoS₂-doped-V₂O₅ with various doping concentrations (x = 1-3%) of MoS₂ atoms are studied by using first principles calculation. The generalized gradient approximation Perdew-Burke-Ernzerhof simulation approach is used to investigate the energy bandgap (E_g) of orthorhombic structures. We examined the energy bandgap (E_g) decrement from 2.76 to 1.30 eV with various doping (x = 1-3%) of molybdenum disulfide (MoS₂) atoms. The bandgap nature shows that the material is a well-known direct bandgap semiconductor. MoS₂ doping (x = 1-3%) atoms in pentoxide (V₂O₅) creates the extra gamma active states which contribute to the formation of conduction and valance bands. MoS₂-doped-V₂O₅ composite is a proficient photocatalyst, has a large surface area for absorption of light, decreases the electron-hole pairs recombination rate and increases the charge transport. A comprehensive study of optical conductivity reveals that strong peaks of MoS₂-doped-V₂O₅ increase in ultraviolet spectrum region with small shifts at larger energy bands through increment doping x = 1-3% atoms of MoS₂. A significant decrement was found in the reflectivity due to the decrement in the bandgap with doping. The optical properties significantly increased by the decrement of bandgap (E_g). Two-dimensional MoS₂-doped-V₂O₅ composite has high energy absorption, optical conductivity and refractive index, and is an appropriate material for photocatalytic applications.

Effect of magnetic field on improvement of photocatalytic performance of V2O5/TiO2 nanoheterostructure films prepared by sparking method

Our porous V2O5/TiO2 nanoheterostructure films (with a Ti/V atomic ratio of 1:1) were fabricated via a single-step sparking method using a strong magnetic field (0.5 T) without annealing requirement for the first time. We found that the magnetic flux arrangement has effect on film crystallization, unique morphology, large specific surface area, and surprisingly controllable phase structure of the films. An amorphous TV film was transformed to the TiO2 (anatase/rutile) phase (for TVN) and V2O5-VO2 mixed-phase (for TVH) without destroying the mesopores from an annealing process. Moreover, the TVH sample able to improve the degradation rate up to 270% compared with pre-annealed TV films and up to 30% with post-annealed (400 °C) TVA films. In this paper, the influence of magnetic flux arrangement on structural, morphological, optical, and photocatalytic properties of prepared sample have been investigated and reported.

Studies on the Characteristics of Nanostructures Produced by Sparking Discharge Process in the Ambient Atmosphere for Air Filtration Application

Among the various methods for the preparation of nanoparticles, a sparking process at atmospheric pressure is of interest because it is a simple method for producing nanoparticles ranging from a few nanometer-sized particles to agglomerated film structures. In this research, we studied the effects of metal electrode properties on nanoparticle sizes. The experiments were carried out by applying a high voltage to different metal sparkling tips. The transfer of energies from positive ions and electron bombardments induced the melting and vaporization of electrode metals. Based on this research, we have developed a model to describe the formation of a nanoparticle film on the substrate, placed under the sparking gap, and the nanostructure produced by metal vapor on the sparking electrodes. The model provides a realistic tool that can be used for the design of a large-scale coating and the application of nanoparticles developed by this process for the filtration of PM2.5 mask fabric by air.

Catalysis by Hybrid Nanomaterials

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