CeXO2 (X: Fe, Mn) nanoparticles, synthesized using the coprecipitation route, were investigated for their structural, morphological, magnetic, and electrochemical properties using X-ray diffraction (XRD), field emission transmission electron microscopy (FE-TEM), dc magnetization, and cyclic voltammetry methods. The single-phase formation of CeO2 nanoparticles with FCC fluorite structure was confirmed by the Rietveld refinement, indicating the successful incorporation of Fe and Mn in the CeO2 matrix with the reduced dimensions and band gap values. The Raman analysis supported the lowest band gap of Fe-doped CeO2 on account of oxygen non-stoichiometry. The samples exhibited weak room temperature ferromagnetism, which was found to be enhanced in the Fe doped CeO2 . The NEXAFS analysis supported the results by revealing the oxidation state of Fe to be Fe2+/Fe3+ in Fe-doped CeO2 nanoparticles. Further, the room temperature electrochemical performance of CeXO2 (X: Fe, Mn) nanoparticles was measured with a scan rate of 10 mV s−1 using 1 M KCL electrolyte, which showed that the Ce0.95Fe0.05O2 electrode revealed excellent performance with a specific capacitance of 945 F·g −1 for the application in energy storage devices.

Magnetic nanoparticles of NiFe2O4 were successfully prepared by utilizing the sol–gel techniques. The prepared samples were investigated through various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), dielectric spectroscopy, DC magnetization and electrochemical measurements. XRD data analysed using Rietveld refinement procedure inferred that NiFe2O4 nanoparticles displayed a single-phase nature with face-centred cubic crystallinity with space group Fd-3m. Average crystallite size estimated using the XRD patterns was observed to be ~10 nm. The ring pattern observed in the selected area electron diffraction pattern (SAED) also confirmed the single-phase formation in NiFe2O4 nanoparticles. TEM micrographs confirmed the uniformly distributed nanoparticles with spherical shape and an average particle size of 9.7 nm. Raman spectroscopy showed characteristic bands corresponding to NiFe2O4 with a shift of the A1g mode, which may be due to possible development of oxygen vacancies. Dielectric constant, measured at different temperatures, increased with temperature and decreased with increase in frequency at all temperatures. The Havrilliak–Negami model used to study the dielectric spectroscopy indicated that a NiFe2O4 nanoparticles display non-Debye type relaxation. Jonscher’s power law was utilized for the calculation of the exponent and DC conductivity. The exponent values clearly demonstrated the non-ohmic behaviour of NiFe2O4 nanoparticles. The dielectric constant of the nanoparticles was found to be >300, showing a normal dispersive behaviour. AC conductivity showed an increase with the rise in temperature with the highest value of 3.4 × 10−9 S/cm at 323 K. The M-H curves revealed the ferromagnetic behaviour of a NiFe2O4 nanoparticle. The ZFC and FC studies suggested a blocking temperature of ~64 K. The saturation of magnetization determined using the law of approach to saturation was ~61.4 emu/g at 10 K, corresponding to the magnetic anisotropy ~2.9 × 104 erg/cm3 . Electrochemical studies showed that a specific capacitance of ~600 F g−1 was observed from the cyclic voltammetry and galvanostatic charge–discharge, which suggested its utilization as a potential electrode for supercapacitor applications.

Two-dimensional (2D) nanolayered and nanohybrid structures, which are composed of different species of organic anions and multi-valence inorganic cations, are considered favorable in the field of energy storage for use as supercapacitors. In this study, host–guest interactions were used to build a series of these nanohybrids. The host was the layered double hydroxides of vanadium– cobalt (V/Co) nanolayers with different molar ratios. Cyanate was used as a guest to design a V/Co supercapacitor with a 2D-nanolayered structure. In addition, oxalate was used as a new additive to improve the performance of the V/Co supercapacitor. X-ray diffraction, infrared spectroscopy, thermal analyses, and scanning electron microscopy confirmed the formation of the nanolayered structures of cyanate-V/Co. In the case of the oxalate-V/Co nanostructures, a new phase of cobalt oxalate was produced and combined with the nanolayered structure to build a 3D porous structure. A three-assembly electrode system was used to study the electrochemical supercapacitive behavior of the cyanate-V/Co and oxalate-V/Co nanolayered structures. The results indicated that the OXVC-20 electrode possessed the highest specific capacitance as compared to that of the OXVC-16 and CNOVC electrodes. An excellent stability performance of up to 91% after various charge–discharge cycles was detected for the optimum case. Because of the positive effect of oxalate on the supercapacitance performance of the V/Co supercapacitor, it is suggested as a new track for building active electrodes for high-performance supercapacitor applications.

Herein, we have reported a novel strategy for improving the electrochemical performance of laser-induced graphene (LIG) supercapacitors (SCs). The LIG was prepared using a CO2 laser system. The polyimide polymer was the source material for the fabrication of the LIG. The doping process was performed in situ using the CO2 laser, which works as a rapid thermal treatment to combine graphene and NiO particles. NiO was used to improve the capacitance of graphene by combining an electric double-layer capacitor (EDLC) with the pseudo-capacitance effect. The high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy showed that the structure of the LIG is multilayered and waved. The HRTEM image proves the distribution of NiO fine particles with sizes of 5–10 nm into the graphene layers. The electrochemical performance of the as-prepared LIG was tested. The effect of the combination of the two materials (oxide and carbon) was investigated at different concentrations. The LIG showed a specific capacitance of 69 Fg−1 , which increased up to 174 Fg−1 for the NiO-doped LIG. The stability investigations showed that the electrodes were very stable for more than 1000 cycles. This current study establishes an innovative method to improve the electrochemical properties of LIG.

We present the co-precipitation synthesis of Zn_1-xCd_xWO₄ nanoparticles using only sodium tungstate and cadmium nitrate solutions as precursors, with no complexing agents, templates, or surfactants. Various techniques were used to characterize the synthesized product to determine its crystalline nature and vibrational, optical, and morphological properties. The radiation shielding parameters like mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), ACS, ECS, and Z_eff have been investigated in addition to low half-value layer (HVL) and mean free path (MFP) values, the most critical features of alternative shielding material. The CdWO₄ sample, which had the highest Cd concentration of the samples tested, had the lowest MFP, TVL, and HVL values. Considering these factors, the composite materials were found to have the best shielding characteristics of any of the other samples. The LAC …

In this paper, we have reported a low-concentration active electrolyte of KBrO₃ for the supercapacitor’s application. The electrochemical processes were carried out in two concentrations of KBrO₃ with 0.2 and 0.4 M. Additionally, we have reported a novel strategy for doping graphene during its fabrication process with a potassium bromide (KBr) solution. The chemical doping of graphene with KBr improved the electrochemical properties of graphene used as supercapacitors. HRTEM images confirmed the multi-layer graphene obtained by CO₂ laser based on polyimide. The effect of KBr on the graphene lattice has been studied using Raman spectroscopy. The two electrodes of graphene and KBr-doped graphene were subjected to the electrochemical properties study as a supercapacitor by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge techniques. The results exhibited the successful method of graphene doping and the stability of using KBrO₃ as a suitable electrolyte for electrochemical processes with this lower molarity. The specific capacitance of the pristine graphene capacitor in 0.2 M of KBrO₃ was 33 Fg⁻¹, while this value increased up to 70 Fg⁻¹ for KBr-doped graphene in 0.4 M of KBrO₃. The specific capacity in mAhg⁻¹ has also increased twofold. The results exhibited the possibility of using KBrO₃ as an electrolyte. The supercapacitor performance almost showed good stability in the life cycle.

Results of crystallization kinetics for Se₈₈Te₁₀Ag₂ glass using differential scanning calorimetry under non-isothermal condition are described and discussed. The glass has a single glass transition and two crystalline phases that overlap. The Gaussian fit model was used to separate the overlapping crystalline phases. By applying the Matusita et al. approach to analyses the data, it was possible to determine the activation energy (E_c) and Avrami exponent (n) for the two phases. The average E_c values for the first and the second phases are 126.16 and 113.99 kJ mol⁻¹, respectively. It was shown that the activation energy strongly depended on the heating rate. Using the Kissinger–Akahira–Sunose method, the variable activation energies with crystalline fraction are calculated. This variation demonstrates how the transition from the amorphous to the crystalline phase is a complicated process requiring several nucleation and growth mechanisms. It was discussed if the Johnson–Mehl–Avrami model to describe the crystallization for the composition under investigation. The results show SB(M, N) that model is more appropriate to represent the crystallization process for the examined composition. While the results agree with JMA models at low heating rates. Through the use of scanning electron microscopy and X-ray diffraction, the crystalline phases for the two stages were identified.