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This study investigates the potential of cerium (Ce) doping to improve the performance of cobalt oxide (Co₃O₄) nanoparticles as battery-type supercapacitor electrodes. Pure Co₃O₄ nanoparticles were synthesized via a solution combustion method and then doped with 2.5 % (Ce-Co 3 O 4) and 5 % Ce (CeO 2 -Co 3 O 4). Comprehensive characterization, including X-ray diffraction (XRD), Raman spectroscopy, and field emission scanning electron microscopy (FESEM), was used to analyze the impact of Ce doping on the material properties. XRD analysis confirmed the successful incorporation of Ce into the Co₃O₄ structure, with distinct CeO 2 phases forming at higher doping levels. Ce doping resulted in decreased crystallite size and peak intensity, indicating reduced crystallinity and increased defect concentration. Raman spectroscopy corroborated these findings, showing a redshift that suggests weakened metal-oxygen bonds and smaller grain sizes due to Ce³⁺ incorporation. FESEM images demonstrated that Ce doping effectively reduced nanoparticle agglomeration, with 2.5 % doping leading to smaller particles and 5 % doping promoting a 2D flake-like morphology with increased porosity. Nitrogen adsorption-desorption measurements revealed a significant increase in surface area and pore volume for CeO 2 -Co₃O₄, facilitating improved electrolyte diffusion and reduced resistance, thereby enhancing electrochemical performance. Evaluation of the electrochemical properties of undoped and Ce-doped Co₃O₄ materials revealed a battery-like response in a three-electrode configuration. Notably, the CeO 2 -Co 3 O 4 exhibited a superior specific capacity of 603.3 C g−1 at a current density of 1 A g−1, significantly exceeding the values of 368.5 C g−1 and 127.1 C g−1 achieved by Ce-Co 3 O 4 and undoped Co 3 O 4 , respectively. Furthermore, the CeO 2 -doped Co 3 O 4 demonstrated exceptional cyclic stability, retaining 87 % of its initial capacity after undergoing 5000 charge-discharge cycles at a high current density of 10 A g−1. These results suggest that Ce doping is a promising strategy for optimizing Co₃O₄-based battery-type electrode materials, potentially leading to the development of high-performance and cost-effective energy storage systems. [ABSTRACT FROM AUTHOR]

The hydrothermal method has been utilized to synthesize graphitic carbon nitride (g-C3N4) polymers and cobalt oxide composites effectively. The weight percentage of g-C3N4 nanoparticles influenced the electrochemical performance of the Co3O4-g-C3N4 composite. In an aqueous electrolyte, the Co3O4-g-C3N4 composite electrode, produced with 150 mg of g-C3N4 nanoparticles, revealed remarkable electrochemical performance. With an increase in the weight percentage of g-C3N4 nanoparticles, the capacitive contribution of the Co3O4-g-C3N4 composite electrode increased. The Co3O4-g-C3N4-150 mg composite electrode shows a specific capacitance of 198 F/g. The optimized electrode, activated carbon, and polyvinyl alcohol gel with potassium hydroxide were used to develop an asymmetric supercapacitor. At a current density of 5 mA/cm2, the asymmetric supercapacitor demonstrated exceptional energy storage capacity with remarkable energy density and power density. The device retained great capacity over 6k galvanostatic charge–discharge (GCD) cycles, with no rise in series resistance following cyclic stability. The columbic efficiency of the asymmetric supercapacitor was likewise high. [ABSTRACT FROM AUTHOR]

Lithium batteries, as a type of advanced battery technology, have extremely high application value. However, lithium-ion batteries are prone to aging and malfunction after prolonged charging and discharging, which affects their performance. The correct selection of electrode materials can improve the service life of lithium-ion batteries. In order to optimize the electrochemical materials of lithium-ion batteries, this study conducted electrochemical analysis on graphene oxide (GO) and Co3O4 (GO/Co3O4) nanocomposites used as anodes of longacting lithium-ion batteries. The GO/Co3O4 nanocomposites were synthesized by using hydrothermal method, and the properties of GO/Co3O4 nanocomposites were analyzed. X-ray diffraction (XRD) analysis showed that Co3O4 nanoparticles were uniformly formed on the surface of GO nanosheets. The GO/Co3O4 nanocomposite electrode had 50% by weight (wt) of Co3O4 according to electrochemical characterizations of the GO, Co3O4, and GO/Co3O4 electrodes in lithium-ion batteries. The capacity was found to increase when the Co3O4 content was increased to 50% of the sample, while the capacity decreased as Co3O4 concentration increased. The GO/Co3O4 nanocomposite electrode that contained 50 wt% Co3O4 exhibited excellent cyclic stability, delivering more than 1,115 mA h/g at a current density of 0.1 A/g with minimal capacity loss, a Coulombic efficiency that approached almost 99.5% over 500 cycles, and good capacity retention (95%). Therefore, GO/Co3O4 nanocomposite could be an appropriate electrode material with improved cycling stability. The results of this study provided a good direction for the optimization of electrode materials and electrochemical research in lithium batteries. [ABSTRACT FROM AUTHOR]

The green, sustainable, and inexpensive creation of novel materials, primarily nanoparticles, with effective energy-storing properties, is key to addressing both the rising demand for energy storage and the mounting environmental concerns throughout the world. Here, an orange peel extract is used to make cobalt oxide nanoparticles from cobalt nitrate hexahydrate. The orange peel extract has Citrus reticulata, which is a key biological component that acts as a ligand and a reducing agent during the formation of nanoparticles. Additionally, the same nanoparticles were also obtained from various precursors for phase and electrochemical behavior comparisons. The prepared Co-nanoparticles were also sulfurized and phosphorized to enhance the electrochemical properties. The synthesized samples were characterized using scanning electron microscopic and X-ray diffraction techniques. The cobalt oxide nanoparticle showed a specific capacitance of 90 F/g at 1 A/g, whereas the cobalt sulfide and phosphide samples delivered an improved specific capacitance of 98 F/g and 185 F/g at 1 A/g. The phosphide-based nanoparticles offer more than 85% capacitance retention after 5000 cycles. This study offers a green strategy to prepare nanostructured materials for energy applications. [ABSTRACT FROM AUTHOR]

The nanostructured Co3O4 particles were prepared by a simple and inexpensive precipitation method, which can be used as electrode materials in pseudocapacitive energy storage devices. The effect of temperature on the crystal structure and morphology of the material was discussed to obtain a suitable condition for the fabrication of the electrodes. The results showed that the Co3O4 calcined at 400 °C (C4) with an average particle size of 34.1 ± 4.0 nm is suitable for electrode fabrication. This is due to the superior electrical conductivity and high purity of the phase structure with a larger specific surface area and porosity compared to the samples calcined at 600 and 800 °C. Moreover, the different oxidation states of Co ions in electrochemical reactions are the main factor for the high capacitance values of the sample. The maximum specific capacitance of 115.3 F/g at a current density of 1 A/g was achieved by the C4 sample. The charge/discharge stability measurements with maximum a of 5000 cycles showed that the sample can achieve excellent retention of specific capacitance of almost 100% for up to 1900 cycles at a current density of 5 A/g. [ABSTRACT FROM AUTHOR]

In this work, the effects of different Co 3 O 4 :KOH mass ratios on the microstructure, chemical state, and surface properties of Co 3 O 4 nanoparticles were investigated and discussed. The different KOH contents in the activation process affecting the electrochemical properties of the samples were determined in a three-electrode configuration. The results showed that the sample with a Co 3 O 4 :KOH mass ratio of 1:0.5 (Co@0.5KOH) exhibited the highest specific capacitance of 204.0 F/g at a current density of 1 A/g. The excellent capacitance retention of 97.7% was observed after a 5000 cycle galvanostatic charge/discharge test. A symmetrical two-electrode system was set up, and the results showed that the Co@0.5KOH sample had a superior energy density of 3.5 Wh/kg and a power density of 276.0 W/kg at a current density of 1 A/g. The KOH activation method was effective and could be extended to other metal oxides to obtain better electrode materials for supercapacitors. [Display omitted] • KOH activation promotes formation of oxygen vacancies on Co 3 O 4 surface. • KOH activation affects the enhanced hydrophilic functional group on Co 3 O 4 particles. • The surface-modified Co 3 O 4 particles are promising for supercapacitor applications. [ABSTRACT FROM AUTHOR]

• Hierarchical Co 3 O 4 /rGO nanocomposites are synthesized by a facile one-pot microwave-assisted hydrothermal approach. • The size of Co 3 O 4 nanoparticles is effectively reduced to 8.5 nm by 35 wt% addition of rGO. • Co 3 O 4 /rGO composites exhibit a specific capacitance of 1031 F g−1 at 1 A g−1, and 78% capacitance retention at 10 A g−1. • The approach can be extended to synthesize other TMOs and carbonaceous nanocomposites for superior electrode materials. The composites composed of transition metal oxide and carbonaceous nanomaterials have been regarded as one of the promising electrode materials for high performance supercapacitors. How to develop effective hybridization of two components to deliver synergistic effect on electrochemical performance is a key question to be tackled. Herein, we successfully prepare three-dimensional hierarchical cobalt oxide (Co 3 O 4)/reduced graphene oxide (rGO) composites via a facile, rapid and cost-effective one-pot microwave assisted hydrothermal process. The effects of rGO content on morphology, chemical and crystalline structure, electrode performance are systematically investigated. Interestingly, it is noticed that by changing the addition of graphene oxide (GO), the size of Co 3 O 4 nanoparticles can be effectively controlled, which has a significant effect on the electrochemical properties of electrode materials. The as-prepared Co 3 O 4 /rGO with 23 wt% rGO exhibits an outstanding specific capacitance of 1031 F g−1 at 1 A g−1 and retains 78% of capacitance when current density increased to 10 A g−1, revealing that Co 3 O 4 /rGO composites prepared by this facile process can be an ideal candidate electrode for high performance supercapacitors. [ABSTRACT FROM AUTHOR]

Different morphologies of Co 3 O 4 nanopoarticles formed on nanographitic flakes are synthesized based on the decomposition of cobalt acetate precursor in ethylene glycol at 180 ​°C for 18 ​h by a solvothermal process followed with a heat treatment at the different temperatures of 350, 450, and 550 ​°C. Then, an electrophoretic deposition process is used to form the composite layers on the stainless steel plates. Among those temperatures, the layer prepared at 450 ​°C shows superior morphology and less aggregated nanoparticles, which is consistent with the electrochemical battery experiments. The electrode fabricated at 450 ​°C shows a charge capacity of 428 ​mA/g after 50 cycles at 1 A/g with a total retention of 90% which is higher than the charge capacities of the other electrodes heated at 350 and 550 ​°C. The cycling and rate performance results for the fabricated electrode heated at 450 ​°C manifest the superior distribution of the Co 3 O 4 nanoparticles on the nanographitic flakes. Image 1 [ABSTRACT FROM AUTHOR]