Mn3O4 nanoparticles embedded into graphene nanosheets: Preparation, characterization, and electrochemical properties for supercapacitors

One-Step Hydrothermal Synthesis of Nitrogen-Doped Reduced Graphene Oxide/Hausmannite Manganese Oxide for Symmetric and Asymmetric Pseudocapacitors

In this paper, the pseudocapacitive performance of nitrogen-doped and undoped reduced graphene oxide/tetragonal hausmannite nanohybrids (N-rGO/Mn₃O₄ and rGO/Mn₃O₄) synthesized using a one-pot hydrothermal method is reported. The nanohybrid electrode materials displayed exceptional electrochemical performance relative to their respective individual precursors (i.e., reduced graphene oxide (rGO), nitrogen-doped reduced graphene oxide (N-rGO), and tetragonal hausmannite (Mn₃O₄)) for symmetric pseudocapacitors. Among the two nanohybrids, N-rGO/Mn₃O₄ displayed greater performance with a high specific capacitance of 345 F g^-1 at a current density of 0.1 A g^-1, excellent specific energy of 12.0 Wh kg^-1 (0.1 A g^-1), and a high power density of 22.5 kW kg^-1 (10.0 A g^-1), while rGO/Mn₃O₄ demonstrated a high specific capacitance of 264 F g^-1 (0.1 A g^-1) with specific energy and power densities of 9.2 Wh kg^-1 (0.1 A g^-1) and 23.6 kW kg^-1 (10.0 A g^-1), respectively. Furthermore, the N-rGO/Mn₃O₄ nanohybrid exhibited an impressive pseudocapacitive performance when fabricated in an asymmetric configuration, having a stable potential window of 2.0 V in 1.0 M Na₂SO₄ electrolyte. The nanohybrid showed excellent specific energy and power densities of 34.6 Wh kg^-1 (0.1 A g^-1) and 14.01 kW kg^-1 (10.0 A g^-1), respectively. These promising results provide a good substance for developing novel carbon-based metal oxide electrode materials in pseudocapacitor applications.

Augmenting the electrochemical performance of NiMn2O4 by doping of transition metal ions and compositing with rGO

The transition metal ions (TMIs) such as Co²⁺ and Zn²⁺ doped NiMn₂O₄ (NMO)/rGO nanocomposite synthesized by facile sol-gel method was used for the fabrication of supercapacitor. The presence of metal ions in the nanocomposite was confirmed by X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscope (HR-TEM) mapping techniques. The fabricated electrode showed high specific capacitance of 710 F/g which was 3-fold higher than NMO (254 F/g). The addition of RGO in the nanocomposite increased the cycle stability of TMIs doped NMO significantly from 51 to 91%. In addition, the symmetric supercapacitor (SSC) fabricated using TMIs doped NMO/rGO nanocomposite with 3.5 M KOH as an electrolyte delivered a maximum energy density of 43 Wh/kg and power density of 10 kW/kg. Furthermore, the SSC device retained 90% of capacitance retention over 10,000 cycles with coulombic efficiency of 99% at 5 A/g. These result suggested that the TMIs doped NMO/rGO nanocomposite electrode is a promising material for high-energy supercapacitors.

Frontier performance of in situ formed α-MnO2 dispersed over functionalized multi-walled carbon nanotubes covalently anchored to a graphene oxide nanosheet framework as supercapacitor materials

α-MnO₂ has been recognized as a potential material for supercapacitor applications because of its abundance, cost-effectiveness, environmental-benign nature and high theoretical specific capacitance (C_sp) of 1370 F g⁻¹. In this study, we succeeded for the first time to achieve the theoretical C_sp with 3D multi-walled carbon nanotubes (MWCNTs) horizontally dispersed on 2D graphene oxide (GO) nanosheet framework-supported MnO₂ ternary nanocomposites synthesized by a simple precipitation method. The in situ formation of α-MnO₂ and GO, and the growth of 3D MWCNT/GO framework took place simultaneously in a strong acidic suspension containing functionalized-MWCNTs, graphite, NaNO₃ and KMnO₄. Characterizations of the composites synthesized by varying % wt MWCNTs were performed with state-of-the-art techniques. These composites were characterized to be semi-crystalline and mesoporous in nature, and the scrupulous analyses of field emission scanning electron microscopic images showed MnO₂ nano-flower distributed over 3D MWCNTs dispersed-on-GO-nanosheet frameworks. These composites deposited on a graphite electrode exhibited an ideal supercapacitive behavior in an Na₂SO₄ solution measured via cyclic voltammetry and chronopotentiometry. Optimum contents of MnO₂ and MWCNTs in the composites showed a maximum C_sp of 1380 F g⁻¹ with satisfactory energy and power densities compared in the Ragone plot. An ascending trend of C_sp against the charge–discharge cycle number studied for 700 cycles was noticed. Well-dispersion of α-MnO₂ nanoparticles throughout 3D MWCNTs covalently-anchored to the GO nanosheet framework is discussed to aid in achieving the frontier C_sp of MnO₂.

Achieving the milestone of theoretical capacitance of α-MnO₂ dispersed over 3D multi-walled carbon nanotubes anchored to a graphene oxide nanosheet framework.

Current Research of Graphene-Based Nanocomposites and Their Application for Supercapacitors

This review acmes the latest developments of composites of metal oxides/sulfide comprising of graphene and its analogues as electrode materials in the construction of the next generation of supercapacitors (SCs). SCs have become an indispensable device of energy-storage modes. A prompt increase in the number of scientific accomplishments in this field, including publications, patents, and device fabrication, has evidenced the immense attention they have attracted from scientific communities. These efforts have resulted in rapid advancements in the field of SCs, focusing on the development of electrode materials with features of high performance, economic viability, and robustness. It has been demonstrated that carbon-based electrode materials mixed with metal oxides and sulfoxides can perform extremely well in terms of energy density, durability, and exceptional cyclic stability. Herein, the state-of-the-art technologies relevant to the fabrication, characterization, and property assessment of graphene-based SCs are discussed in detail, especially for the composite forms when mixing with metal sulfide, metal oxides, metal foams, and nanohybrids. Effective synthetic methodologies for the nanocomposite fabrications via intercalation, coating, wrapping, and covalent interactions will be reviewed. We will first introduce some fundamental aspects of SCs, and briefly highlight the impact of graphene-based nanostructures on the basic principle of SCs, and then the recent progress in graphene-based electrodes, electrolytes, and all-solid-state SCs will be covered. The important surface properties of the metal oxides/sulfides electrode materials (nickel oxide, nickel sulfide, molybdenum oxide, ruthenium oxides, stannous oxide, nickel-cobalt sulfide manganese oxides, multiferroic materials like BaMnF, core-shell materials, etc.) will be described in each section as per requirement. Finally, we will show that composites of graphene-based electrodes are promising for the construction of the next generation of high performance, robust SCs that hold the prospects for practical applications.

Graphene nanosheets as reinforcement and cell-instructive material in soft tissue scaffolds

Mechanical strength of polymeric scaffolds deteriorates quickly in the physiological mileu. This can be minimized by reinforcing the polymeric matrix with graphene, a planar two-dimensional material with unique physicochemical and biological properties. Association between the sheet and polymer chains offers a range of porosity commensurate with tissue requirements. Besides, studies suggest that corrugated structure of graphene offers desirable bio-mechanical cues for tissue regeneration. This review covers three important aspects of graphene-polymer composites, (a) the opportunity on reinforcing the polymer matrix with graphene, (b) challenges associated with limited aqueous processability of graphene, and (c) physiological signaling in the presence of graphene. Among numerous graphene materials, our discussion is limited to graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets. Challenges associated with limited dispersity of hydrophobic sheets within the polymeric matrix have been discussed at molecular level.

Nanostructured manganese oxides electrode with ultra-long lifetime for electrochemical capacitors

We describe the instantaneous fabrication of a highly porous three-dimensional (3D) nanostructured manganese oxides-reduced graphitic oxide (MnO_x-rGO) electrode by using a pulse-photonic processing technique. Such nanostructures facilitate the movement of ions/electrons and offer an extremely high surface area for the electrode/electrolyte interaction. The electrochemical performance was investigated by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) with 1 M KOH as the electrolyte. The as-prepared thin film electrode exhibits excellent electrochemical performance and an ultra-long lifetime by retaining 90% of the initial capacitance even after 100 000 GCD cycles at constant areal current density of 0.4 mA cm⁻². We attribute this excellent lifetime performance to the conductive reduced graphitic oxide, synergistic effects of carbon composite and the metal oxides, and the unique porous nanostructure. Such highly porous morphology also enhances the structural stability of the electrode by buffering the volume changes during the redox processes.

We describe the instantaneous fabrication of a highly porous three-dimensional (3D) nanostructured manganese oxides-reduced graphitic oxide (MnO_x-rGO) electrode by using a pulse-photonic processing technique.

Europium oxide nanorod-reduced graphene oxide nanocomposites towards supercapacitors

Fast charge/discharge cycles are necessary for supercapacitors applied in vehicles including, buses, cars and elevators. Nanocomposites of graphene oxide with lanthanide oxides show better supercapacitive performance in comparison to any of them alone. Herein, Eu₂O₃ nanorods (EuNRs) were prepared through the hydrothermal method and anchored onto the surface of reduced graphene oxide (RGO) by utilizing a sonochemical procedure (in an ultrasonic bath) through a self-assembly methodology. The morphologies of EuNRs and EuNR-RGO were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and IR spectroscopy. Then, we used EuNRs and EuNR-RGO as electrode materials to investigate their supercapacitive behavior using cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques. In a 3.0 M KCl electrolyte and with a scan rate of 2 mV s⁻¹, EuNR-RGO exhibited a specific capacity of 403 F g⁻¹. Galvanostatic charge–discharge experiments demonstrated a specific capacity of 345.9 F g⁻¹ at a current density of 2 A g⁻¹. The synergy between RGO's flexibility and EuNR's high charge mobility caused these noticeable properties.

Fast charge/discharge cycles are necessary for supercapacitors applied in vehicles including, buses, cars and elevators.

Manganese oxide synthesized from spent Zn-C battery for supercapacitor electrode application

Manganese oxide (Mn₃O₄) nanomaterials have promising potential to be used as supercapacitor electrode materials due to its high energy storage performance and environmental compatibility. Besides, every year huge volume of waste batteries including Zn-C battery ends up in landfill, which aggravates the burden of waste disposal in landfill and creates environmental and health threat. Thus, transformation of waste battery back into energy application, is of great significance for sustainable strategies. Compared with complex chemical routes which mostly apply toxic acids to recover materials from Zn-C battery, this study establishes the recovery of Mn₃O₄ particles via thermal route within 900 °C under controlled atmosphere. Synthesized Mn₃O₄ were confirmed by XRD, EDS, FTIR, XPS and Raman analysis and FESEM micrographs confirmed the coexistence of spherical and cubic Mn₃O₄ particles. Mn₃O₄ electrode derived from waste Zn-C battery demonstrate compatible electrochemical performance with standard materials and conventional synthesis techniques. Mn₃O₄ electrode exhibited highest capacitance value of 125 Fg⁻¹ at 5 mVs⁻¹ scan rate. The stability of the electrode showed good retention in discharge and charge capacity by about 80% after 2100 cycles. This study demonstrates that waste Zn-C battery can be further utilized for energy storage application, providing sustainable and economic benefits.

Controllable synthesis and electrochemical capacitor performance of MOF-derived MnOx/N-doped carbon/MnO2 composites

Different amount of carbon and nitrogen, for MOF-derived nitrogen-doped carbon/Mn₃O₄ composites, can result in the discrepancies of synergistic effect which plays an important role in final electrochemical performance.

The enhanced photo-thermal therapy of Surface improved photoactive cadmium sulfide (CdS) quantum dots entrenched graphene oxide nanoflakes in tumor treatment

Cancer is one of the death causing disease is always being a public health concern due to its rapid increase in the world population. Hyperthermal therapy is an anticancer treatment mutually given with chemotherapy. In the present study, CdS/rGO nanocomposites were synthesized using simple and scalable solvothermal method and applied as an efficient material in anticancer treatment. The prepared nanocomposites were characterized from physicochemical characterization techniques. The surface morphology and the crystallographic details were obtained from TEM and XRD analyses respectively. The elemental composition was confirmed from XPS spectra. The phase purity and the functional group analysis were done using Raman and FTIR spectroscopies respectively. The morphological analysis has been displayed the spherical shaped CdS nanoparticles that are firmly attached on the rGO thin sheet matrix further confirmed the formation of CdS/rGO nanoflakes. The live-dead assay method (cancerous and normal cell lines) cytocompatibility study displayed the cell survival of the CdS/rGO nanomaterials exhibited that above 95%, which means materials highly appropriate for the cancer therapy. The temperature profile of the CdS/rGO nanoflakes has enhanced effectively under the NIR absorption property of CdS coated rGO nanoflakes, which influenced to the cancer cell death. The results shown the anticancer activity of the proposed nanocomposites could open a new avenue in biomedicine research and utilized as an efficient materials for practical applications.

Dynamics of GeSbTe phase-change nanoparticles deposited on graphene

Phase-change Ge₂Sb₂Te₅ nanoparticles (NPs), that are promising for next-generation phase-change memory and other emerging optoelectronic applications, have been deposited on graphene support layers and analyzed using advanced transmission electron microscopy techniques allowing high quality atomic resolution imaging at accelerating voltages as low as 40 kV. The deposition results in about three times higher NP coverage on suspended graphene than on graphene containing an amorphous background support. We attribute this to the variation in surface energy of suspended and supported graphene, indicating that the former harvests NPs more effectively. Hydrocarbon contamination on the graphene profoundly enhances the mobility of the NP atoms and after prolonged (weeks) exposure to air resulted in more severe oxidation and spreading of NPs on the suspended graphene than on supported graphene because the network of hydrocarbons develops more extensively on the suspended rather than on the supported graphene. Due to this oxidation, GeO _x shells are formed out of NPs having a uniform composition initially. The present work provides new insights into the structure and stability of phase-change NPs, graphene and their combinations.

On the Solvation Behavior of Graphene Oxide in Ethylene Glycol/Water Mixtures

The self-association and solvation pattern of graphene oxide (GO) in water, ethylene glycol (EG), and their mixtures were analyzed by means of UV/Vis spectrophotometry. A careful analysis of the absorbance dependencies vs. the GO concentration shows that self-association of the GO sheets in EG occurs at higher concentration compared to that in water. It was established that depending on the mixed solvent composition, two different types of the GO solvates are formed. The results of quantum chemical calculations allow one to suggest that in the water-rich compositions, the GO oxygen-containing groups are in direct contact with water molecules while in the glycol-rich media the EG molecules fully substitute water in the GO's first solvation layer.

Reduced graphene oxide-mediated synthesis of Mn3O4 nanomaterials for an asymmetric supercapacitor cell

Herein, Mn₃O₄/reduced graphene oxide composites are prepared via a facile solution-phase method for supercapacitor application. Transmission electron microscopy results reveal the uniform distribution of Mn₃O₄ nanoparticles on graphene layers. The morphology of the Mn₃O₄ nanomaterial is changed by introducing the reduced graphene oxide during the preparation process. An asymmetric supercapacitor cell based on the Mn₃O₄/reduced graphene oxide composite with the weight ratio of 1 : 1 exhibits relatively superior charge storage properties with higher specific capacitance and larger energy density compared with those of pure reduced graphene oxide or Mn₃O₄. More importantly, the long-term stability of the composite with more than 90.3% capacitance retention after 10 000 cycles can ensure that the product is widely applied in energy storage devices.

The existence presence of rGO can affect the morphology of an Mn₃O₄/rGO composite, and the asymmetric supercapacitor cell created with this composite exhibits good capacitive performance.

Uniformly Dispersed ZnFe2O4 Nanoparticles on Nitrogen-Modified Graphene for High-Performance Supercapacitor as Electrode

A facile strategy has been adopted for the preparation of ZnFe₂O₄/NRG composite by anchoring ultrasmall ZnFe₂O₄ nanoparticles on nitrogen-doped reduced graphene (denoted as NRG) for high-performance supercapacitor electrode. Remarkably, the growth of ZnFe₂O₄ nanocrystals, the reduction of graphitic oxide and the doping of nitrogen to graphene have been simultaneously achieved in one process. It is found that the NRG employed as substrate can not only control the formation of nano-sized ZnFe₂O₄, but also guarantee the high dispersion without any agglomeration. Benefiting from this novel combination and construction, the hybrid material has large surface area which can provide high exposure of active sites for easy access of electrolyte and fast electron transport. When served as supercapacitor electrode, the ZnFe₂O₄/NRG composite exhibits a favorable specific capacitance of 244 F/g at 0.5 A/g within the potential range from −1 to 0 V, desirable rate stability (retain 131.5 F/g at 10 A/g) and an admirable cycling durability of 83.8% at a scan rate of 100 mV/s after 5000 cycles. When employed as symmetric supercapacitor, the device demonstrates favorable performance. These satisfactory properties of the ZnFe₂O₄/NRG composite can make it be of great promise in the supercapacitor application.

2-Dimensional graphene as a route for emergence of additional dimension nanomaterials

Dimension has a different and impactful significance in the field of innovation, research and technologies. Starting from one-dimension, now, we all are moving towards 3-D visuals and try to do the things in this dimension. However, we still have some very innovative and widely applicable nanomaterials, which have tremendous potential in the form of 2-D only i.e. graphene. In this review, we have tried to incorporate the reported pathways used so far for modification of 2-D graphene sheets to make is three-dimensional. The modified graphene been applied in many fields like supercapacitors, sensors, catalysis, energy storage devices and many more. In addition, we have also incorporated the conversion of 2-D graphene to their various other dimensions like zero-, one- or three-dimensional nanostructures.

Nitrogen-modified biomass-derived cheese-like porous carbon for electric double layer capacitors

Lignin, an abundant biomass constituent in nature, was modified by pyrrole to produce nitrogen-doped porous carbon.

Sonochemical preparation of a ytterbium oxide/reduced graphene oxide nanocomposite for supercapacitors with enhanced capacitive performance

Decoration of graphene with different nanostructures can result in fundamental advancements in versatile technologies, especially in the fast growing fields of catalysts, sensors and energy storage.

Facile and creative design of hierarchical vanadium oxides@graphene nanosheet patterns

We make up the vanadium oxides@graphene nanosheets multi-layer structure cathode materials for sodium batteries by creatively using spin coating method. These multi-layer structure cathode materials had exhibited good stability and high capacity.

Morphology-tunable ultrafine metal oxide nanostructures uniformly grown on graphene and their applications in the photo-Fenton system

Hybrid nanostructures of low-dimensional metal oxide (MO) semiconductors based on two-dimensional (2D) graphene nanosheets have been considered as one of the most promising nanomaterials for an extensive variety of applications. Unfortunately, it is still challenging to rationally design and fabricate MO/graphene hybrids with highly controllable nanostructures and desirable properties, which are of paramount importance for practical applications. Here, we report a novel, facile and "green" glycerol-mediated self-assembly method, using α-Fe2O3 semiconductor as an illustrative example, for the controlled growth of MO with a well-defined nanostructure on 2D graphene nanosheets. Based on this new method, we first demonstrate the ability to exquisitely tune the α-Fe2O3 nanostructure from zero-dimensional quantum dots (∼3.2 nm) to one-dimensional mesoporous nanorods, and eventually to 2D mesoporous nanosheets over the entire surface of graphene nanosheets. A possible formation mechanism has been proposed based on the systematic investigation of the morphological evolution and growth processes of α-Fe2O3 on graphene. The as-synthesized samples exhibit excellent performance for the photo-Fenton treatment of polluted water at neutral pH under visible light irradiation. Moreover, TiO2 and Fe3O4 quantum dots (∼5.2 and 3.3 nm, respectively) ultradispersed on graphene are also successfully synthesized by this method, demonstrating its versatility for the rational fabrication of novel MO/graphene hybrids with huge potential applications.

High nitrogen-doped carbon/Mn3O4 hybrids synthesized from nitrogen-rich coordination polymer particles as supercapacitor electrodes

High nitrogen-doped carbon/Mn3O4 composites were synthesized by annealing nitrogen-rich Mn-based coordination polymer particles, and investigated by electron microscopy, X-ray diffraction, and electrochemical experiments. To assess the performance of high nitrogen-doped hybrids as electrode materials in supercapacitors, cyclic voltammetry and galvanostatic charging-discharging measurements are performed. High nitrogen-doped carbon/Mn3O4 composites are charged and discharged faster and have higher capacitance than carbon/Mn3O4 nanostructures with low nitrogen amounts and other reported ones. The capacitance of the high nitrogen-doped carbon/Mn3O4 is 94% retained after 1000 cycles at a constant current. These improvements can be attributed to the nitrogen-doped carbon matrix, which promotes fast Faradaic charging and discharging of the Mn3O4 motifs. The nitrogen-doped carbon/Mn3O4 composites could be a promising candidate material for a high-capacity, low-cost, and environmentally friendly electrode for supercapacitors.

Superior cycle performance and high reversible capacity of SnO2/graphene composite as an anode material for lithium-ion batteries

SnO2/graphene composite with superior cycle performance and high reversible capacity was prepared by a one-step microwave-hydrothermal method using a microwave reaction system. The SnO2/graphene composite was characterized by X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared spectroscopy, Raman spectroscopy, scanning electron microscope, X-ray photoelectron spectroscopy, transmission electron microscopy and high resolution transmission electron microscopy. The size of SnO2 grains deposited on graphene sheets is less than 3.5 nm. The SnO2/graphene composite exhibits high capacity and excellent electrochemical performance in lithium-ion batteries. The first discharge and charge capacities at a current density of 100 mA g(-1) are 2213 and 1402 mA h g(-1) with coulomb efficiencies of 63.35%. The discharge specific capacities remains 1359, 1228, 1090 and 1005 mA h g(-1) after 100 cycles at current densities of 100, 300, 500 and 700 mA g(-1), respectively. Even at a high current density of 1000 mA g(-1), the first discharge and charge capacities are 1502 and 876 mA h g(-1), and the discharge specific capacities remains 1057 and 677 mA h g(-1) after 420 and 1000 cycles, respectively. The SnO2/graphene composite demonstrates a stable cycle performance and high reversible capacity for lithium storage.

Chemical versus electrochemical synthesis of carbon nano-onion/polypyrrole composites for supercapacitor electrodes

The development of high-surface-area carbon electrodes with a defined pore size distribution and the incorporation of pseudo-active materials to optimize the overall capacitance and conductivity without destroying the stability are at present important research areas. Composite electrodes of carbon nano-onions (CNOs) and polypyrrole (Ppy) were fabricated to improve the specific capacitance of a supercapacitor. The carbon nanostructures were uniformly coated with Ppy by chemical polymerization or by electrochemical potentiostatic deposition to form homogenous composites or bilayers. The materials were characterized by transmission- and scanning electron microscopy, differential thermogravimetric analyses, FTIR spectroscopy, piezoelectric microgravimetry, and cyclic voltammetry. The composites show higher mechanical and electrochemical stabilities, with high specific capacitances of up to about 800 F g(-1) for the CNOs/SDS/Ppy composites (chemical synthesis) and about 1300 F g(-1) for the CNOs/Ppy bilayer (electrochemical deposition).

Nanosheet-structured boron nitride spheres with a versatile adsorption capacity for water cleaning

Here, we report the synthesis of nanosheet-structured boron nitride spheres (NSBNSs) by a catalyzing thermal evaporation method from solid B powders. The NSBNSs consist of radially oriented ultrathin nanosheets with the sheet edges oriented on the surface. Formation of this unique structure occurs only at a certain reaction temperature. The diameter from 4 μm to 700 nm and the nanosheet thickness from 9.1 to 3.1 nm of the NSBNSs can be well-controlled by appropriately changing the mass ratio of boron powders and catalyst. The NSBNSs possess versatile adsorption capacity, exhibiting excellent adsorption performance for oil, dyes, and heavy metal ions from water. The oil uptake reaches 7.8 times its own weight. The adsorption capacities for malachite green and methylene blue are 324 and 233 mg/g, while those for Cu(2+), Pb(2+), and Cd(2+) are 678.7, 536.7, and 107.0 mg/g, respectively. The adsorption capacities of the NSBNSs for Cu(2+) and Pb(2+) are higher or much higher than those of the adsorbents reported previously. These results demonstrate the great potential of NSBNSs for water treatment and cleaning.

Microwave-assisted in situ synthesis of reduced graphene oxide/Mn3O4 composites for supercapacitor applications

Rationally designed reduced graphene oxide/Mn₃O₄ (GM) was achieved and GM showed long-stability capacitance after 5000 cycles at 1 A g⁻¹.

A high performance supercapacitor based on a ceria/graphene nanocomposite synthesized by a facile sonochemical method

In this work, we have developed a novel nanocomposite material of ceria (CeO₂)–reduced graphene oxide (RGO) by a sonochemical route for application as a symmetric supercapacitor.

A novel hydrothermal synthesis and characterisation of porous Mn3O4 for supercapacitors with high rate capability

Porous nanostructured Mn₃O₄ particles were successfully synthesized by a novel hydrothermal method via adding the surfactant hexadecyltrimethylammonium bromide (CTAB) and exhibit good rate capability.

The simultaneous determination of omethoate and dichlorvos pesticides in grain samples using a palladium and graphene composite modified glassy carbon electrode

An electrochemical sensor based on a palladium (Pd) and graphene (Gr) composite modified GCE was fabricated, characterised and used for the simultaneous determination of OMT and DCV in grain samples.

Fibrous porous silica microspheres decorated with Mn3O4 for effective removal of methyl orange from aqueous solution

In this work, trimanganese tetraoxide (Mn₃O₄) functionalized fibrous porous silica microspheres (KCC-1) with well-dispersed and excellent adsorption capacities were successfully synthesized by a simple and mild method for the first time.

Synthesis of shape-controlled NiO–graphene nanocomposites with enhanced supercapacitive properties

The flowerlike and polyhedral NiO–graphene composites show high supercapacitive performances which were synthesized using a facile hydrothermal method.

Synthesis of micro/nano-structured Mn3O4 for supercapacitor electrode with excellent rate performance

Micro/nano-structured Mn₃O₄ with an open three-dimensional flower-like morphology were fabricated by a facile solvothermal approach using hexadecyltrimethylammonium bromide as a surfactant and CH₃CH₂OH as a solvent.

One-step synthesis of Pt-reduced graphene oxide composites based on high-energy radiation technique

In this paper, we introduce a novel 60Co-ray-irradiation-based one-step synthesis method of Pt-reduced graphene oxide composites (Pt-RGO) in acid aqueous solution. The compositional distribution of the particles in the samples was characterized by transmission electron microscopy. The structure and composition of the nanocomposite has been determined with a scanning electron microscope (SEM) equipped with an energy dispersion X-ray (EDS) analyzer. Surface enhanced Raman scattering (SERS) of graphene deposited by the Pt nanoparticles were investigated with the 514.5 nm excitation. It was found that small-sized and highly-dispersed Pt nanoparticles could easily grow on the RGO surface under acidic conditions. In addition, the obtained homogeneous dispersions exhibit long-term stability, which will facilitate the production of homogeneous composites.