The natrium superionic conductors (NASICON) family of materials is being widely examined as a solid-state electrolyte for sodium-ion batteries (SIBs). We present a combined experimental and theoretical study of the crystal structure and ionic conductivity of a NASICON NaTi2(PO4)3. Rietveld refinement of the x-ray diffraction pattern reveals that the prepared single phase NaTi2(PO4)3 exhibits rhombohedral symmetry in the R3¯c space group. The elemental analysis by energy dispersive spectroscopy (EDS) confirms the desired composition of NaTi2(PO4)3. The ionic conductivity evaluated from the electrochemical impedance spectroscopy measurements as a function of temperature shows Arrhenius-type relaxation behaviour with activation energy ~0.47(2) eV. A sizable ionic conductivity (~1.16×10-3S/cm at 600K) has been observed for NaTi2(PO4)3. Further, the migration of Na+ via a sigmoidal path in the skeleton of NaTi2(PO4)3 has been investigated by the density functional theory (DFT). The estimated migration energy for the hopping of Na+ between two crystallographic sites is found to be 0.79eV. The calculated conductivity (3.03×10-7S/cm) resulting from the interstitial diffusivity of the Na-ion is consistent with the measured ionic conductivity at room temperature (~1.34×10-7S/cm). While the wide calculated electronic band gap (2.52eV) suggests poor electronic conductivity of NaTi2(PO4)3, it could be beneficial for solid electrolyte applications.

A simple, cost-effective, and facile solvothermal approach has been adopted to synthesize mesoporous CeO2 nanostructures with varying La-doping (2, 4, and 6 mol%) concentrations. Photocatalytic and antibacterial performances are investigated against the inactivation of Escherichia coli and Bacillus licheniformis bacteria cells. Structural and microstructural characterizations of La-doped CeO2 nanostructures are performed by analyzing X-ray diffraction (XRD) data employing the Rietveld refinement method, scanning electron (SEM) and transmission electron microscopy (TEM) images, Brunauer-Emmett-Teller (BET), energy-dispersive Xray (EDX), and X-ray photoelectron spectroscopy (XPS) spectra. Among three doped samples, the 4 mol% Ladoped CeO2 (LCe4) has exhibited high oxygen and Ce3+ concentrations, high microstrain, small crystallite size, and lowest band gap energy, as are revealed by the analysis of XPS, UV-VIS absorption spectra, photoluminescence (PL) spectra, and Rietveld refinement result. The LCe4 sample with the highest number of oxygen vacancies and high surface area shows superior photocatalytic activity (-95% Rhodamin B (RhB) degradation in 130 min, -70% Methylene Blue (MB) degradation within 30 min, and -95% phenol degradation in 180 min under solar radiation). It shows a striking photo-disinfection effect and enhanced antibacterial activity (almost identical to a pure drug) against gram-positive and gram-negative bacteria under visible light irradiation. This novel disinfection and catalytic property of the LCe4 sample is attributed to the mesoporous structure of materials and surface activity, which lowers the electron-hole recombination rate and transports more photogenerated electrons and holes. The nanostructured mesoporous LCe4 material has been used as an effective visible light-activated photocatalyst and photo disinfection for treating wastewater containing organic dyes and gram-negative and gram-positive bacteria. (c) 2023 Elsevier B.V. All rights reserved.

In recent past decades, semiconductor-based photo-catalysts have been studied worldwide as a promising technique for the degradation of organic dyes in wastewater. In this study, a nanoplate-like Bi-based heterojunction (BGB-1,-2, and-3) has been prepared for the first time through the in situ formation of BiBr3 and GaBr3 nanocrystals on the surface of BiOBr via a facile water bath method, followed by the hydrothermal process with a change in the composition. Multiple physiochemical processes such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared are analyzed to reveal the structural properties. The Brunauer-Emmett-Teller, UV-vis diffuse-reflectance, and photoluminescence spectra have been utilized for detailed analysis of the surface area, grain boundary, lattice imperfections, and light absorption properties. The photocatalytic activity and quantum efficiency of the as-synthesized nanocomposites have been evaluated by the photodegradation of Rhodamine B (RhB), methylene blue, methyl orange, Congo red, phenolic compounds, and colorless antibiotic tetracycline with visible-light illumination. Compared to pure BiOBr or the precursor materials, Bi-based nano/photocatalysts exhibit a significantly enhanced photocatalytic activity. Moreover, it is seen that the nanocomposite with a composition of 0.1 mol of Ga(NO3)3 center dot xH2O and 2.9 mol of Bi(NO3)3 center dot 5H2O (BGB-1 nanocomposite) shows the highest photocatalytic activity against RhB degradation (similar to 100% within 20 min) and tetracycline antibiotic (similar to 92% within 20 min). The significantly improved photoreactivity has been ascribed to the effective separation of photogenerated electron-hole pairs and superoxide radical anions (center dot O2-). The hole (h+) also greatly impacts the degradation mechanism. Bi-based nanocomposites are found to kill Gram-positive and Gram-negative bacteria. These nanocomposites have been designed as efficient visible-light-driven heterojunction photocatalytic materials with significant antibacterial activity for wastewater purification.

A simple single-step electrodeposition technique was followed for the three-dimensional (3D)-interconnected binary metallic manganese-cobalt sulfide nanosheets on nickel foam (MnCoS@NF). The architecture and chemical composition of the as-synthesized binder-free electrodes were analyzed by field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The MnCoS@NF achieves exceptionally high specific capacitance (1952.8 F g(-1) at 2 A g(-1)) along with high cycle stability in a three-electrode cell measurement. Furthermore, an aqueous asymmetric supercapacitor (AAS) device was designed using electrodeposited MnCoS@NF in combination with reduced graphene oxide-coated NF (rGO@NF) as a positrode and negatrode, respectively. This device was able to provide very high specific energy (105.1 W h kg(-1)) at a specific power (7.25 kW kg(-1)) along with high cyclic stability (93.9% of specific capacitance retained after 3000 consecutive GCD cycles), which demonstrates its excellent candidature in supercapacitor applications.

This work contains an extensive study on temperature dependent complex dielectric behavior over 4 Hz <_ f <_ 8 MHz of a promising hybrid perovskite, propylammonium lead bromide. The structural, as well as morphological property of this sol-gel derived sample have been analyzed with the help of XRD and SEM respectively. The obtained energy band gap and thermal stability study ensure the capability of this material in device fabrication. Possessing a wide band gap, this perovskite fascinatingly serves as a UV photodetector. The individual impact of grain and grain boundary over the entire resistance has been resolved by Maxwell - Wagner Cole-Cole model. This material holds an amazing property; giant dielectric constant near room temperature at low frequency limit which escalates rapidly in the influence of thermal effect. Modified cole - cole plot assures that both space and free charge conductivities ascend with temperature. The asymmetrical nature of the imaginary part of electric modulus is analyzed by Kohlrausch - Williams - Watts which confirms its non - Debye nature diminishes with rising temperature. The thermally triggered AC conductivity follows Jonscher's power law and is emphasized with the jump relaxation model. The bulk conductivity of the sample depends on temperature and is elucidated with variable range hopping of localized charge carriers. Activation energy plays a key role in the ionic conduction mechanism within the sample, described elaborately. The overall substantial studies on its application as UV detector and different dielectric properties of this sample construct the basis of appreciable acceptability of the sample in energy harvesting. (c) 2021 Elsevier B.V. All rights reserved.