We present synthesis, structure and magnetic properties of structurally well-ordered single-crystalline b-MnO2 nanorods of 50–100 nm diameter and several lm length. Thorough structural characterization shows that the basic b-MnO2 material is covered by a thin surface layer (~2.5 nm) of a-Mn2O3 phase with a reduced Mn valence that adds its own magnetic signal to the total magnetization of the b-...

Particle sizes of manganese oxide (β-MnO2) powders were modified by using a mortar and pestle ground method for period of times that varied between 15-60 min. Particle size versus ground time clearly shows the existence of a size-induced regime transition (i.e., regime I and II). Thermoelectric properties of β-MnO2 powders as a function of electrical resistance in the range of R P  = 10 - 80Ω w...

In this article, we report a newly devised composite electrode for electrochemical capacitors, by depositing manganese dioxide (MnO2) on the surface of carbon nanotubes via a spontaneous redox reaction. X-ray diffraction and transmission electron microscopic studies demonstrated a homogeneous coating of layered MnO2 on the surface of the carbon nanotubes. The MWNT@MnO2 composite electrode displ...

We report on a novel drug carrier which is based on the combination of magnetic and upconversion (UC) emission of Fe3O4@SiO2/NaYF4:Yb, Er (MSU) hybrids modified with MnO2 nanosheets (MSU/MnO2). The MSU hybrids were fabricated by covalently linking amino-modified Fe3O4@SiO2 particles with carboxyl-functionalized NaYF4:Yb, Er particles. The Fe3O4 core and the NaYF4:Yb, Er shell functioned success...

The use of lightweight and easily-fabricated MnO2/carbon nanotube (CNT)-based flexible networks as binder-free electrodes and a polyvinyl alcohol/H2SO4 electrolyte for the formation of stretchable solid-state supercapacitors was examined. The active electrodes were fabricated from 3D honeycomb porous MnO2 assembled from cross-walled and interconnected sheet-architectural MnO2 on CNT-based plast...

A simple and scalable method has been developed to fabricate nanostructured MnO2-carbon nanotube (CNT)-sponge hybrid electrodes. A novel supercapacitor, henceforth referred to as "sponge supercapacitor", has been fabricated using these hybrid electrodes with remarkable performance. A specific capacitance of 1,230 F/g (based on the mass of MnO2) can be reached. Capacitors based on CNT-sponge sub...

A DNA-assisted assembly approach is developed to fabricate a capacitor-type electrode material, DNA-functionalized carbon nanotubes (CNTs@DNA), and a battery-type electrode material, DNA@CNTs-bridged MnO2 spheres (CNTs@DNA-MnO2), for asymmetric supercapacitors. An energy density of 11.6 W h kg(-1) is achieved at a power density of 185.5 W kg(-1) with a high MnO2 mass loading of 4.2 mg cm(-2). I...

Models of MnO2 nanoparticles, with full atomistic detail, have been generated using a simulated amorphization and recrystallization strategy. In particular, a 25,000-atom "cube" of MnO2 was amorphized (tension-induced) under molecular dynamics (MD). Long-duration MD, applied to this system, results in the sudden evolution of a small crystalline region of pyrolusite-structured MnO2, which acts a...

MnO2 materials are prepared through a hydrothermal process. Sn-doping and composite graphene are both achieved simultaneously during the hydrothermal reaction then obtain the electrode materials of supercapacitors. Morphology, structure and electrochemical properties of the samples are evaluated by X-ray diffraction(XRD), scanning electron microscopy (SEM), and electrochemical work station. The...

Porous nanotubes comprised of MnO2 nanosheets were fabricated with a one-pot hydrothermal method using polycarbonate membrane as the template. The diameter and thickness of nanotubes can be controlled by choice of the membrane pore size and the chemistry. The porous MnO2 nanotubes were used as a supercapacitor electrode. The specific capacitance in a three-electrode system was 365 F g(-1) at a ...