R. Manigandan

Fabrication of Ni–Fe2O3 magnetic nanorods and application to the detection of uric acid

Doping of Ni into Fe2O3 lattices has been achieved by co-precipitation followed by thermal decomposition method. The structural, morphological, and magnetic properties of the fabricated samples were investigated by X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FT-IR) spectroscopy, UV-visible absorption (UV-vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The results reveal that the Ni is well doped within the lattices of Fe2O3. The Ni dopant suppresses the formation of more stable α-Fe2O3 at higher calcination temperature. Further, the Ni-doped Fe2O3 nanoparticles were used to fabricate an electrochemical sensor (Ni–Fe2O3/GCE) for the detection of uric acid (UA) in biological conditions by cyclic voltammetry (CV) and chronoamperometry (CA). It was found that 5%Ni–Fe2O3/GCE exhibits best response towards UA with less positive potential and larger current response. Furthermore, the sensor gives good linear current response in the concentration range of 6.6 to 112.4 μM with the higher sensitivity of 0.849 μA (μM cm2)−1. Such fabricated sensors are appropriate for newly emerging non-enzymatic electrochemical nanobiosensors.

Synthesis and characterization of chromium(III) Schiff base complexes: Antimicrobial activity and its electrocatalytic sensing ability of catechol

A series of acyclic Schiff base chromium(III) complexes were synthesized with the aid of microwave irradiation method. The complexes were characterized on the basis of elemental analysis, spectral analysis such as UV-Visible, Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) spectroscopies and electrospray ionization (ESI) mass spectrometry. Electrochemical analysis of the complexes indicates the presence of chromium ion in +3 oxidation state. Cr (III) ion is stabilized by the tetradentate Schiff base ligand through its nitrogen and phenolic oxygen. From the spectral studies it is understood that the synthesized chromium(III) complexes exhibits octahedral geometry. Antimicrobial activity of chromium complexes was investigated towards the Gram positive and Gram negative bacteria. In the present work, an attempt was made to fabricate a new kind of modified electrode based on chromium Schiff base complexes for the detection of catechol at nanomolar level.

Synthesis, growth and photoluminescence behaviour of Gd2O2SO4:Eu3+ nanophosphors: the effect of temperature on the structural, morphological and optical properties

Gd2(SO4)3·8H2O, Gd2O2SO4, and Gd2O2SO4:Eu3+ nanoparticles have been synthesized in the presence of Gd3+ ions and sodium dodecyl sulphate (SDS) by the simple complexation-thermal decomposition (CTD) method. The structural analysis, growth mechanism and optical properties of the Gd2(SO4)3·8H2O, and Gd2O2SO4 are described by the diffraction pattern, functional group analysis, Raman, morphology, elemental analysis, and absorbance spectra. The most intriguing factor was that the Gd2O2SO4 nanoplates are in the range of 42–50 nm without adding any external stabilizer. The results revealed that the Gd2O2SO4 nanoparticles with an orthorhombic structure have a band gap of 3.12 eV. Furthermore, Gd2O2SO4 shows an intense red photoluminescence associated with the 5D0 → 7F2 transition in the presence of Eu3+. The results suggest that the Gd2O2SO4:Eu3+ nanophosphors, may have a beneficial approach in the field of biomedical application as luminescent probe/labels.

Manganese sesquioxide to trimanganese tetroxide hierarchical hollow nanostructures: effect of gadolinium on structural, thermal, optical and magnetic properties

Various hollow manganese oxide (bixbyite Mn2O3 and hausmannite Mn3O4) nanoparticles (NPs) with different morphologies were obtained from a single precursor, manganese oxalate (MnC2O4). To synthesize a Mn3O4 stacked nanostructure rather than coral-like Mn2O3 nanospheres, as synthesized MnC2O4 was thermally decomposed at 700 °C in the presence of Gd3+, through the oriented arrangement mechanism. The formation process and structural variation arising from varying the thermal treatment (450 °C and 700 °C) and the cationic dopant Gd3+ were analyzed by FTIR, TGA, and XRD. The unexpected size reduction, and significant physicochemical properties were analyzed using various techniques such as FESEM coupled with EDAX, HR-TEM, DRS-UV-vis, EPR, EIS and VSM. The addition of gadolinium induces particle size reduction and a phase transition from cubic Mn2O3 to tetragonal Mn3O4, which leads to the suppression of the electrical conductivity, and changes in the optical band gap. The prepared Mn3O4 nanocrystals exhibit ferromagnetic behavior below Tc ≈ 45 K and weak paramagnetic behavior at room temperature.

Copper vanadate nanoparticles: synthesis, characterization and its electrochemical sensing property

Copper vanadate (Cu2V2O7) nanoparticles were synthesized by a simple thermal decomposition method. The synthesized copper vanadate nanorods were characterized by X-ray diffraction analysis, and it is found that the synthesized sample belongs to monoclinic Cu2V2O7. Fourier transform infrared spectroscopy (FT-IR) confirms the formation of Cu–O bond in the sample. Ultraviolet–visible (DRS-UV–visible) spectroscopy and photoluminescence spectroscopy reveals the optical property of the Cu2V2O7 nanoparticles. The nanobar-like morphology was confirmed by both scanning electron microscopy and high resolution transmission electron microscopy. Further, the electrochemical sensing behavior of Cu2V2O7 nanoparticles was investigated by cyclic voltammetry using lidocaine as an analyte. The electrochemical sensing experiment suggests that the Cu2V2O7 nanoparticles will become a potential candidate in the field of drug sensor.

Facile solvothermal decomposition synthesis of single phase ZnBi38O60 nanobundles for sensitive detection of 4-nitrophenol

We have developed the facile solvothermal decomposition route to fabricate a single phase zinc bismuthate (ZnBi38O60) binary composite nanostructure. Interestingly, the proposed technique provides a new pathway to synthesize similar multi compound oxide materials. The prepared ZnBi38O60 was characterized by different analytical techniques. Typical crystalline phase and chemical composition were confirmed using X-ray diffraction (XRD) and X-ray photoelectron spectra. Unique nanobundle morphology of the ZnBi38O60 was confirmed by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). A glassy carbon electrode modified using ZnBi38O60 nanobundles as the electrocatalyst was used to qualitatively and quantitatively determine 4-nitrophenol (4-NP) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The modified electrode exhibits better sensitivity (1.024 μA μM−1 cm−2) and limit of detection (LOD) 35 × 10−9 M. Thereby it can be concluded that ZnBi38O60 nanobundles could be another choice of electrocatalyst for 4-NP determination and can be extended to various nitro containing analytes.

Polyaniline Nanorods: Synthesis, Characterization, and Application for the Determination of para-Nitrophenol

ABSTRACT A para-nitrophenol sensor based on a 5-sulfosalicylic acid doped polyaniline nanorods modified glassy carbon electrode is reported. The formation of 5-sulfosalicylic acid doped polyaniline was characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electroactivity of the 5-sulfosalicylic acid doped polyaniline nanorods was studied by cyclic voltammetry and differential pulse voltammetry and high response was observed for the reduction of para-nitrophenol. The calibration curve for para-nitrophenol was linear from 6.7 × 10−6 M to 112.1 × 10−6 M. The sensitivity and limit of detection were 24 nA µM−1 and 3.2 × 10−6 M, respectively. The sensor was simple, inexpensive, and employed for the determination of para-nitrophenol in tap water with recoveries from 97.6 to 101.0%.

Characterization of Mo-MCM-41 and its Electrochemical Sensing Property

By direct hydrothermal method, Mo-MCM-41 mesoporous catalysts with different Si/Mo ratio were prepared. Mo-MCM-41 was characterized by XRD, FT-IR, and DRS UV-Vis spectroscopy. The morphological property of the samples was characterized by SEM. The SEM images show the agglomeration of the particles. The synthesized Mo-MCM-41 was used to modify glassy carbon electrode (Mo-MCM-41/GCE). The detection of 4-chlorophenol (4-CP) using Mo-MCM-41/GCE in a pH 7.4 phosphate buffer solution (PBS) was carried out by cyclic voltammetry (CV). At the Mo-MCM-41/GCE, 4-CP is oxidized at less positive potential with larger current response than the bare GCE.

Synthesis, characterization, optical and sensing property of manganese oxide nanoparticles

Manganese oxide nanoparticles were prepared by thermal decomposition of manganese oxalate. Manganese oxalate was synthesized by reacting 1:1 mole ratio of manganese acetate and ammonium oxalate along with sodium dodecyl sulfate (SDS). The structural characterization of manganese oxalate and manganese oxide nanoparticles was analyzed by XRD. The XRD spectrum confirms the crystal structure of the manganese oxide and manganese oxalate. In addition, the average grain size, lattice parameter values were also calculated using XRD spectrum. Moreover, the diffraction peaks were broadened due to the smaller size of the particle. The band gap of manganese oxide was calculated from optical absorption, which was carried out by DRS UV-Visible spectroscopy. The morphology of manganese oxide nanoparticles was analyzed by SEM images. The FT-IR analysis confirms the formation of the manganese oxide from manganese oxalate nanoparticles. The electrochemical sensing behavior of manganese oxide nanoparticles were investigated using hydrogen peroxide by cyclic voltammetry.

Electrochemical sensing property of Mn doped Fe3O4 nanoparticles

The Mn doped Fe 3 O 4 nanoparticles were synthesized by hydrothermal method. The prepared nanoparticles were characterized by X-ray diffraction (XRD) analysis, UV-Visible spectroscopy (UV-Vis) and field emission scanning electron microscopy (FE-SEM). The electrochemical sensing property of pure and Mn doped Fe 3 O 4 nanoparticles were examined using uric acid (UA) as an analyte. The obtained results indicated that the Mn doped Fe 3 O 4 nanoparticles exhibited higher electrocatalytic activity towards UA.