Structure-dependent spin-polarized electron transport in twin-crystal Cu1-xEuxO semiconductors

In this work, Eu-doped twin copper oxide (twin Cu1-xEuxO) was synthesized using the gas-liquid phase chemical deposition method in combination with high-temperature oxidation. The incorporation of Eu3+ ions was affected by their diffusivity and the related charge trapping mechanisms. The twin Cu1-xEuxO configuration exhibited significant room-temperature ferromagnetism. From our analysis, it was demonstrated that as the Eu3+ doping concentration increased, the saturation magnetization first increased and then gradually decreased, reaching a peak at 0.82 at%. A p-type to an n-type semiconducting transition was also recorded as the doping concentration increased. A significant anomalous Hall effect characterized by a maximum anomalous Hall coefficient of 1.65, and a maximum Hall conductivity mobility of 16.50 Ohm-1 cm-1 and 250.59 cm2 v-1 s-1, respectively, were derived for the twin Cu1-xEuxO, doped with 0.82 at% at room temperature. First-principles computational simulations were also conducted to elucidate the underlying mechanisms of the magnetic properties, the p-type to n-type transition, and the interplay between the spin-polarized states associated with 4f and carriers. In twin Cu1-xEuxO, the anomalous Hall effect originated from the contribution of the edge-to-jump scattering mechanism. The latter can be significantly enhanced by doping with Eu atoms, which yields the manifestation of the oblique scattering mechanism. Our work paves the way for the development of twin Cu1-xEuxO material structures, which emerge as an ideal candidate for future spintronic applications.

Mesoporous Cobalt Oxide (CoOx) Nanowires with Different Aspect Ratios for High Performance Hybrid Supercapacitors

Cobalt oxide (CoOx) nanowires have been broadly explored as advanced pseudocapacitive materials owing to their impressive theoretical gravimetric capacity. However, the traditional method of compositing with conductive nanoparticles to improve their poor conductivity will unpredictably lead to a decrease in actual capacity. The amelioration of the aspect ratio of the CoOx nanowires may affect the pathway of electron conduction and ion diffusion, thereby improving the electrochemical performances. Here, CoOx nanowires with various aspect ratios were synthesized by controlling hydrothermal temperature, and the CoOx electrodes achieve a high gravimetric specific capacity (1424.8 C g-1) and rate performance (38% retention at 100 A g-1 compared to 1 A g-1). Hybrid supercapacitors (HSCs) based on activated carbon anode reach an exceptional specific energy of 61.8 Wh kg-1 and excellent cyclic performance (92.72% retention, 5000 cycles at 5 A g-1). The CoOx nanowires exhibit great promise as a favorable cathode material in the field of high-performance supercapacitors (SCs).

Intrinsically Conducting Polymer Composites as Active Masses in Supercapacitors

Intrinsically conducting polymers ICPs can be combined with further electrochemically active materials into composites for use as active masses in supercapacitor electrodes. Typical examples are inspected with particular attention to the various roles played by the constituents of the composites and to conceivable synergistic effects. Stability of composite electrode materials, as an essential property for practical application, is addressed, taking into account the observed causes and effects of materials degradation.

Spirulina platensis mediated biosynthesis of Cuo Nps and photocatalytic degradation of toxic azo dye Congo red and kinetic studies

The current research is designed to synthesis Copper oxide nanoparticles (CuO NPs) using Cyanobacterium in greener way. The NPs were synthesized using Spirulina platensis. The method is adopted for the less toxic, less cost and environment friendly method. The synthesized CuO NPs are capped and stabilized by the natural substance of S. platensis including flavonoids, phenolic and acid groups of the microorganism which was confirmed by the GC-MS analysis. Majorly, beta-ionone, p-cumic aldehyde, phytol compounds are identified by GC-MS and it may also involve in the preparation of NPs. Further, the characterization has been carried out using UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction, Scanning electron microscope (SEM), transmission electron microscope (TEM). All the analytical techniques are confirmed the formation of NPs. The formed NPs are showed significant peaks in XRD analysis which further compared with literature. Functional group analysis showed -OH group compounds in extract and it might involve in the formation of NPs. The photo catalytic activity of CuO NPs was showed significant photo degradation of Congo red (CR) dye. The consideration of intense peak, the size of CuO NPs was calculated and found to be 15.2 nm with spherical shape as resulted in morphological identification. The results are showed good photocatalytic activity, since the peak appeared at 230 and 495 nm corresponding to the benzene and azo group of Congo Red were gradually decreased with increase of time. The reaction was found to have nature of pseudo first order reaction. The rate constant was calculated and was found to be - k = 0.3459, which indicates the Congo red degradation was 0.3459 per minute. This study will be a base for budding researchers for their isolation of S. platensis active compounds and with the help of secondary metabolites (active compounds) CuO NPs were synthesized which further acted has degradation agent against Congo red.

Adsorptive removal and photocatalytic degradation of organic pollutants using metal oxides and their composites: A comprehensive review

Metal oxide nanomaterials and their composites are comprehensively reviewed for water remediation. The controlled morphological and textural features, variable surface chemistry, high surface area, specific crystalline nature, and abundant availability make the nanostructured metal oxides and their composites highly selective materials for efficient removal of organic pollutants based on adsorption and photocatalytic degradation. A wide range of metal oxides like iron oxides, magnesium oxide, titanium oxides, zinc oxides, tungsten oxides, copper oxides, metal oxides composites, and graphene-metal oxides composites having variable structural, crystalline and morphological features are reviewed emphasizing the recent development, challenges, and opportunities for adsorptive removal and photocatalytic degradation of organic pollutants viz. dyes, pesticides, phenolic compounds, and so on. It also covers the deep discussion on the photocatalytic mechanism of metal oxides and their composites along with the properties relevant to photocatalysis. High photodegradation efficiency, economically-viable approaches for the preparation of photocatalytic materials, and controlled band-gap engineering make metal oxides highly efficient photocatalysts for degradation of organic pollutants. The review would be an excellent resource for researchers who are currently focusing on metal oxides-based materials for water remediation as well as for those who are interested in adsorptive and photocatalytic applications of metal oxides and their composites.

Wet chemical synthesis of metal oxide nanoparticles: a review

Metal oxide nanoparticles are an important class of nanomaterials that have found several applications in science and technology.

Microwave assisted fabrication of a nanostructured reduced graphene oxide (rGO)/Fe2O3 composite as a promising next generation energy storage material

A supercapacitor electrode material, rGO–Fe₂O₃ composite, prepared by a facile microwave assisted in situ technique, delivers a high specific capacitance of 577.5 F g⁻¹ at a current density of 2 A g⁻¹ with a long cycle life and high rate performance.

Hierarchical CuCo2O4@NiMoO4 core–shell hybrid arrays as a battery-like electrode for supercapacitors

Hierarchical CuCo₂O₄@NiMoO₄ core–shell hybrid arrays exhibit a high specific capacitance, good rate capability and excellent cycling stability.