Igor Djerdj

Surfactant-assisted synthesis of CeO2 nanoparticles and their application in wastewater treatment

The stable and crystalline phase of pure nanostructured CeO2 with various morphologies has been directly synthesized using a cationic surfactant (cetyltrimethylammonium bromide, CTAB) and cerium chloride (CeCl3·6H2O) at room temperature by a new, simple, and green chemical precipitation method. Thorough structural characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction, and Raman spectroscopy, were employed to examine the morphology and the microstructure of the final product. The catalytic activity of the nanostructured CeO2 was tested towards the degradation of the azo dye Congo red (CR). In order to obtain the optimum degradation conditions of CR, the performance of nanostructured CeO2 with various morphologies (spherical nanoparticles, nanorods, and mixture thereof) for the removal of CR from wastewater was tested under various concentrations of CR dye and quantities of the nanostructured CeO2. The results show an excellent removal capacity for the organic pollutant CR from wastewater, making it a promising candidate for wastewater treatment.

Nanocrystalline NiMoO4 with an ordered mesoporous morphology as potential material for rechargeable thin film lithium batteries

Nanocrystalline nickel molybdate (NiMoO(4)) thin film electrodes with a 3D honeycomb structure of uniform 17 nm diameter pores were successfully produced through facile polymer templating strategies. These novel sol-gel type materials exhibit enhanced lithium ion storage capabilities, and thus show promise for battery applications.

Efficient microwave-assisted synthesis of LiFePO4 mesocrystals with high cycling stability

Lithium iron phosphate mesocrystals with high cycling stability were directly synthesized within a few minutes under ambient pressure conditions using a microwave-directed nonaqueous liquid phase synthesis approach.

Diluted magnetic semiconductors: Mn/Co-doped ZnO nanorods as case study

The structure and the magnetic properties of 3 and 5 mol% (based on the starting concentrations) Co- and Mn-doped ZnO nanorods, synthesized by a straightforward and experimentally simple nonaqueous sol–gel route based on benzyl alcohol as solvent, have been investigated by various characterization techniques, including X-ray diffraction with Rietveld refinement, high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy, magnetization measurements and electron paramagnetic resonance. The doped as-synthesized ZnO nanocrystals retain the wurtzite structure with a morphology in the form of nanorods grown along the [001] direction, whose dimensional parameters as well as degree of agglomeration depend on the type and level of doping. The Co-doped ZnO powders are ferromagnetic with a Curie temperature exceeding room temperature. Conversely, the Mn-doped samples show antiferromagnetic correlations with a possible transition to an antiferromagnetic ground state below TN = 10 K. The results suggest that the magnetic ground state is extremely sensitive to the type of dopant, which is in agreement with previous studies.

Soft-templating synthesis of mesoporous magnetic CuFe2O4 thin films with ordered 3D honeycomb structure and partially inverted nanocrystalline spinel domains

Combining sol-gel chemistry with polymer templating strategies enables production of CuFe(2)O(4) thin films with both an ordered cubic network of 17 nm diameter pores and tunable spinel domain sizes. These nanocrystalline materials contain only minor structural defects with λ = 0.85 ± 0.02 and exhibit multiple functionalities, including superparamagnetic behavior (T(B)≈ 310 K) and redox- and photoactivity.

Combustion synthesis of porous Pt-functionalized SnO2 sheets for isopropanol gas detection with a significant enhancement in response

Pt-functionalized SnO2 sheets with Pt contents of 0, 0.5, 1, and 2 wt% were synthesized by a facile solution combustion synthesis, and their crystal structure, morphology, and chemistry have been thoroughly characterized. In the combustion process, the urea (CO(NH2)2) has been employed as a fuel. The obtained products appear as porous sheets formed by the interconnected and loosely packed SnO2 nanoparticles. Pt nanoparticles are assembled together with SnO2 nanoparticles in several up to tens of nanometer clusters. The as-synthesized products were used as sensing materials in the sensors to detect the isopropanol (IPA) gas. Gas sensing tests exhibited that the Pt-functionalized SnO2 are highly promising for gas sensor applications, as the operating temperature was lower than current IPA sensors and the response to IPA was significantly enhanced. The 2 wt% Pt–SnO2 sheet based gas sensor displayed a response value of 190.50 for 100 ppm IPA at an optimized operating temperature of 220 °C, whereas the pristine SnO2 based gas sensor only showed a response of 21.53 under the same conditions. The roles of Pt nanoparticles on electronic sensitization of SnO2, catalytic oxidation (spillover effect), and the increased quantities of oxygen species on the surface of SnO2 are plausible reasons to explain the significant enhancement in response to a Pt-functionalized SnO2 sheet based gas sensor.

Solvothermal and surfactant-free synthesis of crystalline Nb2O5, Ta2O5, HfO2, and Co-doped HfO2 nanoparticles

A simple route to niobium, hafnium and tantalum oxide nanocrystals using a nonaqueous sol-gel route based on the solvothermal reaction of the corresponding metal chlorides with benzyl alcohol is presented. This approach can easily be extended to the preparation of high quality Co-doped HfO(2) nanoparticles of uniform size and shape and with a homogenous distribution of the magnetic ions. The structural characterization of all these nanomaterials as well as the magnetic properties of pure and doped hafnia, with special attention to the doping efficiency, are discussed. The obtained Co-doped hafnia exhibits paramagnetic properties with very weak antiferromagnetic interactions between Co ions moments.

Porous NiO nanosheets self-grown on alumina tube using a novel flash synthesis and their gas sensing properties

Porous NiO nanosheets were self-grown on an alumina tube with a pair of Au electrodes connected by platinum wires via a simple solution combustion synthesis. A cubic NiO phase was obtained by a mixed solution of an oxidizer of nickel nitrate and a fuel of ethylene glycol (EG) at 400 °C. The phases and the morphologies of the materials self-grown on an alumina tube were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that the alumina tube was entirely covered by NiO nanosheets with several micrometers in thickness. The NiO nanosheets on the surface of the tube were assembled by a large number of nanoparticles of irregular shapes and pores with different sizes. The electronic and gas-sensing characteristics of the self-grown porous NiO nanosheets for volatile organic compound (VOC) vapours (ethanol, acetone, methanol, and formaldehyde) were investigated. The resistance of the sensor directly based on the self-grown NiO dramatically drops from 100–240 °C, and then slightly decreases with further increasing temperature to about 28 kΩ at 400 °C. The sensor based on the self-grown NiO exhibits low detection limit, fast response and recovery and wide dynamic range detection to VOC vapours, especially ethanol, at the respectively optimal operating temperatures.

Nonaqueous Synthesis of Colloidal ZnGa2O4 Nanocrystals and Their Photoluminescence Properties

In conclusion, we have presented the non-aqueous synthesis of crystalline ZnGa2O4 nanocrystals with a mean size of about 7 nm and with a narrow particle size distribution. The nanocrystals can easily be dispersed in chloroform to form stable colloids without the use of any additional stabilizers. Strong blue fluorescence was observed from the clear colloidal solution of the nanocrystals under UV light. These observations point to a potential use of the particles as a new class of fluorescent biomarkers which are more stable and more biologically benign than the currently employed Cd- derivatives.

A high-performance n-butanol gas sensor based on ZnO nanoparticles synthesized by a low-temperature solvothermal route

ZnO nanoparticles with high crystallinity and several nanometers in size were synthesized by a low-temperature solvothermal route from zinc acetate dihydrate (Zn(CH3COO)2·2H2O), potassium hydroxide (KOH) and methanol (CH3OH). The structural and the morphological characterizations of the ZnO nanoparticles were performed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2-sorption isotherms. The obtained nanoparticles are highly crystalline wurtzite-type ZnO with a uniform near-spherical shape and an average particle size estimated to be 8.4 ± 1.3 nm. Such a small particle size and slight agglomeration are attributed to the use of methanol, which acts as both a solvent and an inhibitor of growth and agglomeration. The as-synthesized ZnO nanoparticles were directly used as a gas sensing material toward n-butanol gas. Such a designed sensor device exhibits several advantages such as a high and fast response, short recovery time, and good stability toward n-butanol gas. At the optimal operating temperature (320 °C), its gas response toward 500 ppm n-butanol is 805 and the response and recovery times are 22 and 6 seconds, respectively.