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In this context, we synthesize pristine and transition metal (Fe, Co, Ni, and Cu) (TM)-doped uniform, 3D-rhombohedral manganese carbonate (MnCO3) microcrystals using a simple hydrothermal method. T...

A novel Gd2O3 nanosheet was synthesized by the template-free chemical coprecipitation method. Interestingly, upon calcination at 600 °C, nanoparticles were transformed into a nanosheet, as observed from field emission scanning electron microscopy (FESEM) images. An increase in the calcination temperature to 600 °C increases the particle size to 50 nm, which results in aggregation. A sheetlike Gd2O3 exhibits superparamagnetism from 300 K. The highly selective nonenzymatic sensing of riboflavin (RF) was studied using a modified glassy carbon electrode with Gd2O3 nanosheets, and its various applications were made possible by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The redox behavior of the RF was determined. The newly fabricated sensor showed high sensitivity, stability, and reproducibility and was also tested with a commercial vitamin B2 tablet and a milk powder sample.

The proposed work is focused on the effect of substrates on the electrocatalytic performance of physical vapor deposited vanadium pentoxide (V2O5) films. V2O5 thin films were prepared onto various substrates such as glass, indium doped tin oxide (ITO), fluorine doped tin oxide (FTO), aluminum (Al) and copper (Cu). XRD patterns revealed that the evaporated V2O5 films were a single crystalline orthorhombic structure with the predominant orientation along the (001) lattice plane. In order to understand the influence of substrates' effect on the structural properties, various microstructural parameters such as crystallite size (D), dislocation density (δ), microstrain (e) texture coefficient and stacking fault probability (α) for preferential orientation were evaluated and discussed in detail. Tauc's plot was used to determine the band gap of V2O5 thin films and found to be 2.1 eV for the film deposited on the ITO substrate. SEM and AFM analyses revealed that physical vapored V2O5 thin films are densely packed with uniform morphological and topographical features. Significantly, to the best of our knowledge; the feasibility of V2O5 thin films for the electrochemical performance towards the detection of hydrazine oxidation was demonstrated for the first time using cyclic voltammetric studies. V2O5 thin films coated on ITO substrates exhibited better catalytic activity with a mass catalytic activity of 3320 mA g−1. These findings will provide a new avenue for electrocatalytic activity of hydrazine oxidation based on V2O5 thin films and will be extremely important for the selection of a suitable substrate in the field of sensor and actuator technology.

Highly oriented vanadium pentoxide (V2O5) thin films were grown by electron beam (EB) evaporation on glass substrates at 473 K. V2O5 thin films were coated with various thicknesses (≈800–1200 nm) by varying the distance from the source and substrates. The influence of film thickness on its physical properties was deeply studied by various characterization techniques. XRD studies were performed to investigate the structural confirmation and preferential lattice orientation of EB evaporated films. The Voigt profile method was used to estimate the microstructural parameters and to elaborately discuss its dependency on film thickness. SEM micrographs perceived that the prepared films were nearly homogeneous with densely packed morphology. AFM topographical images depicted the nanograins on the surface of the films. Raman spectra confirmed the formation of the α-V2O5 polymorph without secondary phase formation. From the optical absorption data, the indirect optical band gap ‘Eg’ was found to be 2.36 eV for V2O5 thin film with higher thickness. Optical constants such as refractive index (n), extinction coefficient (k), optical conductivity (σ) and dielectric constants (e) were evaluated using an approximation protocol developed from well recognized procedures using the data obtained from the UV-Vis spectroscopic technique. The luminescence property variations were observed by photoluminescence (PL) spectroscopy and it has elucidated the role of film thickness in the EB evaporated V2O5 films. The Hall mobility and carrier density were found to increase with film thickness.

Zn1–xCoxO (x = 0, 0.05, 0.10, and 0.15) nanoparticles (NPs) were synthesized by a coprecipitation method. The crystalline sizes of synthesized samples were calculated from the powder XRD patterns, which were found to decrease with the increase of cobalt content. The FT-IR spectra confirmed the Zn–O stretching bands at 468, 456, 452, and 461 cm–1 for the respective ZnO NPs. SEM images demonstrated the distinct flowerlike morphology. The photoluminescence spectra of all the samples exhibited a broad emission in the visible range. XPS studies were carried out for Zn0.90Co0.10O NPs. The carriers (donors) bound on the Co sites were observed from the micro-Raman spectroscopic studies. The pure and Co-doped ZnO NPs showed significant changes in the M–H loop where the diamagnetic behavior of ZnO changes to ferromagnetic nature when doping with Co. Oxygen vacancies and zinc interstitials were found to be the main reasons for room-temperature ferromagnetism in the Co-doped ZnO NPs with the support of the results ob...