Non‐precious transition metal oxide nanomaterials: Synthesis, characterization, and electrochemical applications

Thermal and electrical properties of PVDF modified Co3O4 functionalized MWCNTs

This research examines the synthesis of Co3O4-MWCNTs nano-hybrid structures and their incorporation into PVDF polymer nanocomposite thin films via the solution casting method. The study comprehensively characterizes the structural, thermal, and electrical properties of the resulting nanocomposites using techniques such as SEM, XRD, FTIR, TGA, TDA, DSC, and impedance spectroscopy. XRD confirmed the crystalline structure and phase transition of the PVDF/Co3O4-MWCNTs nanocomposites, while FTIR analysis revealed the presence of α- and β-phases of PVDF. TGA, TDA, and DSC results revealed enhanced thermal stability, highlighting the potential for high-temperature applications. Notably, the dielectric properties significantly improved at 0.5 wt% Co3O4 and 0.3 wt% MWCNTs. The electrical conductivity of the nanocomposites increased with higher nano-hybrid content, owing to strong interactions between the PVDF polymer and nano-fillers. This work provides insight into the development of advanced nanocomposites with superior thermal and electrical properties, which could be used in electronic and energy storage devices. The novelty of this study lies in the effective combination of Co3O4 and MWCNTs to enhance the properties of PVDF, offering a promising material for future industrial applications.

Electrochemical Determination of Doxorubicin in the Presence of Dacarbazine Using MWCNTs/ZnO Nanocomposite Modified Disposable Screen-Printed Electrode

In the current work, the MWCNTs/ZnO nanocomposite was successfully synthesized using simple method. Then, FE-SEM, XRD, and EDX techniques were applied for morphological and structural characterization. Afterward, a sensitive voltammetric sensor based on modification of a screen-printed carbon electrode (SPCE) using MWCNTs/ZnO nanocomposite was developed for the determination of doxorubicin in the presence of dacarbazine. To evaluate the electrochemical response of the MWCNTs/ZnO/SPCE towards doxorubicin, cyclic voltammetry (CV) was applied. The MWCNTs/ZnO nanocomposite showed a significant synergistic effect on the electrochemical response of the electrode for the redox reaction of doxorubicin. Also, the MWCNTs/ZnO/SPCE demonstrated an enhanced sensing platform for the quantification of doxorubicin, obtaining a detection limit (LOD) of 0.002 µM and a sensitivity of 0.0897 µA/µM, as determined by differential pulse voltammetry (DPV) within a linear range from 0.007 to 150.0 µM. Also, the MWCNTs/ZnO nanocomposite-modified SPCE showed high electrochemical activities towards the oxidation of doxorubicin and dacarbazine with peak-potential separation of 345 mV, which is sufficient for doxorubicin determination in the presence of dacarbazine. Also, the MWCNTs/ZnO nanocomposite-modified SPCE presented reproducible and stable responses to determine doxorubicin. Finally, the developed platform demonstrated a successful performance for doxorubicin and dacarbazine determination in real samples, with recovery in the range of 97.1% to 104.0% and relative standard deviation (RSD) from 1.8% to 3.5%.

Review of Anodic Tantalum Oxide Nanostructures: From Morphological Design to Emerging Applications

Anodization of transition metals, particularly the valve metals (V, W, Ti, Ta, Hf, Nb, and Zr) and their alloys, has emerged as a powerful tool for controlling the morphology, purity, and thickness of oxide nanostructures. The present review is focused on the advances in the synthesis of micro/nanostructures of anodic tantalum oxides (ATO) in inorganic, organic, and mixed inorganic-organic type electrolytes with critically highlighting anodization parameters, such as applied voltage, current, time, and electrolyte temperature. Particularly, the growth of ATO nanostructures in fluoride containing electrolytes and their applications are briefly covered. The details of the current- or voltage-time transient and its relation to the growth of the anodic oxide films are presented systematically. The main discussion revolves around the incorporation of various electrolyte species into the surface of ATO structures and its effects on their physicochemical properties. The latest progress in understanding the growth mechanism of nanoporous/nanotubular ATO structures is outlined. Additionally, the impact of annealing temperature (ranging from 400-1000 °C) and atmosphere on the crystalline structure, morphology, impurity content, and physical properties of the ATOs is briefly described. The common modification methods, such as decorating with other transition metal/metal oxide, heteroatom doping, or generating defects in the ATO structures, are discussed. Besides, the review also covers the most promising applications of these materials in the fields of capacitors, supercapacitors, memristive devices, corrosion protection, photocatalysis, photoelectrochemical (PEC) water splitting, and biomaterials. Finally, future research directions for designing ATO-based nanomaterials and their utilities are indicated.

MoO3/WO3/rGO as electrode material for supercapacitor and catalyst for methanol and ethanol electrooxidation

The potential of metal oxides in electrochemical energy storage encouraged our research team to synthesize molybdenum oxide/tungsten oxide nanocomposites (MoO3/WO3) and their hybrid with reduced graphene oxide (rGO), in the form of MoO3/WO3/rGO as a substrate with relatively good electrical conductivity and suitable electrochemical active surface. In this context, we presented the electrochemical behavior of these nanocomposites as an electrode for supercapacitors and as a catalyst in the oxidation process of methanol/ethanol. Our engineered samples were characterized by X-ray diffraction pattern and scanning electron microscopy. As a result, MoO3/WO3 and MoO3/WO3/rGO indicated specific capacitances of 452 and 583 F/g and stability of 88.9% and 92.6% after 2000 consecutive GCD cycles, respectively. Also, MoO3/WO3 and MoO3/WO3/rGO nanocatalysts showed oxidation current densities of 117 and 170 mA/cm2 at scan rate of 50 mV/s, and stability of 71 and 89%, respectively in chronoamperometry analysis, in the MOR process. Interestingly, in the ethanol oxidation process, corresponding oxidation current densities of 42 and 106 mA/cm2 and stability values of 70 and 82% were achieved. MoO3/WO3 and MoO3/WO3/rGO can be attractive options paving the way for prospective alcohol-based fuel cells.