Enhanced electrochemical performance of α-MoO3/graphene nanocomposites prepared by an in situ microwave irradiation technique for energy storage applications

Graphene-Based Multi-Nanocomposites: Synthesis, Characterization and Photodegradation Analysis

In this study, Hummer's method was modified to synthesize graphene oxide (GO). GO-based nanocomposites GO/ZnO, GO/MoO3, and GO/ZnO/MoO3 were synthesized using co-precipitation and solid-state reaction methods. The prepared GO and nanocomposites were characterized using UV-Visible spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). SEM images showed distinct morphological differences among GO, GO/ZnO, and GO/MoO3, while UV-Visible and Raman spectroscopy demonstrated the influence of ZnO and MoO3 on the optical properties and interactions of GO. Using visible light irradiation, photocatalytic degradation studies showed improved results for the GO/MoO3 nanocomposites. The 93% degradation of methylene blue (MB) achieved by GO/MoO3 after 280 minutes was greater than that of GO/ZnO/MoO3 (92% degradation at 360 minutes) and GO/ZnO (93% degradation at 340 minutes) within the same period. High efficiency photodegradation of methylene blue (MB) under visible light irradiation of GO/MoO3 nanocomposites were shown by these findings, demonstrating their strong potential for environmental remediation applications.

Microwave-Assisted Synthesis as a Promising Tool for the Preparation of Materials Containing Defective Carbon Nanostructures: Implications on Properties and Applications

In this review, we focus on a small section of the literature that deals with the materials containing pristine defective carbon nanostructures (CNs) and those incorporated into the larger systems containing carbon atoms, heteroatoms, and inorganic components.. Briefly, we discuss only those topics that focus on structural defects related to introducing perturbation into the surface topology of the ideal lattice structure. The disorder in the crystal structure may vary in character, size, and location, which significantly modifies the physical and chemical properties of CNs or their hybrid combination. We focus mainly on the method using microwave (MW) irradiation, which is a powerful tool for synthesizing and modifying carbon-based solid materials due to its simplicity, the possibility of conducting the reaction in solvents and solid phases, and the presence of components of different chemical natures. Herein, we will emphasize the advantages of synthesis using MW-assisted heating and indicate the influence of the structure of the obtained materials on their physical and chemical properties. It is the first review paper that comprehensively summarizes research in the context of using MW-assisted heating to modify the structure of CNs, paying attention to its remarkable universality and simplicity. In the final part, we emphasize the role of MW-assisted heating in creating defects in CNs and the implications in designing their properties and applications. The presented review is a valuable source summarizing the achievements of scientists in this area of research.

Electrical conductivity and electrochemical studies of Cr-doped MoO3 nanoflakes for energy storage applications

The growing demand for electricity has increased the interest of the researchers towards exploration of energy storing devices (ESDs). With the motif for developing electrochemical energy storage devices, this research work is focussed on the study of MoO₃ nanoparticles and its doping with chromium as an efficient electrode material for energy storage applications. The nanoparticles were synthesized by hydrothermal method and were examined by powder X-ray diffraction, which determined the thermodynamically stable orthorhombic phase of MoO₃, and their morphologies were examined using scanning electron microscopy displaying flake-like structures. The typical vibrational bands of Mo-O were identified from Infra-red and Raman spectral analysis. The ultra violet diffuse reflectance spectra revealed the decrease in optical band gap after doping with chromium. The temperature dependent AC and DC conductivities were enhanced on doping. Electrochemical behaviour of the nanoparticles was probed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) measurements and galvanostatic charge-discharge (GCD) analysis for which specific capacitance (C _sp) value of 334 Fg^-1 was achieved for Cr-doped MoO₃ nanoparticles. The electrochemical performance of the sample was found to be increased after doping with Cr.

Microwave as a Tool for Synthesis of Carbon-Based Electrodes for Energy Storage

This Spotlight on Applications highlights the significant impact of microwave-assisted methods for synthesis and modification of carbon materials with enhanced properties for electrodes in energy storage applications (supercapacitors and batteries). For the past few years, microwave irradiation has been increasingly used for the synthesis of carbon materials with different morphologies using various precursors. Microwave processing exhibits numerous advantages, such as short processing times, high yield, expanded reaction conditions, high reproducibility, and high purity of products. On this frontier research area, we have discussed microwave-assisted synthesis, defect creation, simultaneous reduction and exfoliation, and heteroatom doping in carbon materials. By careful manipulation of microwave irradiation parameters, the method becomes a powerful and efficient tool to generate different morphologies in carbon-based materials. Other important outcomes are the flexible control over the degree of reduction and exfoliation of graphene derivatives, the generation of defects in graphene-based materials by metals, the intercalation of metal oxides into graphene derivatives, and heteroatom doping of graphene materials. The Spotlight on Applications aims to provide a condensed overview of the current progress in carbon-based electrodes synthesized by microwave, pointing out outstanding challenges and offering a few suggestions to trigger more research endeavors in this important field.