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In this work, manganese oxide nanoparticles were radiolytically synthesized in the presence or absence of diethylaminoethyl-dextran hydrochloride (DEAE-dextran). Deoxygenated potassium permanganate (KMnO 4 ) alkaline aqueous suspensions were used as a precursor. The dose rate was~32 kGy h −1 and the absorbed doses were 100 and 200 kGy. The XRD patterns showed broad peaks indicating the low crystallinity and/or amorphous character of synthesized manganese oxides samples. The radiolytically synthesized samples in the presence of DEAE-dextran contained a mixture of phases, namely Mn 2 O 3 , Mn 3 O 4 and an amorphous phase. The samples radiolytically synthesized with no added polymer consist of K 0.27 MnO 2 ۰ 0.54 H 2 O and Mn 3 O 4 (hausmannite). The volume average domain size of hausmannite was estimated to~45 nm using Scherrer equation and Williamson-Hall plots. The hydrodynamic diameters and zeta potential of the samples were measured. The pore radius distributions and pore volume of the obtained manganese oxides were determined by N 2 adsorption-desorption measurements. The synthesized manganese oxide samples were applied for decolorization of methylene blue (MB) aqueous solutions at pH = 2. The MB concentrations in the supernatant solutions were determined through the measurements of the UV-Vis absorbance intensities at a wavelength of 663 nm. The radiolytically synthesized Mn 3 O 4 NPs in the absence of DEAE-dextran polymer (zeta potential of −39.4 mV, BET surface area of 234 m 2 g −1 and pore volume of 1.52 cm 3 g −1 ) showed the highest MB decolorization effect.

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Commercial micrometer silicon (Si) powder was investigated as a potential anode material for lithium ion (Li-ion) batteries. The characterization of this powder showed the mean particle size of approx.75.2 nm, BET surface area of 10.6 m2/g and average pore size of 0.56 nm. Its band gap was estimated to 1.35 eV as determined using UV-Vis diffuse reflectance spectra. In order to increase the surface area and porosity which is important for Li-ion batteries, the starting Si powder was ball-milled and threatened by metal-assisted chemical etching. The mechanochemical treatment resulted in decrease of the particle size from 75 nm to 29 nm, an increase of the BET surface area and average pore size to 16.7 m2/g and 1.26 nm, respectively, and broadening of the X-ray powder diffraction (XRD) lines. The XRD patterns of silver metal-assisted chemical etching (MACE) sample showed strong and narrow diffraction lines typical for powder silicon and low-intensity diffraction lines typical for silver. The metal-assisted chemical etching of starting Si material resulted in a decrease of surface area to 7.3 m2/g and an increase of the average pore size to 3.44 nm. These three materials were used as the anode material in lithium-ion cells, and their electrochemical properties were investigated by cyclic voltammetry and galvanostatic charge-discharge cycles. The enhanced electrochemical performance of the sample prepared by MACE is attributed to increase in pore size, which are large enough for easy lithiation. These are the positive aspects of the application of MACE in the development of an anode material for Li-ion batteries.

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Magnetic polymer gels are a new promising class of nanocomposite gels. In this work, magnetic PEO/iron oxide nanocomposite hydrogels were synthesized using the one-step -irradiation method starting from poly(ethylene oxide) (PEO) and iron(III) precursor alkaline aqueous suspensions followed by simultaneous crosslinking of PEO chains and reduction of Fe(III) precursor. -irradiation dose and concentrations of Fe3+, 2-propanol and PEO in the initial suspensions were varied and optimized. With 2-propanol and at high doses magnetic gels with embedded magnetite nanoparticles were obtained, as confirmed by XRD, SEM and Mössbauer spectrometry. The quantitative determination of -irradiation generated Fe2+ was performed using the 1,10-phenanthroline method. The maximal Fe2+ molar fraction of 0.55 was achieved at 300 kGy, pH = 12 and initial 5% of Fe3+. The DSC and rheological measurements confirmed the formation of a well-structured network. The thermal and rheological properties of gels depended on the dose, PEO concentration and initial Fe3+ content (amount of nanoparticles synthesized inside gels). More amorphous and stronger gels were formed at higher dose and higher nanoparticle content. The properties of synthesized gels were determined by the presence of magnetic iron oxide nanoparticles, which acted as reinforcing agents and additional crosslinkers of PEO chains thus facilitating the one-step gel formation.