Manganese Dioxide Nanowires of Tunable Dimensions Synthesized via a Facile Hydrothermal Route

Manganese dioxide (MnO2) nanowires of tunable dimensions were successfully synthesized via the facile water-bathing hydrothermal route. Homogeneous solution mixtures of KMnO4 and MnSO4 of varying compositions were being aged in a thermostated water bath under controlled conditions. The dimensional aspect ratios of MnO2 nanowires formed were readily modulated by varying synthesis parameters such as the initial concentration of chemical precursors, reaction temperature, and aging duration. At fixed initial precursor concentrations, the mean diameter of MnO2 nanowires decreased slightly from 57 nm to 53 nm with increased reaction temperature from 60°C to 90°C. The mean diameter of MnO2 nanowires decreased linearly within the range of 104 nm and 35 nm as the initial concentration of both precursors was increased in turn within the range of 10 mmol and 40 mmol at fixed aging temperature and duration. Upon aging for 2 to 24 hours at 80°C, the mean diameter and length of MnO2 nanowires were observed to vary within the range of 33–55 nm and 0.69–2.68 μm, respectively, which corresponded to the dimensional aspect ratio range of 21 to 49. Henceforth, MnO2 nanowires of tunable dimensions could be synthesized through optimally controlled synthesis parameters

Controlled Synthesis of Manganese Dioxide Nanostructures via a Facile Hydrothermal Route

Manganese dioxide nanostructures with controllable morphological structures and crystalline phases were synthesized via a facile hydrothermal route at low temperatures without using any templates or surfactants. Both the aging duration and aging temperatures were the main synthesis parameters used to influence and control the rate of morphological and structural evolution of MnO2 nanostructures. MnO2 nanostructures comprise of spherical nanoparticulate agglomerates and highly amorphous in nature were formed at lower temperature and/or short aging duration. In contrast, MnO2 nanostructures of sea-urchin-like and nanorods-like morphologies and nanocrystalline in nature were prepared at the combined higher aging temperatures and longer aging durations. These nanostructures underwent notable phase transformation from δ-MnO2 to α-MnO2 upon prolonged hydrothermal aging duration and exhibited accelerated rate of phase transformation at higher aging temperature

Tetrapropylammonium-manganese oxide/polypyrrole hybrid nanocomposite thin films as novel electrode materials for supercapacitors

Tetrapropylammonium-manganese oxide/polypyrrole (TPA-MO/Ppy) hybrid nanocomposite with molar ratios of TPA-MO/Ppy 4:1, 2:1 and 1:1 were successfully prepared by a combination of in situ polymerization and the sol–gel process. The microstructure of hybrid nanocomposite thin film samples was observed to be significantly affected by synthesis parameters, most notably the molar ratio of reactants and post-synthesis calcination temperature. Samples with higher pyrrole contents appeared to possess higher specific surface areas, which ranged from 132 to 281m2 g−1. SEM micrographs indicated that all nanocomposite thin films were highly fibrous and porous in nature. Optimum doping of manganese oxide with conducting polypyrrole had led to the formation of novel nanocomposite with nanofibrillar structures which consisted of interconnected manganese oxide and polypyrrole nanoclusters. Optimized nanocomposite films showed higher charge capacities which could be attributed to enhanced material utilization as a result of optimized microstuctural parameters in particular, specific surface area

Nanostructured Multilayer Composite Films of Manganese Dioxide/Nickel/Copper Sulfide Deposited on Polyethylene Terephthalate Supporting Substrate

Nanostructured multilayer manganese dioxide/nickel/copper sulfide (MnO2/Ni/CuS) composite films were successfully deposited onto supporting polyethylene terephthalate (PET) substrate through the sequential deposition of CuS, Ni, and MnO2 thin films by chemical bath deposition, electrodeposition, and horizontal submersion deposition techniques, respectively. Deposition of each thin-film layer was optimized by varying deposition parameters and conditions associated with specific deposition technique. Both CuS and Ni thin films were optimized for their electrical conductivity whereas MnO2 thin film was optimized for its microstructure and charge capacity. The electrochemical properties of nanostructured multilayer MnO2/Ni/CuS composite films were evaluated by cyclic voltammetry as electrode materials of an electrochemical capacitor prototype in a dual-planar device configuration. Cyclic voltammogram in mild Na2SO4 aqueous electrolyte exhibited a featureless and almost rectangular shape which was indicative of the ideal capacitive behavior and high cycling reversibility of the electrochemical capacitor prototype. Nanostructured multilayer MnO2/Ni/CuS composite films on supporting polyethylene terephthalate (PET) substrate could potentially be utilized as electrode materials for the fabrication of high performance electrochemical capacitors

Starch Acetate Nanoparticles as Controlled Release Nanocarriers for Piperine

This paper aims to synthesize starch acetate nanoparticles for controlled release of piperine. Starch acetate is synthesized by chemically modified sago starch with acetylation reaction. Starch acetate nanoparticles with mean particle sizes of 110 nm are obtained by controlled precipitation through drop-wise addition of dissolved starch acetate solution into excess absolute ethanol. Piperine is loaded onto starch acetate nanoparticles and native starch nanoparticles via the in situ nanoprecipitation process. Starch acetate nanoparticles exhibit higher piperine loading capacity as compared to native starch nanoparticles with the maximum loading capacity of 0.46 and 0.33 mg mg–1, respectively. Piperine is observed to release from starch acetate nanoparticles in a slow and sustained manner at pH 1.2 for 24 h. In contrast, piperine is observed to fully release from native starch nanoparticles after 16 h

Electrochemical Reduction and Deposition of Reduced Graphene Oxide/Manganese Oxide Composite for Supercapacitor Applications via Pulse-Chronoamperometry

The reduced graphene oxide/manganese oxide composite was deposited on the nickel current collector using the Pulse-Chronoamperometry method in a mixture of graphene oxide dispersion and manganese acetate as the precursor. The graphene oxide (GO) was electrochemically reduced to reduced graphene oxide (rGO) and deposited with manganese oxide (MnOx) at the same time. The effects of manganese acetate (Mn(Ac)2) concentration, deposition temperature, voltage and time on the specific capacitance of rGO/MnOx electrode were investigated. The electrochemical properties were characterized using galvanostatic charge-discharge and cyclic voltammetry. The effects of electrochemical reduction and deposition parameters on the specific capacitance of rGO/MnOx electrode were studied using Central Composite Design methodology and a 2 factors interaction model equation was evaluated. The rGO/MnOx electrode synthesized using 0.2 M of Mn(Ac)2, at 70 °C and -1.0 V versus Saturated Calomel Electrode (SCE) with a total deposition time of 800s exhibited a specific capacitance of 665 F/g was obtained at the current density of 5 A/g. The high specific capacitance of rGO/MnOx electrode showed its potential application for the fabrication of supercapacitors. This study provides an environmental friendly, time effective and costs efficiency way to reduce graphene oxide and to deposit the rGO/MnOx composite for electrochemical energy storage application

Size controlled fabrication of cellulose nanoparticles for drug delivery applications

Spherically shaped cellulose nanoparticles with average particle diameter range between 70 and 365 nm were fabricated from cotton fibers by a simple nanoprecipitation method. The average particle diameter of cellulose nanoparticles could be precisely controlled by modulating the synthesis conditions such as cellulose solution concentration and volume ratio of solvent/non-solvent. Methylene blue (MB) as a model hydrophilic drug was loaded onto cellulose nanoparticles via the in-situ nanoprecipitation process. The loading efficiency and release profile of MB were observed to be affected by the average particle diameter of cellulose nanoparticles. © 201

Catalytic Performance of Copper-Manganese Supported on Activated Carbon Synthesized by Deposition-Precipitation Method

CuMnx/activated carbon (AC, x = 0.1, 0.2, 0.5 and 1) nanoparticles were prepared by deposition-precipitation method. The catalytic performance of CuMnx/AC catalysts were studied for the oxidation of benzyl alcohol to benzaldehyde. The molar ratio of Mn plays an important role in the catalytic performances. The optimum amount of Mn is 0.1 with the highest benzyl alcohol conversion of 63 %

Hydroxypropyl Starch Nanoparticles as Controlled Release Nanocarriers for Piperine

Hydroxypropyl starch was synthesized by modified sago starch with hydroxypropylation reaction. Hydroxypropyl starch nanoparticles with mean particle sizes of 110 nm are obtained by controlled precipitation through the drop-wise addition of dissolved hydroxypropyl starch solution into excess absolute ethanol. Piperine was loaded onto hydroxypropyl starch nanoparticles and native starch nanoparticles via the in-situ nanoprecipitation process. Hydroxypropyl starch nanoparticles exhibited higher piperine loading capacity as compared to native starch nanoparticles with the maximum loading capacity of 0.46 and 0.33 mg.mg-1, respectively. Piperine was release from hydroxypropyl starch nanoparticles in a slow and sustained manner at pH 1.2 over the period of 24 hours. Whereas piperine was completely released from native starch nanoparticles within 16 hours