Khemchand Dewangan

Synthesis and characterization of single-crystalline α-MoO3 nanofibers for enhanced Li-ion intercalation applications

High quality, single-crystalline alpha-MoO3 nanofibers are synthesized by rapid hydrothermal method using a polymeric nitrosyl-complex of molybdenum(II) as molybdenum source without employing catalysts, surfactants, or templates. The possible reaction pathway is decomposition and oxidation of the complex to the polymolybdate and then surface condensation on the energetically favorable 001] direction in the initially formed nuclei of solid alpha-MoO3 under hydrothermal conditions. Highly crystalline alpha-MoO3 nanofibers have grown along 001] with lengths up to several micrometres and widths ranging between 280 and 320 nm. The alpha-MoO3 nanofibers exhibit desirable electrochemical properties such as high capacity reversibility as a cathode material of a Li-ion battery.

Onsite-detection of barium and nickel from river, pond and tap water samples using gold nanoparticles as a chemical sensor

We report a simple, selective and sensitive colorimetric assay for onsite determination of Ni(II) and Ba(II) from river, pond and tap water samples using the localized surface plasmon resonance (LSPR) of malonate capped gold nanoparticles (AuNPs) as a chemical sensor. The method is based on the color change and red shift of LSPR absorption band in visible region that caused by the aggregation of NPs because of the coordination complex between Ba(II) and Ni(II) with carboxylate ions of malonate capped AuNPs. The determination of Ba(II) and NI(II) in a same sample was performed by masking one of the analyte at a time, EDTA was used to mask Ni(II) for detection of Ba(II) and dilute H2SO4 was used to mask the Ba(II) for detection of Ni(II). The linear range for quantitative determination of Ba(II) and NI(II) were found in the range of 15-500 and 10-500ngmL-1 with a limit of detection of 5 and 3ngmL-1, respectively. The advantages of the AuNPs based chemical sensor is found to be simple, rapid and sensitive as well as it can be applied at the sample source for trace detection of Ba(II) and Ni(II) in various environmental samples.

Surfactant-based dispersive liquid–liquid microextraction for the determination of zinc in environmental water samples using flame atomic absorption spectrometry

Zinc metal is an essential micronutrient which is required for different biological and physiological processes in humans, animals and plants. Here, a simple, rapid and sensitive method for the determination of zinc in environmental water samples using surfactant-assisted dispersive liquid–liquid micro-extraction (SA-DLLME) prior to flame atomic absorption spectrometry (FAAS) analysis has been reported. This method involved the formation of a zinc complex with 4-(2-pyridylazo) resorcinol (PAR) and subsequently SA-DLLME was applied to extract the Zn(II)–(PAR)2·CPC complex into chloroform in the presence of a cationic surfactant. Optimum extraction of the complex was observed when the concentration of cetylpyridinium chloride (CPC) and PAR was 0.1% for both at pH 9.0 and with an extraction time of 10 min. The calibration curve was found to be linear over the range of 1.5–60 μg L−1 with a correlation of estimation (r2) of 0.997. This optimized method has been successfully applied for the determination of zinc in environmental water (tap, river and well) samples.