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The comprehensive study of smoke deposited nano-sized MgO as a catalyst for biodiesel production was investigated. The transesterification reaction was studied under constant ultrasonic mixing for different parameters like catalyst quantity, methanol oil molar ratio, reaction temperature and reaction time. An excellent result of conversion was obtained at 1.5 wt% catalyst; 5:1 methanol oil molar ratio at 55 °C, a conversion of 98.7% was achieved after 45 min. The conversion was three to five times higher than those are reported for laboratory MgO in literature. This was mainly due to the enhancement of surface area of the catalyst and the activity of ultrasonic waves. Catalyst is easily recovered and reused up to eight times with easy regeneration steps. [ABSTRACT FROM AUTHOR]

Abstract: Highly ordered single crystalline nickel ferrite (NiFe2O4) nanorods have been successfully synthesized by a polymer assisted co-precipitation method using polyethylene oxide (PEO) as a capping and a polymer structure directing reagent. In this synthesis, the addition of high concentration of PEO seems to play an important role in the formation, size and shape control of the nanorods. Powder X-ray diffraction (XRD) and selected area electron diffraction (SAED) exhibit that the obtained nanorods can be indexed to single crystalline inverse spinel with Fd3m space group. The synthesized NiFe2O4 products were characterized in terms of their structural and magnetic properties. The morphological investigations using high resolution scanning electron microscopy (HRSEM) and transmission electron microscopy (TEM) reveal that the grown products are rod-like structure with the diameters in the range of 60–65nm and length of 142–147nm. The coercivity of prepared nanorods with high concentration of PEO reached as high as 904.46Oe at room temperature (300K), superior to that of nanoparticles obtained with low concentration of PEO. Hence, it can be used for high frequency electronics and gas sensing applications. On the basis of these experimental results, possible influence mechanisms in the growth processes are discussed. [Copyright &y& Elsevier]

Abstract: The leaf-like NiFe2O4 nanostructure formed from nanoparticles has been successfully prepared on polymer assisted sol–gel method. Here ethylene glycol (EG) is used as a gelling agent as well as solvent and PVA as a capping agent. A sequence of control experiments confirms that the polymer concentration with NiFe2O4 has direct influence on the morphology of the products. Characterization of the synthesized nanoparticles and nanoleaf are carried out using powder XRD, FT-IR, TGA, HR-SEM, TEM, HR-TEM, dielectric measurements tangent, microRaman and VSM. On the basis of these experimental results, potential influence mechanisms in the growth processes are proposed. [Copyright &y& Elsevier]

Abstract: Sheet-like nickel ferrite (NiFe2O4) has been synthesised with PVA matrices using co-precipitation technique. The sheet is formed from the oriented aggregation of single crystalline NiFe2O4 nanoparticles with PVA as the structure directing template. The synthesised materials are characterised based on X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), high-resolution scanning electron microscopy (HRSEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometry (VSM). The XRD results show that the nanocrystal contains single phase spinel structure of Fd3m space group. The existence of PVA with nanoparticles has been confirmed by FTIR spectra. The room temperature ferromagnetic property is exhibited by the as synthesised sample with high saturation magnetisation. [Copyright &y& Elsevier]

Abstract: Nickel ferrite (NiFe2O4) nanosheet has been synthesised by the polymer assisted co-precipitation method. The synthesised nanosheet was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), high-resolution scanning electron microscopy (HRSEM), thermal analysis and vibrating sample magnetometry (VSM). The results showed that the as synthesised NiFe2O4 has sheet like morphology with good crystalline nature. The nanosheet was formed through random aggregation of magnetic nanoparticles. Ferromagnetic property was exhibited by the nanosheet with saturation magnetization Ms =35emu/g, remanent Mr =8.6Oe and coercive force Hc =192emu/g. [ABSTRACT FROM AUTHOR]

Recently, bi-functional electrocatalytic materials have the potential for both the hydrogen evaluation reaction (HER) and oxygen evaluation reaction (OER) in the alkaline medium. In the present investigation, the cobalt sulfide/cobalt oxide hanged on the nitrogen-doped activated carbon nanosheets (CoS/CoO@NAC) as nanocomposites were synthesized through the hydrothermal and then the carbonization processes. The X-ray diffraction peaks observed in the CoS/CoO@NAC nanocomposites revealed the presence of CoS, CoO, and N-doped activated carbon nanosheets which confirmed the formation of binary nanocomposites. The BET analysis of CoS/CoO@NAC nanocomposites resulted an enhancement of the surface area of about 1038.57 m2/g along with the pore size and pore volume of 3.23 nm and 0.442 cc/g, respectively. The CoS/CoO@NAC, nanocomposites were used for bi-functional catalysis which divulged the low over potential for both HER and OER analyses at about −0.266 V and 0.199 V vs. RHE, respectively at 10 mA/cm2 current density in the alkaline medium. [Display omitted] • CoS/CoO@NAC nanocomposites synthesized by hydrothermal and carbonization processes. • CoS/CoO@NAC nanocomposites showed an enhancement of surface area of 1038.57 m2/g. • HER analysis of CoS/CoO@NAC shows an overpotential of −0.266 V. • OER analysis of CoS/CoO@NAC shows an overpotential of 0.2654 V. • CoS/CoO/NAC suitable for the bi-functional electrocatalyst in an alkaline medium. [ABSTRACT FROM AUTHOR]

Transition metal oxides with unique nanoarchitectures are being appraised as plausible candidates for the highly selective detection of contaminating organic gases due to their earth abundance, high surface area, and outstanding miniaturization potential. Here, two different nanoarchitectures of nickel molybdate (NMO), namely 3D-honeycombs (NMO-HCs) and 3D-rectangular nanosheets (NMO-RNS), are proposed and synthesized via a two-step wet-chemical process and characterized for their potential application in ethanol gas sensors. The successful formation of the different nanostructures and the even distribution of all the elements are demonstrated using various morphological and energy-dispersive X-ray spectroscopic (EDAX) analyses. In addition, N 2 -adsorption/desorption analysis is performed to confirm the highly porous nature and maximum surface areas of 30.4 m2 g−1 and 91.3 m2 g−1 at 77 K for the NMO-HCs and NMO-RNS, respectively. Furthermore, gas sensing analysis reveals that the NMO-HCs-based sensor provides a maximum gas response (R a /R g) of ~15.2 while the NMO-RNS-based sensor exhibits a 5.5 times higher maximum gas response of ~78.9 at the optimal operating temperature. Further, using R a /R g = 1.2 as the detection limit point, the lower limit of ethanol gas detection is found to be 0.2 ppm for the NMO-RNS-based device. Finally, the probable gas-sensing mechanism of the NMO-RNS is discussed. The present study indicates that the NMO-RNS sensor can sense ppb-levels of ethanol and is suitable for the monitoring of outdoor and indoor air quality in practical applications. Wet-chemical process assisted nickel molybdate (NMO) rectangular nanosheets were synthesized which demonstrates enhanced sensing performance towards ethanol. [Display omitted] • Nickel molybdate (NMO) nanosheets were prepared through wet-chemical process. • It exhibited 3D-hierarchical rectangular nanosheets morphology. • The NMO-RNS delivered the superior electrocatalytic activity. • The NMO-RNS achieved maximum gas response = 78.9. • The low detection limit of 0.2 ppm was achieved. [ABSTRACT FROM AUTHOR]