Substantial improvement is needed in efficient and affordable decolorization and disinfection methods to solve the issues caused by dyes and harmful bacteria in water and wastewater. This work involves the photocatalytic degradation of methylene blue (MB) as well as gram-negative and gram-positive bacteria by cobalt-doped tin oxide (Co-SnO2) nanoparticles (NPs) and Co-SnO2/SGCN (sulfur-doped graphitic carbon nitride) nanocomposites (NCs) under sunlight. The coprecipitation approach was used to synthesize the photocatalysts. Maximum methylene blue (MB) photocatalytic degradation was seen with the 7% Co-SnO2 NPs compared to other (1, 3, 5, and 9 wt.%) Co-SnO2 NPs. The 7% Co-SnO2 NPs were then homogenized with different amounts (10, 30, 50, and 70 weight %) of sulfur-doped graphitic carbon nitride (SGCN) to develop Co-SnO2/SGCN heterostructures with the most significant degree of MB degradation. The synthesized samples were identified by modern characterization methods such as FT-IR, SEM, EDX, UV-visible, and XRD spectroscopies. The Co-SnO2/50% SGCN composites showed a significant increase in MB degradation and degraded 96% of MB after 150 min of sunlight irradiation. Both gram-negative (E. coli) and gram-positive (B. subtiles) bacterial strains were subjected to antibacterial activity. All samples were shown to have vigorous antibacterial activity against gram-positive and gram-negative bacteria, but the Co-SnO2/50% SGCNcomposites exhibited the maximum bactericidal action. Thus, the proposed NC is an efficient organic/inorganic photocatalyst that is recyclable and stable without lowering efficiency. Hence, Co-SnO2/50% SGCNNC has the potential to be employed in water treatment as a dual-functional material that simultaneously removes organic pollutants and eradicates bacteria.

/pdf/fabrication-of-effective-co-sno2-sgcn-photocatalysts-for-the-2t2vxr5j.pdf

Fabrication of Effective Co-SnO2/SGCN Photocatalysts for the Removal of Organic Pollutants and Pathogen Inactivation

Cobalt-doped potassium hexa-titanate (Cox:K2Ti6O13 (x = 0.05, 0.10, 0.15 mole%)) ceramics were synthesized by the solid-state reaction method. The XRD patterns confirmed single-phase development in a monoclinic symmetry of various samples, and they were used for different structural calculations of Cox:K2Ti6O13 ceramics. The dielectric constant, tanδ, electrical modulus, and ac conductivity of Co-doped K2Ti6O13 were studied in the temperature range of 100–500 °C. Anomalies were observed in graphs of the dielectric constant versus temperature, showing the transition phase in the studied samples. Dielectric peaks at transition temperature decreased with an increasing frequency, and the peaks shifted toward higher temperatures, illustrating the relaxation of the dielectric materials. The composition with x = 0.10 showed low dielectric loss and a higher dielectric constant and can be utilized for high-temperature dielectric material. Small doping of cobalt improved the ac conductivity of K2Ti6O13 ceramics due to the increase in the spin–phonon interaction and dominant electron hopping conduction; however, the conductivity diminished with substantial doping because of the contraction of the tunnel space and ambushing of conduction electrons. The uniqueness of this study is in the high dielectric optimization of lead-free ceramic Cox:K2Ti6O13 and the discovery of positive temperature coefficients of the resistivity of these ceramic samples.

/pdf/study-of-co-doped-k2ti6o13-lead-free-ceramic-for-positive-3dh7mgd3.pdf

Study of Co-Doped K2Ti6O13 Lead-Free Ceramic for Positive Temperature Coefficient Thermistor Applications

Magnetoelectric, and Dielectric Switching Properties of Co-Doped Bifeo3 for Low Energy Memory Technology: A First-Principles Study

Study of doped-doped ZnO thin films deposited by low-cost spin coating

First-principles calculations are carried out to grow half-metallicity, tune dielectric and magnetoelectric properties of pure and doped bismuth ferrite BiFeO3 (BFO) with lanthanum (La) at A-site and cobalt (Co) at B-site as mono- and co-dopants. These calculations are performed in the Cambridge Serial Total Energy Package (CASTEP) code using ultra-soft pseudopotential (USP). A large band gap has been observed in the pure rhombohedral phase. The Co impurity atom is more favorable to decrease the band gap while La pushes the BFO towards half-metallic behavior, which develops 100% polarization in all doped BFO systems. From the dielectric response of BFO, high spin current density <s> of 8.7 × 103 A/m2 and charge current density (j) of 6.3 × 10–11 A/m2 have been observed in the La doped system. In the case of magnetic properties, the strong magnetization (M) 32.13 MA/cm2 and the large magnetoelectric coupling coefficient of 6.72× 10−6 s/m have been observed in co-doped BFO. 

Magnetoelectric, and dielectric based switching properties of co-doped BiFeO3 for low energy memory technology: A first-principles study

La and Mn co-doped Bi1−xLaxFe0.97Mn0.03O3 (BLFMOx, x = 0.05, 0.1, 0.2) ceramics were prepared by solid-state reaction method, and their structural, magnetic, dielectric and magnetocapacitance properties were studied. It was discovered that the co-substitution of La & Mn at sites of Bi & Fe suppressed impure phases which normally occur in BiFeO3 synthesis. BLFMOx samples were calcinated, and well crystalline phases were acquired at a sintering temperature of 950 °C. X-rays diffraction patterns of the samples were recorded and investigated for the affirmation of crystal structure and determination of the lattice parameters. The normal grain size of the samples was observed to be between 1 and 2 μm. M–H graphs of BiFeO3 and BLFMO0.05 ceramics consist of straight-line, confirming antiferromagnetic nature of samples. Dielectric constant was diminished with increase in frequency for each composition. BLFMOX ceramics showed negative magnetocapacitance and decrease in dielectric constant with magnetic field. Relative difference in dielectric constant initiated by external magnetic field might be approximated by ∆e/e = kM2 for BLFMOX, and here, magnetoelectric interaction (k) is negative.

Study of Structural, Magnetic, Dielectric Properties and Estimation of Magnetoeletric Coupling of La, Mn co-doped Bi 1−x La x Fe 0.97 Mn 0.03 O 3 Ceramics

In this work, the radio frequency magnetron sputtering technique (RF sputtering) was utilized for the deposition of Y2O3-doped zinc oxide (ZnO) thin films on a SiO2 substrate. The microstructures and optical properties of the thin films deposited utilizing various gas (Ar:O2) ratios at 400 °C were characterized. XRD investigation of thin films demonstrates that all deposited films are polycrystalline and there is a single phase hexagonal wurtzite type structure with a strong (002) orientation. An increment of O2 in the gas mixture reduces the intensity of peak (002). Y2O3-doped ZnO thin films exhibited denser morphology with refined microstructure as compared to pure ZnO films. The absorbance and transmittance of doped ZnO thin films were measured by UV-VIS-IR spectrophotometer in the wavelength range 300 nm to 800 nm. High transmittance in the visible region and high band gap of films were revealed. Photoluminescence (PL) of films was estimated at the excitation wavelength of 325 nm and it uncovered two PL peaks present in UV and visible regions (400 nm to 445 nm). The effect of Ar:O2 gas proportion on stoichiometry, structural and optical properties of the Y2O3-doped ZnO thin films was also revealed. FullText for HTML: https://doi.org/10.1209/0295-5075/129/34003

M. Sowjanya

Papers

Study of Structural, Magnetic, Dielectric Properties and Estimation of Magnetoeletric Coupling of La, Mn co-doped Bi 1−x La x Fe 0.97 Mn 0.03 O 3 Ceramics

Effect of Ar:O2 gas atmosphere on optical properties of Y2O3-doped ZnO thin films by RF sputtering