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It is imperative to develop high-efficiency polymer electrolytes to advance energy storage technologies. The goal of this research is to use the exceptional properties of ionic liquids such as their superior ionic conductivity, thermal stability, and adjustable physical and chemical characteristics to improve polymer electrolytes through doping. This study explores the incorporation of ionic liquids into polymer matrices to create novel ionic-liquid-doped polymer electrolytes (ILDPEs). We synthesized a ILDPEs using Poly(ethyl methacrylate) (PEMA) as the host polymer with salt sodium iodide (NaI) doped with a new ionic liquid (1-hexyl-3-methylimidazolium iodide) synthesized using solution cast technique. Impedance spectroscopy revealed that doping ionic liquid enhances the ionic conductivity of the PEMA + NaI complex. Ionic conductivity significantly increased upon the addition of the ionic liquid (IL), reaching a maximum value of 7.7 × 10–4 S/cm at room temperature. The ionic transference number (tion) for the polymer electrolyte with the highest ionic conductivity was calculated using Wagner polarization method while electrochemical stability window was calculated by linear Sweep Voltammetry. The crystalline nature of the ILDPEs films was studied using Polarizing Optical Microscopy (POM). To confirm the complex formation and bonding structure, Fourier-transform infrared spectroscopy (FTIR) and X-Ray Diffraction (XRD) were also employed. Finally, dye-synthesized solar cell (DSSC) and electric double-layer capacitor (EDLC) were fabricated using the highest ionic conducting polymer electrolytes. [ABSTRACT FROM AUTHOR]

Herein, we report a facile surfactant-assisted hydrothermal synthesis of layered MnO2 for supercapacitor applications. The effect of surfactants (sodium dodecylsulfonate, hexadecyltrimethylammonium bromide, and t-octylphenoxypolyethoxyethanol) on the morphology, porosity, and electrochemical performance of MnO2 has been established. Compared to anionic and cationic surfactants, the non-ionic surfactant prevented agglomeration of nanoparticles during synthesis because of the steric hindrance, which produced a more developed surface of MnO2 particles that facilitated ion transport. Moreover, combining the porous structure of the MnO2 electrode with the redox-active K3Fe(CN)6–Na2SO4 electrolyte significantly improved the specific capacitance up to 470 F·g−1 at 0.5 A·g−1. The Coulombic efficiency of 99.9% after 5000 charge/discharge cycles and high electrochemical performance make layered MnO2 a promising electrode material for energy storage devices. [ABSTRACT FROM AUTHOR]

The functionalization of copolyfluorenes containing dicyanophenanthrene units by closo-decaborate anion is described. Target copolyfluorenes were analyzed using SEM, UV-vis, luminescence, NMR, and Fourier-transform infrared (FTIR) spectroscopy. The effect of complexation with the closo-decaborate anion on the photophysical properties was studied both experimentally and theoretically. The PL data indicate an efficient charge transfer from fluorene to the dicyanophenanthrene units coordinated to the closo-decaborate. The coordination of closo-decaborate clusters to the nitrile groups of copolyfluorenes provides an important route to new materials for sensors and light-emitting devices while, at the same time, serving as a platform for further study of the nature of boron clusters. [ABSTRACT FROM AUTHOR]

La2O3 nanoparticles stabilized on carbon nanoflake (CNF) matrix were synthesized and graphitized to produce core-shell structures La2O3/CNFs@C. Further oxidation of these structures by nitric acid vapors for 1, 3 or 6 h was performed, and surface-oxidized particles La2O3/CNFs@C_x (x = 1, 3, 6) were produced. Bulk and surface compositions of La2O3/CNFs@C and La2O3/CNFs@C_x were investigated by thermogravimetric analysis and X-ray photoelectron spectroscopy. With increasing the duration of oxidation, the oxygen and La2O3 content in the La2O3/CNFs@C_x samples increased. The electronic structures of samples were assessed by electron paramagnetic resonance. Two paramagnetic centers were associated with unpaired localized and mobile electrons and were registered in all samples. The correlation between bulk and surface compositions of the samples and their electronic structures was investigated for the first time. The impact of the ratio between sp2- and sp3-hybridized C atoms, the number and nature of oxygen-containing groups on the surface and the presence and proportion of coordinated La atoms on the EPR spectra was demonstrated. [ABSTRACT FROM AUTHOR]

The thermoelectric properties of a new type of Pr2-xSrxFeCrO6 double perovskite were investigated at higher temperature after its sol-gel synthesis. The XRD results validate the single-phase orthorhombic structure, and the crystallite sizes meet the morphological measurements. XPS examination, which formed the defect sites in these oxides, confirmed the varied oxidation states of constituents. The temperature-dependent electrical conductivity (σ) was poor in the original Pr2FeCrO6 composition, but after substituting Sr on the Pr-site, a significant rise in σ with two semiconductors and one metal transition was observed. A positive Seebeck coefficient confirmed the presence of a p-type charge carrier in the entire composition, and the charge transport mechanism was driven by the SPH model. Thermal conductivity increases in all doped samples, while it decreases in pristine compounds over the broad analyzed temperature range. Thermal expansion coefficient increased after doping in oxygen-deficient compound. The PrSrFeCrO6 compound had the maximum ZT (0.105), which was 3.9 times higher than that of the pristine compound. [ABSTRACT FROM AUTHOR]

X-ray photoelectron emission spectra of thermally reduced graphene oxide samples and carbon nanotubes (CNTs) with various oxidation degrees are presented in this paper. A method for the reconstruction of differential electron inelastic scattering cross sections from the energy loss spectra of photoelectrons is described and discussed. The analysis of the part of the characteristic photoelectron energy loss spectrum adjacent to the C1 peak indicated a considerable influence of the thermal reduction of graphene oxide on the electron properties of the samples obtained. On the contrary, the oxidation of CNTs by refluxing in a concentrated HNO3 solution does not change the free electron excitation spectrum. [ABSTRACT FROM AUTHOR]

We report the comparison of the electrochemical performances of α-MnO2 and δ-MnO2 produced by hydrothermal treatment. The structure and morphology of these materials were analyzed by SEM, HRTEM, XRD, and XPS, while their electrochemical properties were tested in the 1 M Na2SO4 aqueous electrolyte by cyclic voltammetry, galvanostatic charge–discharge measurements, and electrochemical impedance spectroscopy. The specific capacitance of δ-MnO2 at 1 mV·s−1 was 4.8 times higher than that of α-MnO2 (211 vs. 44 F·g−1) because of the layered structure of δ-MnO2 that provided better availability of the electrode surface for electrolyte ions during charge–discharge cycles and pseudocapacitance behavior attributed to faradaic redox reactions. Moreover, δ-MnO2 revealed high electrochemical stability (more than 98% of the initial capacitance after 5000 charge/discharge cycles) confirming its good performance as an electrode material for pseudocapacitors. The contributions of surface and diffusion capacitances were analyzed by the differentiation method. [ABSTRACT FROM AUTHOR]