Vietnam Journal of Catalysis and Adsorption

The experiment had fabricated and studied the properties of ZnO and Cu doped ZnO nanoparticles with the change of the hexamethylene tetramine surfactant content (HMTA) with molar ratio Zn2 +: HMTA = 1: x; x = 1, 2 and 4. The methods were used to study the characteristics of materials such as: XRD, raman shift, SEM, reflection spectrum. The results show that, when the content of surfactant HMTA increased (1-4 mol versus the moles of Zn2+), the size of the nanorods crystals of fabricated materials had reduced from 64.5 to 21.7 nm. The reflectance spectrum of Cu doped ZnO materials samples was lower in the visible light region compared to pure ZnO samples. The photocatalytic properties for decomposition of methylene blue organic dye of the Cu doped ZnO sample (with the greatest concentration of HMTA surfactant of 4 mol versus the moles of Zn2+) reached 98% after 40 minutes of ultraviolet light irradiation, with the rate constant k= 0,13261 min-1. 

These experiment fabricated C3N4 powdermaterials by the calcinational method and fabricated Cu2O, Cu2O-3%C3N4, Cu2O-5%C3N4 nanomaterials by the hydrothermal method. The powdermaterials characteristics were studied by methods such as: X-ray diffraction (XRD); raman shift; scanning electron microscope (SEM); UV-vis solid absorption spectra. The photocatalytic activity of samples was studied by decomposition of methylene blue dye under visible light radiation. The results showed that the fabricated C3N4 sample was single phase with high porosity cotton structure. The Cu2O, Cu2O-3%C3N4 and Cu2O-5%C3N4 samples had octahedral crystal structure with the crystal particle size was about 200-300 nm. The C3N4 doped Cu2O samples had octahedral crystal particles arranged more closely than that of Cu2O and filled in gaps by cotton, porous clusters of C3N4. The materials all had the absorption spectra expanded in the visible light region (l» 450-900 nm). The C3N4 doped Cu2O samples achieved the better photocatalytic efficiency than Cu2O and C3N4 samples in visible light region. The highest photocatalytic efficiency achieved 100% was of the Cu2O-3%C3N4 sample in the photodegradation of methylene blue dye after 30 minutes under visible light irradiation.  

In this study, silver-copper complex/chitosan (Ag-Cu@CS) nanoparticles were successfully synthesized by in-situ encapsulation reduction method. The results show that as-synthesized nanoparticles were quasi spherical in shape with the average diameter of 7.97 nm, well-dispersed particles in water and stable. The test phytopathogenic fungi Sclerotium rolfsii, Magnaporthe oryzae K, Botrytis cinerea, and Colletotrichum gloeospodises were isolated from diseased fruits of Vinh orange trees, which was cultivated in Nghe An province. The obtained Ag-Cu@CS product have strong inhibition agaisnt four fungi in-vitro. The inhibitory effect of silver-copper complex/chitosan (Ag-Cu@CS) nanoparticles at concentrations of 25 ppm was reached over 50% on Sclerotium rolfsii, Magnaporthe oryzae, and Botrytis cinerea at a concentration of 50 ppm, the inhibitory effect of the nanoparticles on Colletotrichum gloeospodises reached over 50% after 4 days of culture. These results suggested that silver-copper complex/chitosan (Ag-Cu@CS) nanoparticles can be used as a promising fungicide for plant protection.

The Mo-modified TiO2 was synthesized via facile impregnation combined with pyrolysis of mixtures in several different initial mass ratios of precursors as mTi(OH)4/m(NH4)6Mo7O24.4H2O equaling 5, 10 and 15 in 500 oC for an hour. The as-prepared samples, denoted as n-MT-500 within n for the initial mass ratio of precursors, were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, Raman spectroscopy, as well as X-ray photoelectron spectroscopy, which all not only illustrate the presence of TiO2 and MoO3 components in the composites but also demonstrate the introduction of Mo hetero-atom into anatase lattice. All of the obtained samples performed higher photocatalytic activity under visible light than TiO2 via the photodecomposition of RhB in aqueous solution, in which 10-MT-500 exhibits the highest degradation efficiency up to 87% after 5-hour illumination.

The experiment had fabricated and studied the properties of ZnO and Cu doped ZnO nanoparticles with the change of the hexamethylene tetramine surfactant content (HMTA) with molar ratio Zn 2 + : HMTA = 1: x; x = 1, 2 and 4. The methods were used to study the characteristics of materials such as: XRD, raman shift, SEM, reflection spectrum. The results show that, when the content of surfactant HMTA increased (1-4 mol versus the moles of Zn 2+ ), the size of the nanorods crystals of fabricated materials had reduced from 64.5 to 21.7 nm. The reflectance spectrum of Cu doped ZnO materials samples was lower in the visible light region compared to pure ZnO samples. The photocatalytic properties for decomposition of methylene blue organic dye of the Cu doped ZnO sample (with the greatest concentration of HMTA surfactant of 4 mol versus the moles of Zn 2+ ) reached 98% after 40 minutes of ultraviolet light irradiation, with the rate constant k= 0,13261 min -1 .

Titanium oxides nanotubes (TNTs) were prepared by hydrothermal method and used as nano-support for nickel nanoparticles. Indeed, nickel nanoparticles supported TNTs (Ni-TNTs) were in situ synthesized from nickel salt and TNTs by chemical reduction method using sodium borohydride (NaBH4) as reducing agent. The physio-chemical properties of Ni-TNTs nano-catalysts were fully characterized such as Transmission Electron Microscopy (TEM), Scanning Electron Microscope (SEM), and X-ray diffraction (XRD). The results showed that nickel salt was completely reduced to Ni0 metal with an average particle size of 12 nm. On the other hand, the catalytic activity is tested by the hydrodechlorination of chlorinated organic compounds. The hydrode-chlorinated conversion of 3-chlorophenol was obtained over 97%.

Nanoflower MoS2, nanowire TiO2(NNW) and 3D MoS2/TiO2 nano-heterostructure have been synthesized successfully by simple typical hydrothermal reaction method followed by 200oC calcination under an argon atmosphere. The prepared samples are characterized in detail by XRD, FESEM, UV-vis DRS, EDX and BET. The results suggest that the TiO2 NNW is successfully coupled with MoS2 to form the heterojunction nanostructure. The hybrid heterostructures can effectively utilize visible-light and solar energy to degrade 2,4-dichlorophenoxyacetic acid (2,4-D). The degradation rate of 2,4-D is as high as 99%. The improved photocatalytic activity owes to the decreased band-gap and the heterosurface properties of MoS2/TiO2, promoting the electron-hole pairs separation and absorption capacity to visible light. This work presents a facile approach for fabricating the MoS2/TiO2 heterostructures for efficient photocatalytic 2,4-D solution, which will facilitate the development of designing photo catalysts applied in environment and energy.

Undoped and Fe-doped ZnO nanosheets have been successfully synthesized by hydrothermal method using zinc acetate as the source of  Zn2+, iron(III) nitrate as the doping source, urea as media to control the solution pH and polyethylene glycol as structure-directing agents. The obtained materials were characterized by means of XRD, TEM, BET, FT-IR and UV-Vis-DRS. The results show that ZnO has a hexagonal wurtzite structure and that the Fe3+ ions were well incorporated into the ZnO nanosheets crystal lattice. As the Fe/Zn molar ratios increased from 0.05% to 0.1% results in increased absorption in the visible region of the spectrum, a slightly decreased optical band gap and increased photocatalytic activity in comparison with the undoped ZnO. The photocatalytic activity was evaluated based on photodegradation of methylene blue (MB) in aqueous solutions under visible light irradiation. The optimum Fe doping at the molar ratios of Fe/Zn = 0.1% showed the highest photocatalytic activity and was 2.19 times higher than that of undoped ZnO. The kinetic studies showed the decomposition of MB followed pseudo first-order kinetics with the rate constant were determined kapp = 7.33×10-2 min−1.

An efficient and practical method for the synthesis of pyrroles by Cu-catalyzed multicomponent reaction has been described. A range of highly functionalized pyrroles was prepared in good yields under solvent free condition.

In this study, the g-C3N4/CoFe2O4/Reduced graphene oxide composites were successfully synthesized by the co-precipitation method combined with mixed phase mixture. The obtained results from characterization methods such as XRD, SEM, FT-IR, EDX,… showed that the composite has a high structure and crystallinity, and spinel ferrite particles were dispersed fairly evenly onto reduced graphene oxide sheets as well as layers of g-C3N4. The existence of Co/Fe-O and Co-O-C bonds in materials was determined. The photocatalytic activity of g-C3N4/CoFe2O4/Reduced graphene oxide (GCN/CF-rGO) was estimated through the degradation of Tetracycline (TC) in aqueous solution. TC decomposition efficiency is up to 95% after 240 minutes of reaction and is higher than that of each component material. GCN/CF-rGO is a potential catalyst for effective application in TC decomposition reaction under visible light and has the ability to implement treatment in practice.