Caroline Ponraj

Knowledge of electronic band structure and its role on the electronic transport as well as optical properties of semiconducting as well as insulating materials are important to characterize/evaluate their potential for practical applications. In this work, the crystallographic, morphological, electronic transport, optical and electronic band structure properties of three Lanthanum (La) based double perovskite oxides, La₂ZnMnO₆, La₂NiTiO₆ and La₂NiRuO₆ were evaluated and compared. Polycrystalline samples were synthesized by following the solid-state reaction method. Analysis of powder x-ray diffraction (XRD) data indicates monoclinic (space group: P2₁/n) crystal structure. The unit cell size of these three systems correlates with their constituent transition metal ionic sizes. Analysis of Raman spectra and Fourier transform infrared (FTIR) spectra indicates that the octahedral vibrational modes correlate with the ionic mass of the constituent transition metals for these three systems. The temperature depended resistivity data (ρ(T)) indicate semiconducting behaviour for all the three systems. Among the samples, the La₂NiRuO₆ system shows lowest ρ(T) and the La₂NiTiO₆ system shows the highest ρ(T) values. The thermal activation energy is extracted from the analysis of ρ(T) data, following the thermally activated transport model. The estimated activation energy values are 134(8) meV for La₂NiRuO₆, 203(1) meV for La₂ZnMnO₆ and 280(5) meV for La₂NiTiO₆, respectively. Also, it is observed that the normalized resistivity and activation energy of the three systems follow a direct/simple scaling trend. Additionally, diffuse reflectance spectroscopy (DRS) measurements were carried out on these systems. The DRS results further supports the observed trend in ρ(T) data among the three systems. The experimental observations is further supported by the density functional theory calculations.

Active pharmaceutical ingredients have emerged as an environmentally undesirable element because of their widespread exploitation and consequent pollution, which has deleterious effects on living things. In the pursuit of sustainable environmental remediation, biomedical applications, and energy production, there has been a significant focus on two-dimensional materials (2D materials) owing to their unique electrical, optical, and structural properties. Herein, we have synthesized 2D zinc oxide nanosheets (ZnO NSs) using a facile and practicable hydrothermal method and characterized them thoroughly using spectroscopic and microscopic techniques. The 2D nanosheets are used as an efficient photocatalyst for antibiotic (herein, end-user ciprofloxacin (CIP) was used as a model antibiotic) degradation under sunlight. It is observed that ZnO NSs photodegrade ~ 90% of CIP within two hours of sunlight illumination. The molecular mechanism of CIP degradation is proposed based on ex-situ IR analysis. Moreover, the 2D ZNO NSs are used as an antimicrobial agent and exhibit antibacterial qualities against a range of bacterial species, including Escherichia coli, Staphylococcus aureus, and MIC of the bacteria are found to be 5 μg/l and 10 μg/l, respectively. Despite having the biocompatible nature of ZnO, as-synthesized nanosheets have also shown cytotoxicity against two types of cancer cells, i.e. A549 and A375. Thus, ZnO nanosheets showed a nontoxic nature, which can be exploited as promising alternatives in different biomedical applications.

In this population driven society, the major cause of environmental pollution is due to modern agricultural practices & intensified industrialization. These kind of economic practices leads to excessive deposition of residual pesticides, heavy metals in both soil and water. This is a commonly accepted agreement that there is an immediate need for qualitative and quantitative information on environmental entities. Electrochemical sensing platforms which offers in situ and rapid detection of wide range of pollutants gives good results compared to other conventional methods. “Graphene” a wonder material possessing excellent physiochemical properties when utilized as an electrode for sensing, enables quicker diffusion of target analytes and detects environmental contaminants even at trace levels. The main motive of the manuscript is to give some new insights on graphene based electrochemical sensors on detecting some environmental entities like pesticides, heavy metals & antibiotics. It also highlights the growth & performance of the sensors over the years in detecting these hazardous pollutants. In addition, this review also gives a better understanding on its methods and techniques, existing challenges and future aspects.

Citric acid assisted auto combustion method was used in the synthesis of BiFeO₃ nanoparticles. The synthesized nanoparticles were characterised using X-ray powder diffraction, Scanning electron Microscope, BET surface area analysis, UV-Visible Diffuse Reflectance Spectrometer and Vibratory Sample Magnetometer. The photocatalytic behaviour of the BFO nanoparticles has been studied by the degradation of the direct blue dye. It is observed that BFO shows a good photocatalytic degradation of dye in the visible light irradiation. The effect of pH, catalyst quantity has been studied. The optimum condition is identified as pH 2 and 150mg of the photocatalyst in 10ppm of the dye solution. The magnetic property of BiFeO₃at room temperature helps in the efficient removal of them from the treated dye solution. The ability of BiFeO₃ nanoparticles to absorb the solar energy and using it for the treatment of water gives it an upper hand over other photo catalysts like Titanium Oxide (TiO₂) and Zinc Oxide (ZnO).