Enhanced optical, magnetic, and photocatalytic activity of Mg2+ substituted NiFe2O4 spinel nanoparticles

Recent progress in defect-engineered metal oxides for photocatalytic environmental remediation

Rapid industrial advancement over the last few decades has led to an alarming increase in pollution levels in the ecosystem. Among the primary pollutants, harmful organic dyes and pharmaceutical drugs are directly released by industries into the water bodies which serves as a major cause of environmental deterioration. This warns of a severe need to find some sustainable strategies to overcome these increasing levels of water pollution and eliminate the pollutants before being exposed to the environment. Photocatalysis is a well-established strategy in the field of pollutant degradation and various metal oxides have been proven to exhibit excellent physicochemical properties which makes them a potential candidate for environmental remediation. Further, with the aim of rapid industrialization of photocatalytic pollutant degradation technology, constant efforts have been made to increase the photocatalytic activity of various metal oxides. One such strategy is the introduction of defects into the lattice of the parent catalyst through doping or vacancy which plays a major role in enhancing the catalytic activity and achieving excellent degradation rates. This review provides a comprehensive analysis of defects and their role in altering the photocatalytic activity of the material. Various defect-rich metal oxides like binary oxides, perovskite oxides, and spinel oxides have been summarized for their application in pollutant degradation. Finally, a summary of existing research, followed by the existing challenges along with the potential countermeasures has been provided to pave a path for the future studies and industrialization of this promising field.

A review on the synthesis of metal oxide nanomaterials by microwave induced solution combustion

With the increasing awareness of environmental protection and health, the preparation of metal oxide nanomaterials by environmentally friendly methods is favored by more and more researchers both at home and abroad. The preparation of metal oxide nanomaterials by a microwave-induced solution combustion synthesis method can significantly reduce the reaction time, energy consumption, and the use of toxic chemicals, which is an energy-saving, environmentally friendly method for nanomaterials synthesis. In addition, the microwave-induced solution combustion synthesis (MISCS) method has many advantages such as fast reaction speed, high selectivity, small product size, and homogeneous composition. This paper briefly describes the mechanism of the MISCS and its advantages in the synthesis of metal oxide nanomaterials, the related studies on microwave-induced solution combustion synthesis of metal oxide nanomaterials, and the effects of process parameters on the microstructure and properties of metal oxide nanomaterials synthesized by MISCS. Furthermore, some technical difficulties facing the synthesis of metal oxide nanomaterials by MISCS are summarized, and the future direction has also been prospected.

Structural Morphology and Optical Properties of Strontium-Doped Cobalt Aluminate Nanoparticles Synthesized by the Combustion Method

The study of structural morphology and the optical properties of nanoparticles produced by combustion methods are gaining significance due to their multifold applications. In this regard, in the present work, the strontium-doped cobalt aluminate nanoparticles were synthesized by utilizing Co_1-xSr_xAl₂O₄ (0 ≤ x ≤ 0.5) L-Alanine as a fuel in an ignition cycle. Subsequently, several characterization studies viz., X-ray diffraction (XRD), energy-dispersive X-ray (EDX) analysis, high-resolution scanning electron microscopy (HRSEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet (UV) spectroscopy and vibrating sample magnetometry (VSM) were accomplished to study the properties of the materials. The XRD analysis confirmed the cubic spinel structure, and the average crystallite size was found to be in the range of 14 to 20 nm using the Debye-Scherrer equation. High-resolution scanning electron microscopy was utilized to inspect the morphology of the Co_1-xSr_xAl₂O₄ (0 ≤ x ≤ 0.5) nanoparticles. Further, EDS studies were accomplished to determine the chemical composition. Kubelka-Munk's approach was used to determine the band gap, and the values were found to be in the range of 3.18-3.32 eV. The energy spectra for the nanoparticles were in the range of 560-1100 cm^-1, which is due to the spinel structure of Sr-doped CoAl₂O₄ nanoparticles. The behavior plots of magnetic induction (M) against the magnetic (H) loops depict the ferromagnetic behavior of the nanomaterials synthesized.