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The electroanalytical properties of Sn-decorated α-Fe2O3 nanoparticles have been synthesized by a facile co-precipitation method and the obtained nanoparticles were successfully used for determination of hydrazine. The structural and morphological of the as-prepared nanoparticles were employed using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) techniques. It was revealed from HR-TEM micrographs that tiny Sn nanoparticles grew well on the surface of α-Fe2O3 nanostructure. Optical property of the sample was characterized using UV–Vis spectroscopy. Electrocatalytic activities of Sn/α-Fe2O3 modified electrode was studied using cyclic voltammetry and amperometric measurements in 0.1 M PBS electrolyte towards N2H4 electro-oxidation. The limit of detection for the determination of N2H4 was found to be 10 nM. The modified electrode possessed sensitivities of 41.04 µA cm−2 mM−1 and 13.05 µA cm−2 mM−1 and wide linear ranges from 0.01 × 10−6 to 2.5 × 10−3 M with co-relation coefficient of R2 = 0.998 and R2 = 0.997, respectively. The Sn/α-Fe2O3 modified electrode also proves good reproducibility, long-term stability, selectivity and good antifouling properties. The Sn/α-Fe2O3 modified electrode sensor successfully demonstrated the practical applicability for detection of N2H4 in the real sample analysis. [ABSTRACT FROM AUTHOR]

A novel rhodamine-tryptamine conjugate-based fluorescent and chromogenic chemosensor (RTS) for detection of Hg2+ present in water was reported. After gradual addition of Hg2+ in aqueous methanol solution of RTS, a strong orange fluorescence and deep-pink coloration were observed. The probe showed high selectivity towards Hg2+ compared to other competitive metal ions. The 1:1 binding stoichiometry between RTS and Hg2+ was established by Job's plot analysis and mass spectroscopy. Initial studies showed that the synthesized probe RTS possessed fair non-toxicity and effectively passed through cell walls of model cell systems, viz., human neuroblastoma (SHSY5Y) cells and cervical cells (HeLa) to detect intercellular Hg2+ ions, signifying its utility in biological system. The limit of detection (LOD) was found to be 2.1 nM or 0.42 ppb by fluorescence titration. Additionally, the potential relevance of synthesized chemosensor for detecting Hg2+ ions in environmental water samples has been demonstrated.ᅟ [ABSTRACT FROM AUTHOR]

Abstract: An efficient and environmentally benign synthetic method has been developed for the library synthesis of biologically important multi‐functionalized isoindolo[2, 1‐a]quinazolines by two component domino condensation of 2‐carboxybenzaldehyde and 2‐aminobenzohydrazides/2‐aminobenzamides using graphene oxide (GO) as catalyst under solvent free conditions. The solvent‐free strategy exploiting inexpensive and eco‐compatible GO as mild carbocatalyst with large surface area is the major significant advantage of the present protocol. Furthermore, low catalyst loading, good to excellent yield of the products and easy recovery and recyclability of GO attribute considerable supremacy to the present protocol. [ABSTRACT FROM AUTHOR]

In this paper, we report a simple aqueous solution based chemical method for preparation of Cu nanoparticle loaded mesoporous silica SBA-15 (Cu@SBA-15) catalysts. Synthesized catalysts were characterized by powder X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscope (HRTEM), N 2 adsorption–desorption surface area and pore size analyzer, and particle size analyzer. Catalytic activity of Cu nanoparticle loaded SBA-15 towards reduction of various dyes, such as 4-nitrophenol, Methyl Orange, Congo Red, Rhodamine B, Methylene Blue and mixture of dyes were investigated in the presence of excess NaBH 4 . Catalysis reactions were monitored by employing UV–vis spectroscopy. Catalysis reactions followed pseudo-first order rate equation. These catalysts exhibited excellent catalytic activity and convenient recycling. The high catalytic activity, cost effectiveness and simple preparation methodology make 12.5Cu@SBA-15 an attractive catalyst for decolorization of organic dyes. [ABSTRACT FROM AUTHOR]

In this paper, we report a simple but novel aqueous solution based ‘one-pot’ method for preparation of (Ni 0.65 Zn 0.35 Fe 2 O 4 ) x –(BaFe 12 O 19 ) 1 − x nanocomposites consisting of hard ferrite–soft ferrite phases. Nanocomposites, having same compositions, have also been prepared by employing a physical mixing method. X-ray diffraction analysis showed the presence of nanocrystalline Ni 0.65 Zn 0.35 Fe 2 O 4 and BaFe 12 O 19 phases in the composites, prepared by both methods. However, transmission electron microscopic and scanning electron microscopic analysis revealed that, nanocomposites, prepared by one-pot method, possessed better homogeneous intimacy of Ni 0.65 Zn 0.35 Fe 2 O 4 and BaFe 12 O 19 phases than that of the nanocomposites, prepared by physical mixing method. Nanocomposites, prepared by one-pot method, have shown magnetically single phase behaviour with good spring exchange coupling interaction between hard and soft ferrite phases. These composites possessed enhanced magnetic properties with high saturation magnetization as well as high coercivity. These nanocomposites also exhibited very good microwave absorption properties in the X-band region. Composite having composition (Ni 0.65 Zn 0.35 Fe 2 O 4 ) 0.85 –(BaFe 12 O 19 ) 0.15 showed the minimum reflection loss of ~− 21 dB (> 99% absorption) at 9.86 GHz for absorber thickness of 3.05 mm. Magnetic and microwave absorption properties of the nanocomposites, prepared by one-pot method, were found be superior to those of the nanocomposites prepared by physical mixing method as well as pure Ni 0.65 Zn 0.35 Fe 2 O 4 and BaFe 12 O 19 nanoparticles. [ABSTRACT FROM AUTHOR]

Single-phase cobalt ferrite (CoFe2O4) nanopowder, with average particle size ∼20 nm, has been synthesised using an ethylene diamine tetra acetic acid precursor-based method. CoFe2O4nanopowder was obtained by calcining precursor at 550°C for 4 h in air. The change of microstructure of the synthesised CoFe2O4with increasing sintering temperature was studied using scanning electron microscopy. DC electrical resistivities of unsintered and sintered samples were measured using a two-probe method. Room temperature magnetic hysteresis measurement revealed that the synthesised CoFe2O4nanopowder exhibited ferromagnetic behaviour at room temperature with saturation magnetisation of 67.55 emu/g and coercivity of 1645.24 Oe. [ABSTRACT FROM PUBLISHER]

A novel 'one-pot' synthetic method has been reported for the preparation of (NiFe2O4)x-(BaFe12O19)1−x composites. The synthesized composites were characterized using thermogravimetric analysis, differential scanning calorimetric analysis, X-ray diffraction, dynamic light scattering technique, scanning electron microscopy, and vibrating sample magnetometer. The (NiFe2O4)x-(BaFe12O19)1−x composites prepared by this method showed crystallographically two phase behavior, but magnetically a good single phase exchange spring-coupled behavior with high saturation magnetization as well as high coercivity. [ABSTRACT FROM AUTHOR]

An ethylenediamine tetraacetic acid (EDTA) precursor-based chemical method has been reported for preparation of single-phase barium hexaferrite nanopowder. Synthesized powders were characterized by thermogravimetric analysis, differential scanning calorimetric analysis, x-ray diffraction, particle size analysis, transmission electron microscopy, and scanning electron microscopy. DC electrical resistivity and magnetic properties of synthesized BaFe12O19 were measured by using a two-probe method and a vibrating sample magnetometer, respectively. This EDTA precursor-based method has the capability of producing nanostructured pure single-phase BaFe12O19 powder at a comparatively lower calcination temperature and offers the potential of a simpler, more cost-effective route than other reported methods. [ABSTRACT FROM AUTHOR]

A magnetically separable core–shell CoFe2O4@SiO2‐SO3H nanocatalyst has been successfully exploited as a heterogeneous acid catalyst in the synthesis of diversely substituted biologically important spiro fused pyrrolo/indolo[1,2‐a]quinoxaline derivatives through the condensation of N‐(2‐aminophenyl)pyrroles/indoles and various cyclic conjugated 1,2‐diones in ethanol under ultrasonic irradiation. Room temperature synthesis, short reaction time, wide substrate scope, good to excellent yield of products and use of a magnetically separable and recyclable nanocatalyst make this method attractive and practicable. A magnetically separable CoFe2O4@SiO2‐SO3H nanocatalyst having core–shell morphology has been employed for the very first time in a benign strategy to synthesize a series of novel spiro fused quinoxaline derivatives under ultrasonic irradiation. Spiro fused quinoxaline derivatives derived from acenaphthoquinone, 9,10‐phenanthroquinone and [1,2]benzoquinone are reported. Room temperature synthesis, shorter reaction time, wide substrate scope, good to excellent yield and use of a magnetically separable and recyclable nanocatalyst make this synthetic protocol attractive. [ABSTRACT FROM AUTHOR]

[Display omitted] • Industrial scale adopted chemical method used for preparation of Sn doped CeO 2. • Sn-CeO 2 /GCE electrode demonstrated as an excellent electrocatalytic oxidation of nitrite (NO 2 –) • The remarkable sensitivities of nitrite found that 245.4 µA cm−2 mM−1 and 89.53 µA cm−2 mM−1. • The limit of detection (LOD) towards nitrite ion sensing was found to be 16 nM. Development of novel electrode materials for sensing water pollutant like nitrite, nitrate, paramedical pollutants and fertilizers is a more promising research area in electrochemical sensor field. Various pure as well as doped metal oxides were used as electrodes for sensing the water pollutants but, deficits in stability, reproducibility and real time analysis. In the present work, a promising Sn-doped CeO 2 based sensor was fabricated for sensing nitrite in water. A selective concentration of Sn (5%) doped CeO 2 nanoparticles were synthesized by facile chemical precipitation method. The structural, optical and morphological information were studied using various techniques. The morphological of the sample was revealed an agglomerated with spherical nanoparticles with size of 8.5 nm. The synergistic effect of Sn-CeO 2 /GCE improves the electrochemical behavior of nitrite on the modified surface. Sn-doped CeO 2 nanoparticles has a better surface property and provides a more fine-grained media to facilitate electron transfer during the reaction between analyte and electrode. The Sn-CeO 2 /GCE electrode possesses excellent electrocatalytic oxidation of nitrite (NO 2 –) which was investigated by cyclic voltammetry (CV) and amperometry techniques. The remarkable sensitivities of nitrite were found that 245.4 µA cm−2 mM−1 and 89.53 µA cm−2 mM−1 with R2 = 0.999 and RSD of ∼ 6%. Similarly, the limit of detection (LOD) towards nitrite ion sensing was found to be 16 nM. The real time application of Sn-CeO 2 /GCE sensor was demonstrated by the detection of nitrite present in environmental water samples with excellent recoveries. Hence, Sn-doped CeO 2 modified electrode also demonstrates good reproducibility, long time stability, and excellent selectivity properties. Thus, a developed electrochemical sensor possesses a novel promise for the construction of simple and sensitive nitrite analytical stage. [ABSTRACT FROM AUTHOR]

Here we report the development of a glucose sensor based on electrochemical detection. The working electrode was a screen printed Au electrode, which was modified with Ru nanoparticle loaded thiol functionalized mesoporous silica. This sensor demonstrated its capability of detecting and estimating glucose concentration in aqueous medium over a wide range of concentration with high sensitivity, durability and reproducibility.

Here we report the synthesis of TiO2 nanoparticle loaded mesoporous MCM-41 photocatalysts for degradation of methyl orange dye in aqueous medium under sunlight exposure. TiO2 loaded MCM-41 was synthesized by impregnation method. Anatase form of TiO2 nanoparticles were formed in the porous matrix of the silicate MCM-41. The synthesized materials were characterized using powder X-ray diffraction method, surface area and porosimetry analysis; diffuse reflectance analysis, particle size analysis and transmission electron microscopy. The photocatalytic property of the synthesized materials were investigated towards the degradation of methyl orange under sunlight exposure and monitored by UV-visible spectrophotometer. Synthesized catalysts showed high photocatalytic activity for the degradation of methyl orange.

In this paper, we report a simple aqueous solution based chemical method for preparation Ru nanocatalysts supported on mesoporous silica SBA-15 (Ru@SBA-15) catalysts. Synthesized catalysts were characterized by powder X-ray diffraction (XRD), Optical emission spectroscopy (ICP-OES), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscope (HRTEM) and N2 adsorption-desorption surface area and pore size analyzer, and particle size analyzer. Catalytic activity of the synthesized catalysts towards decolorization of various dyes, such as 4-nitrophenol, Methyl Orange, Congo Red, Rhodamine B, Methylene Blue and mixture of dyes was investigated in presence of excess NaBH4. Catalysis reactions were monitored by employing UV-vis spectroscopy. Catalysis reactions followed pseudo-first order rate equation. The catalyst with 2.5 wt% Ru nanoparticle exhibited excellent catalytic activity and convenient recycling. The high catalytic activity and simple preparation methodology make 2.5Ru@SBA-15 an attractive catalyst for decolorization of organic dyes.

In this paper, we report a simple but novel aqueous solution based 'one-pot' method for preparation of (NiFe2O4)x-(SrFe12O19)1-x nanocomposites consist of hard ferrite-soft ferrite phases. A physical mixing method has also been employed to prepare nanocomposites having same compositions. The effects of synthetic methodologies on the microstructures of the nanocomposites as well as their magnetic and microwave absorption properties have been evaluated. Crystal structures and microstructures of these composites have been investigated by using X-ray diffraction, transmission electron microscope and scanning electron microscope. In the nanocomposites, prepared by both methods, presence of nanocrystalline NiFe2O4 and SrFe12O19 phases was detected. However, nanocomposites, prepared by one-pot method, possessed better homogeneous distribution of hard and soft ferrite phases than the nanocomposites, prepared by physical mixing method. Nanocomposites, prepared by one-pot method, demonstrated significant spring exchange coupling interaction between hard and soft ferrite phases and exhibited magnetically single phase behaviour. The spring exchange coupling interaction enhanced the magnetic properties (high saturation magnetization and coercivity) and microwave absorption properties of the nanocomposites, prepared by one-pot method, in comparison with the nanocomposites prepared by physical mixing method as well as pure NiFe2O4 and SrFe12O19 nanoparticles. Minimum reflection loss of the composite was ~ -17 dB (i.e., 98% absorption) at 8.2 GHz for an absorber thickness of 3.2 mm.