Sharif Digital Repository

A green mechanochemical technique has been developed for the synthesis of mixed ammonium silver phosphomolybdate salt, (NH4)1.6Ag1.4PMo12O40.4H2O with sheet-like nanostructure. The reaction was prompted using acetamide/NH4NO3 at room temperature. The change of driving agent to urea at the same conditions led to an epitaxial growth of hierarchical microstructure of this polyoxoanion. The morphological and structural features of the prepared specimens were discussed in detail. The photocatalytic performance of the resulting nanosheets for removing 4-nitrophenol (4-NP) in water under visible light... 

This study describes the synthesis of TiO2/WO3 composite systems with a varying concentration of WO3 by a glucose-template assisted method and demonstrates their round-the-clock photoactivity performance towards the degradation of methanol (MeOH) under illumination and dark conditions. XRD results indicated a biphasic anatase-rutile nature of TiO2, with tunable concentrations with respect to the WO3 loading. WO3 incorporation extended the light absorption of the system towards visible light, increasing the observed photoactivity. The obtained results were further validated using photo-electrochemical investigations such as photocurrent measurements and the impedance response of the systems.... 

Graphene-tungsten oxide composite thin films with sheetlike surface morphology were fabricated and applied in photoinactivation of viruses under visible light irradiation. Using X-ray photoelectron spectroscopy, it was found that the chemically exfoliated graphene oxide sheets incorporated in the tungsten oxide film reduced through a visible light photocatalytic reduction. In addition, annealing the films at 450 °C in air resulted in formation of W-C and W-O-C bonds to obtain graphene-tungsten oxide composite films. The composite films fabricated by this method showed an excellent visible light photocatalytic performance in photoinactivation of bacteriophage MS2 viruses, as compared to... 

Vertically aligned ZnO nanowires (NWs) hybridized with reduced graphene oxide sheets (rGO) were applied in efficient visible light photoinactivation of bacteria. To incorporate graphene oxide (GO) sheets within the NWs two different methods of drop-casting and electrophoretic deposition (EPD) were utilized. The EPD method yielded effective penetration of the positively charged GO sheets into the NWs to form a spider net-like structure, whereas the drop-casting method resulted in only a surface coverage of the GO sheets on top of the NWs. The electrical connection between the EPD-incorporated sheets and the NWs was checked by monitoring the electron transfer from UV-assisted photoexcited ZnO... 

Vertically aligned ZnO@CdS nanorod heterostructure films with various loadings of CdS nanoparticle shell were synthesized and applied in photoinactivation of Escherichia coli bacteria under visible light irradiation. While neither the bare ZnO nanorods (with band-gap energy (Eg) of ∼3.28 eV) under visible light irradiation nor the nanorod heterostructures in dark exhibited any significant antibacterial activity, the ZnO@CdS nanorod heterostructures (with Eg ∼2.5-2.6 eV) could successfully inactivate the bacteria under visible light irradiation. Furthermore, it was found that an optimum loading of the CdS shell (corresponding to the effective thickness less than ∼15 nm) is required to achieve... 

We report the nanoporous Ag2O based on the copper terephthalate metal–organic frameworks (Ag2O/MOF) photocatalyst. Ag2O/MOF nanostructure was formed via oxygen treatment of Ag/MOF nanoparticles. The resulting Ag2O/MOF photocatalysts were characterised by various techniques. Results showed that the synthesised Ag2O/MOF nanocomposite exhibited dramatic separation of photoinduced electron/hole and excellent photodegradation activity under visible light irradiation. The degradation rate of acid blue 92 using Ag2O/MOF nanocomposite is found to be higher than that using pure MOF and Ag/MOF. It was divulged that the photodegradation rate is increased by oxygen treatment of Ag in Ag/MOF structure.... 

MWCNTs/Ag/TiO2NTs plates were synthesized via electrochemical reduction of functionalized multiwalled carbon nanotubes (MWCNTs) on Ag/TiO2NTs. The loading of silver nanoparticles was carried out by electroless reduction of Ag1+ onto TiO2 nanotubes previously formed by anodizing titanium. The SEM analysis revealed that MWCNTs were loaded significantly on the as-prepared Ag/TiO2NTs, where nanoparticles of Ag had grown on the walls of TiO2NTs. The photocatalytic activity of the synthesized plates was evaluated by the photodegradation of Methyl Orange (MO) dye under UV light irradiation. The results indicated that the MWCNTs/Ag/TiO2NTs demonstrated improved efficiency for MO photodegradation in... 

Antibacterial activity of tungsten oxide nanorods/microrods were studied against Escherichia coli bacteria under visible light irradiation and in dark. A two-step annealing process at temperatures up to 390 °C and 400-800 °C was applied to synthesize the tungsten oxide nanorods/microrods on tungsten foils using KOH as a catalyst. Annealing the foils at 400 °C in the presence of catalyst resulted in formation of tungsten oxide nanorods (with diameters of 50-90 nm and crystalline phase of WO3) on surface of tungsten foils. By increasing the annealing temperature up to 800 °C, tungsten oxide microrods with K2W6O19 crystalline phase were formed on the foils. The WO3 nanorods showed a strong... 

A series of reduced graphene oxide/ZnxCd1-xS (RGO/ZnxCd1-xS) nanocomposites (0 < x < 1) with different ratios of Zn/Cd were synthesized via a facile hydrothermal route under optimized experimental conditions and were carefully characterized by various techniques. Because very little is known about the morphology, specific surface area, and crystal phase effects of RGO/ZnxCd1-xS crystals on their photoresponsivity, field-emission scanning electron microscopy (FE-SEM), BET surface area analysis and X-ray diffraction (XRD) data were studied to investigate their effects on photoactivity. Based on the results, a crystal phase transition from a cubic phase in RGO/Zn0.9Cd0.1S to a hexagonal... 

In this study, for the first time a statistical analysis based on the response surface methodology (RSM) was employed to investigate individual and interaction effects of key operating parameters of the photocatalytic degradation under visible-light irradiation using Ag-S/PEG/TiO2. Ag-S/PEG/TiO2 is a visible-light-driven photocatalyst and was synthesized (based on earlier research) by co-doping of TiO2 with silver and sulphur and addition of polyethylene glycol (as a reagent template). In addition, the model pollutant was methylene orange (MO) and the studied operating parameters included the photocatalyst loading, initial concentration of the pollutant, and pH of the solution. The... 

In this study, the interaction effect of K2S2O8 (PDS) and H2O2 (as two powerful oxidants) was investigated on the solar degradation of 2-nitrophenol (2-NF) in the two systems, i.e. absence and presence of Ag/S/TiO2 photocatalyst. Experiments were designed based on the central composite design, and two methods of response surface methodology (RSM) and artificial neural network (ANN) were developed for modeling of the systems. Concentrations of PDS and H2O2 were considered as independent variables and 2-NF degradation efficiency was selected as the response. It was revealed that the predictive capacity of ANN model is more than RSM model according to their corresponding R2, R2 adj RMS, MAE,... 

We report a facile method to synthesize a magnetically separable Pd-rGO/CNT/CaFe2O4 photocatalyst. The incorporation of CNTs into rGO can form a conductive network structure to bridge the gaps between rGO sheets. This conductive network can prevent the restacking of GO nanosheets during the reduction process. Also, for photocatalysis, the aforementioned conjugated network can provide rapid electronic conducting channels. It was found that the Pd-rGO/CNT/CaFe2O4 nanocomposite is an efficient photocatalyst for the Heck-Mizoroki coupling reaction under irradiation of visible light. Interestingly, the electrons which are excited by the photons can be transferred to the palladium nanoparticles... 

We report a facile method to synthesize a magnetically separable Pd-rGO/CNT/CaFe2O4 photocatalyst. The incorporation of CNTs into rGO can form a conductive network structure to bridge the gaps between rGO sheets. This conductive network can prevent the restacking of GO nanosheets during the reduction process. Also, for photocatalysis, the aforementioned conjugated network can provide rapid electronic conducting channels. It was found that the Pd-rGO/CNT/CaFe2O4 nanocomposite is an efficient photocatalyst for the Heck-Mizoroki coupling reaction under irradiation of visible light. Interestingly, the electrons which are excited by the photons can be transferred to the palladium nanoparticles... 

The current study develops a 3D constitutive model for photo-thermal sensitive hydrogels based on free energy decomposition. The hydrogel under study is PNIPAM network with copper chlorophyllin nanoparticle agents attached to the network. The effect of light intensity is considered as a rise in temperature since chlorophyllin nanoparticle agents absorb light irradiation and convert it to heat. Moreover, it is necessary to consider the effect of dissociation of these agents on the hydrogel’s free energy function; therefore, a term is added to the free energy function. After introducing the model, some problems, including the free swelling and uniaxial loading problems, are studied, and the... 

The adverse effect of graphene-titanium oxide composite films (containing sheet-like surface morphology) on Caenorhabditis elegans nematodes (as a model for minuscule animals) was investigated in a solar light-induced photocatalytic process. X-ray photoelectron spectroscopy demonstrated photocatalytic reduction of the chemically exfoliated graphene oxide sheets included in the TiO 2 film. Furthermore, formation of TiC and Ti-O-C bonds in the composite film (obtained through annealing at 450 °C in air) resulted in a substantial delay in the recombination rate of the photoexcited electron-hole pairs and more efficient photocatalytic processes. The composite film showed a type of... 

Two types of unfunctionalized and functionalized multi-wall carbon nanotubes (MWCNTs) were prepared to be applied in fabrication of MWCNT-ZnO nanocomposite thin films with various MWCNT contents. X-ray photoelectron spectroscopy indicated formation of functional groups on surface of the functionalized MWCNTs in the MWCNT-ZnO nanocomposite. Formation of the effective carbonaceous bonds between the ZnO and the MWCNTs was also investigated through photoinactivation of Escherichia coli bacteria on surface of the both unfunctionalized and functionalized MWCNT-ZnO nanocomposites. The functionalized MWCNT-ZnO nanocomposites showed significantly stronger photoinactivation of the bacteria than the... 

Vertical copper oxide nanoflakes were synthesized on a Cu foil through oxidation in alkaline conditions. X-ray photoelectron spectroscopy showed that after exposing the nanoflakes to an Escherichia coli bacterial suspension, the outermost surface of the nanoflakes was chemically reduced through the glycolysis process of the bacteria. Current-voltage (I-V) characteristics of the nanoflakes (measured perpendicular to surface of the Cu foil by using conductive atomic force microscopy) indicated that electrical resistivity of the nanoflakes increased about one order of magnitude after exposure to the bacterial suspension. The nanoflakes reduced by the bacterial suspension could also be... 

Various morphologies of CuO/Cu(OH)2 nanostructures with different adsorbed -OH contents were synthesized on an acid-treated Cu foil through variation of NaOH concentration from 0 to 50 mM with an in situ oxidation method. X-ray diffractometry and X-ray photoelectron spectroscopy (XPS) indicated formation of CuO on the Cu(OH)2 crystalline phase at a growth temperature of 60°C for 20 h. Antibacterial activity of the nanostructures against Escherichia coli bacteria was studied in the dark and under light irradiation. The nanostructures grown at a NaOH concentration of 30 mM showed the highest surface area and the strongest antibacterial activity among the samples. After elimination of the... 

For the first time, we report novel Ag3PO4/BiPO4 (AB)-graphene-based photocatalysts. The fabricated nanocomposites were characterized by various techniques. The photocatalytic properties of the prepared catalysts were evaluated by the photodegradation of Atrazine herbicide under both visible and UV light irradiation. Atrazine concentration was determined using the spectrophotometric method according to the Konig's reaction by monitoring the absorbance at 470 nm wavelength during the photodegradation process. Both degradation rate and efficiency using graphene (GR)-based nanocomposites are found to be much better than using pure AB. Atrazine photodegradation displayed that the AB supporting... 

While the photocatalytic degradation of various organic compounds under UV light irradiation has been widely investigated, visible-light-induced photocatalytic degradation of low levels of pollutants such as dibenzothiophene (DBT) is occasionally reported. In the present work, lanthanide/polyethylene glycol-modified TiO2 (La/PEG/TiO2) has been successfully synthesized by a sol-gel method. The photocatalyst was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-Vis diffusive reflectance spectroscopy, and energy dispersive X-ray analysis. Moreover, the photocatalytic degradation of DBT under visible light irradiation is...