Search Results (30)

This study employed a simple and cost-effective method for developing NiO with reduced optical band gaps that can be combined with nanostructured polyaniline (PANI). The composite systems were used as electrocatalytic and electrode materials in oxygen evolution reactions (OER) and in supercapacitor applications. We prepared the composite material in two stages: NiO was prepared with a reduced optical band gap by combining it with wheat peel extract. This was followed by the incorporation of PANI nanoparticles during the chemical oxidation polymerization process. A variety of structural characterization techniques were employed, including scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). A surface-modified NiO/PANI composite with enhanced surface area, fast charge transfer rate, and redox properties was produced. When NiO/PANI composites were tested in KOH electrolytic solution, 0.5 mL of wheat peel extract-mediated NiO/PANI demonstrated excellent electrochemical performance. It was found that the asymmetric supercapacitor (ASC) device had the highest specific capacitance of 404 Fg⁻¹ at a current density of 4 Ag⁻¹. In terms of energy density and power density, the ASC device was found to have 140 Whkg⁻¹ and 3160 Wkg⁻¹, respectively. The ASC device demonstrated excellent cycling stability and charge storage rates, with 97.9% capacitance retention and 86.9% columbic efficiency. For the OER process, an overpotential of 320 mV was observed at a current density of 10 mA/cm². It was found that the NiO/PANI composite was highly durable for a period of 30 h. A proposed hypothesis suggested that reducing the optical band gap of NiO and making its composites with PANI could be an appealing approach to developing next-generation electrode materials for supercapacitors, batteries, and fuel cells. Full article

Energy and environmental challenges are driving researchers to explore cost-effective and eco-friendly nanomaterial fabrication methods. In this study, Atmospheric Pressure Microplasma (AMP) was used to synthesize iron oxide nanoparticles at varying molar concentrations of ferrous sulfate (0.5 M, 1 M, and 1.5 M) under a 15 kV discharge voltage for 90 min. The X-ray diffraction (XRD) results confirmed the formation of mixed cubic and hexagonal phases of magnetite and hematite nanoparticles. The particle size, calculated using the Debye–Scherrer formula, ranged from 9 to 11 nm, depending on the precursor concentration. Scanning electron microscopy (SEM) images revealed spherical nanoparticles at 0.5 M, while agglomeration occurred at 1.5 M. The energy-dispersive X-ray spectroscopy (EDS) analysis confirmed the presence of iron and oxygen in the synthesized nanoparticles. Fourier-transform infrared (FTIR) and UV spectroscopy showed characteristic absorption bands of iron oxide. The impact of the particle size and lattice strain on the optical properties of the nanoparticles was also studied. Smaller nanoparticles exhibited an excellent specific capacitance (627) and a strong charge–discharge performance in a 3 M KOH solution, with a high energy density (67.72) and power density (2227). As photocatalysts, the nanoparticles demonstrated a 97.5% and 96.8% degradation efficiency against methylene blue (MB) and methyl orange (MO), respectively, with high rate constants. These results surpass previous reports. The enhanced electrochemical performance and photocatalytic activity are attributed to the high-quality iron oxide nanoparticles, showing an excellent cyclic stability, making them promising for supercapacitors and environmental remediation. Full article

Nitrogen-doped graphene quantum dots (N-GQDs) are widely used in biosensing, catalysis, and energy storage due to their excellent conductivity, high specific surface area, unique quantum size effects, and optical properties. In this paper, we successfully synthesized N-GQDs using a facile hydrothermal approach and investigated the effects of different hydrothermal temperatures and times on the morphology and structure of N-GQDs. The results indicated that the size of N-GQDs gradually increased and they eventually aggregated into graphene fragments with increasing temperature or reaction time. Notably, N-GQDs synthesized at 180 °C for 6 h exhibited the most uniform size, with an average diameter of approximately 3.48 nm, a height of 5–6 graphene layers, as well as favorable fluorescence properties. Moreover, the surface of N-GQDs contained abundant oxygen- and nitrogen-containing functional groups, which could provide numerous active sites for electrode reactions. The assembled electrode exhibited typical pseudocapacitive behavior with exceptional electrochemical performance, achieving a specific capacitance of 102 F g⁻¹ at a current density of 1 A g⁻¹. In a 10,000-cycle test, the electrode demonstrated excellent cycling stability with a capacitance retention rate of 78.5%, which laid the foundation for practical application of the electrode. This work successfully applied N-GQDs in supercapacitors, offering new insights into their development for the energy storage field. Full article

Due to photovoltaic (PV) power generation depending on the environment, its output power is volatile, and effectively dealing with its power fluctuation has become a key concern. Aiming at this problem, this article presents an optical storage cooperative control technology based on an Alternating Sequence Filter (ASF), which controls the power management of the Energy Storage System (ESS) consisting of a vanadium redox battery, battery, and supercapacitor. Firstly, an ASF is designed to stabilize the PV power generation by alternating sequence and improve system response speed. Secondly, according to the output signal of the filter, the charge and discharge of the three energy storage units are dynamically adjusted, and the power fluctuation is compensated in real-time to improve the system stability and conversion efficiency. Finally, the simulation results of actual illumination show that the control strategy calls the ESS to stabilize the power fluctuation, so that the power of the direct current bus is stabilized at about 15 kw, and the fluctuation is maintained between −4.48% and 4.05%. The strategy significantly reduces power fluctuation and improves the dynamic response ability and energy storage utilization of the system. Full article

The development of eco-friendly, cost-effective, and naturally abundant electrode materials for supercapacitors is gaining critical importance in current energy storage research. This study focuses on the synthesis of tin sulfide (SnSx) films via the eco-friendly successive ionic layer adsorption and reaction (SILAR) method, employing varying quantities of L-ascorbic acid (0.8 and 1.0 g) as a reducing agent. Tin sulfide films were deposited on fluorine-doped tin oxide (FTO) glass substrates and subsequently annealed in an inert atmosphere at temperatures ranging from 200 to 400 °C, resulting in thin films of varying thicknesses (100–420 nm). The structural and compositional characteristics of the films were thoroughly analyzed using Raman spectroscopy to confirm the purity and spectroscopic signatures of the sulfides. Further characterization was performed to assess the films’ morphology (scanning electron microscopy, SEM), phase composition (X-ray diffraction, XRD), surface chemical states (X-ray photoelectron spectroscopy, XPS), optical properties (UV–Vis spectroscopy), and electrical properties (Hall measurements). The gathered data were then used to evaluate the potential of tin sulfide films as electrode materials in supercapacitors, highlighting their suitability for sustainable energy storage applications. Full article

This study explores the influence of solution concentration, specifically that of water and ethylene glycol mixtures, on the optical and supercapacitive properties of cobalt tungstate (CoWO₄) nanoparticles. CoWO₄ nanoparticles were synthesized using varying ratios of water to ethylene glycol to ascertain the optimal conditions for enhanced performance. Detailed characterization was conducted using UV–Vis spectroscopy, photoluminescence (PL) spectroscopy, cyclic voltammetry (CV), and galvanostatic charge–discharge (GCD) to evaluate the optical properties and electrochemical behavior, respectively. The results revealed that the solution concentration significantly impacted the bandgap, absorbance, and emission properties of the CoWO₄ nanoparticles. Effective bandgap tuning was achieved by altering the solution concentration. When using only water, the nanoparticles displayed the lowest bandgap of 2.57 eV. In contrast, a solution with equal water and ethylene glycol concentrations resulted in the highest bandgap of 2.65 eV. Additionally, the electrochemical studies demonstrated that the water/ethylene glycol ratio markedly influenced the charge storage capacity and cyclic stability of the nanoparticles. The results indicated that the solvent concentration significantly influenced the crystallinity, particle size, and surface morphology of the CoWO₄ nanoparticle nanoparticles, which affected their optical properties and electrochemical performance. Notably, nanoparticles synthesized with a 1.25:0.75 proportion of water to ethylene glycol exhibited superior supercapacitive performance, with a specific capacitance of 661.82 F g⁻¹ at a current density of 7 mA cm⁻² and 106% capacitance retention after 8000 charge–discharge cycles. These findings underscore the critical role of solvent composition in tailoring the functional properties of CoWO₄ nanoparticles, providing insights for their application in optoelectronic devices and energy storage systems. Full article

In the evolving landscape of portable electronics, there is a critical demand for components that meld stretchability with optical transparency, especially in supercapacitors. Traditional materials fall short in harmonizing conductivity, stretchability, transparency, and capacity. Although poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) stands out as an exemplary candidate, further performance enhancements are necessary to meet the demands of practical applications. This study presents an innovative and effective method for enhancing electrochemical properties by homogeneously incorporating Ru(III) into PEDOT:PSS. These Ru(III) PEDOT:PSS complexes are readily synthesized by dipping PEDOT:PSS films in RuCl₃ solution for no longer than one minute, leveraging the high specific capacitance of Ru(III) while minimizing interference with transmittance. The supercapacitor made with this Ru(III) PEDOT:PSS complex demonstrated an areal capacitance of 1.62 mF cm⁻² at a transmittance of 73.5%, which was 155% higher than that of the supercapacitor made with PEDOT:PSS under comparable transparency. Notably, the supercapacitor retained 87.8% of its initial capacitance even under 20% tensile strain across 20,000 cycles. This work presents a blueprint for developing stretchable and transparent supercapacitors, marking a significant stride toward next-generation wearable electronics. Full article

An ultrasound-assisted probe sonication route effectively prepared pure CuO and two-dimensional CuO-ZnO nanocomposites (NCs) for different ratios of CuO and ZnO, and the experimental and theoretical methods investigated the structural, photocatalytic, and electrochemical properties. The XRD (X-ray diffraction) patterns revealed a crystallite size (D) range of 25 to 31 nm for pure CuO and CuO-ZnO NCs. According to calculations, the sample’s optical energy bandgap value (Eg) for the NCs is between 1.72 and 2.15 eV. Under UV light irradiation, the photocatalytic discoloration of pure CuO and CuO-ZnO NCs on fast blue (FB) dye was assessed. Under the influence of UV light, the CuO with 10% ZnO composite degrades 83.4% of the dye, which is greater than pure CuO and other NCs. The electrochemical properties of the prepared NCs materials have been studied using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The specific capacitance values were found to be 248 Fg⁻¹, 301 Fg⁻¹, 352 Fg⁻¹, and 277 Fg⁻¹ for CuO, CuO + 5% ZnO, CuO + 10% ZnO, and CuO + 15% ZnO, respectively, at 1 A/g current density. Galvanostatic charge–discharge tests for these designed NCs show excellent capacitance performance in supercapacitors applications. These innovative results could be considered for expanding novel resources to scale for dual applications in photocatalysis and supercapacitors. Full article

The molecular engineering of conjugated systems has proven to be an effective method for understanding structure–property relationships toward the advancement of optoelectronic properties and biosensing characteristics. Herein, a series of three thieno[3,4-c]pyrrole-4,6-dione (TPD)-based conjugated monomers, modified with electron-rich selenophene, 3,4-ethylenedioxythiophene (EDOT), or both building blocks (Se-TPD, EDOT-TPD, and EDOT-Se-TPD), were synthesized using Stille cross-coupling and electrochemically polymerized, and their electrochromic properties and applications in a glucose biosensing platform were explored. The influence of structural modification on electrochemical, electronic, optical, and biosensing properties was systematically investigated. The results showed that the cyclic voltammograms of EDOT-containing materials displayed a high charge capacity over a wide range of scan rates representing a quick charge propagation, making them appropriate materials for high-performance supercapacitor devices. UV-Vis studies revealed that EDOT-based materials presented wide-range absorptions, and thus low optical band gaps. These two EDOT-modified materials also exhibited superior optical contrasts and fast switching times, and further displayed multi-color properties in their neutral and fully oxidized states, enabling them to be promising materials for constructing advanced electrochromic devices. In the context of biosensing applications, a selenophene-containing polymer showed markedly lower performance, specifically in signal intensity and stability, which was attributed to the improper localization of biomolecules on the polymer surface. Overall, we demonstrated that relatively small changes in the structure had a significant impact on both optoelectronic and biosensing properties for TPD-based donor–acceptor polymers. Full article

Batteries and supercapacitors are the next-generation alternative energy resources that can fulfil the requirement of energy demand worldwide. In regard to the development of efficient energy storage devices, various materials have been tested as electrode materials. Graphene quantum dots (GQDs), a new class of carbon-based nanomaterial, have driven a great research interest due to their unique fundamental properties. High conductivity, abundant specific surface area, and sufficient solubility, in combination with quantum confinement and edge effect, have made them appropriate for a broad range of applications such as optical, catalysis, energy storage and conversion. This review article will present the latest research on the utilization of GQDs and their composites to modify the electrodes used in energy storage devices. Several major challenges have been discussed and, finally, future perspectives have been provided for the better implementation of GQDs in the energy storage research. Full article

Herein, we explore the supercapacitor and photocatalytic applications of poly(1-naphthylamine) (PNA) nanoparticles. The PNA nanoparticles were synthesized by using polymerization of 1-naphthylamine and characterized with several techniques in order to understand the morphological, structural, optical and compositional properties. The structural and morphological properties confirmed the formation of crystalline nanoparticles of PNA. The Fourier-transform infrared (FTIR) spectrum revealed the successful polymerization of 1-naphthylamine monomer to PNA. The absorption peaks that appeared at 236 and 309 nm in the UV–Vis spectrum for PNA nanoparticles represented the π–π^* transition. The supercapacitor properties of the prepared PNA nanoparticles were evaluated with cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) methods at different scan rates and current densities, respectively. The effective series resistance was calculated using electrochemical impedance spectroscopy (EIS), resulting in a minimum resistance value of 1.5 Ω. The highest specific capacitance value of PNA was found to be 255 Fg⁻¹. This electrode also exhibited excellent stability with >93% capacitance retention for 1000 cycles, as measured at 1A g⁻¹. Further, the prepared PNA nanoparticles were used as an effective photocatalyst for the photocatalytic degradation of methylene blue (MB) dye, which exhibited ~61% degradation under UV light irradiation. The observed results revealed that PNA nanoparticles are not only a potential electrode material for supercapacitor applications but also an efficient photocatalyst for the photocatalytic degradation of hazardous and toxic organic dyes. Full article

BiFe_1−xCr_xO_3, (0 ≤ x ≤ 10) nanoparticles were prepared through the sol–gel technique. The synthesized nanoparticles were characterized using various techniques, viz., X-ray diffraction, high-resolution field emission scanning electron microscopy (HRFESEM), energy dispersive spectroscopy (EDS), UV–Vis absorption spectroscopy, photoluminescence (PL), dc magnetization, near-edge X-ray absorption spectroscopy (NEXAFS) and cyclic voltammetry (CV) measurements, to investigate the structural, morphological, optical, magnetic and electrochemical properties. The structural analysis showed the formation of BiFeO₃ with rhombohedral (R3c) as the primary phase and Bi₂₅FeO₃₉ as the secondary phase. The secondary phase percentage was found to reduce with increasing Cr content, along with reductions in crystallite sizes, lattice parameters and enhancement in strain. Nearly spherical shape morphology was observed via HRFESEM with Bi, Fe, Cr and O as the major contributing elements. The bandgap reduced from 1.91 to 1.74 eV with the increase in Cr concentration, and PL spectra revealed emissions in violet, blue and green regions. The investigation of magnetic field (H)-dependent magnetization (M) indicated a significant effect of Cr substitution on the magnetic properties of the nanoparticles. The ferromagnetic character of the samples was found to increase with the increase in the Cr concentration and the increase in the saturation magnetization. The Fe (+3/+4) was dissolved in mixed-valence states, as found through NEXAFS analysis. Electrochemical studies showed that 5%-Cr-doped BFO electrode demonstrated outstanding performance for supercapacitors through a specific capacitance of 421 F g⁻¹ measured with a scan rate of 10 mV s⁻¹. It also demonstrated remarkable cyclic stability through capacitance retention of >78% for 2000 cycles. Full article

Optically controlled supercapacitors (S-C) could be of interest to the sensor community, as well as set the stage for novel optoelectronic charging devices. Here, structures constructed of two parallel transparent current collectors (indium-tin-oxide, ITO films on glass substrates) were considered. Active-carbon (A-C) films were used as electrodes. Two sets of electrodes were used: as-is electrodes that were used as the reference and electrodes that were embedded with submicron- or micron-sized titanium oxide (TiO₂) colloids. While immersed in a 1 M Na₂SO₄, the electrodes exhibited minimal thermal effects (<3 °C) throughout the course of experiments). The optically induced capacitance increase for TiO₂-embedded S-C was large of the order of 30%, whereas S-C without the TiO₂ colloids exhibited minimal optically related effects (<3%). Spectrally, the blue spectral band had a relatively larger impact on the light-induced effects. A lingering polarization effect that increased the cell capacitance in the dark after prolonged light exposure is noted; that effect occurred without an indication of a chemical reaction. Full article

We report on the synthesis of titanium dioxide by titanium carbide for the preparation of hybrid material reinforced with polyaniline (PANI@TiO₂–TiC) using the in situ polymerization technique. The effectiveness of the samples on the thermal, optical and electrochemical properties was investigated. The XRD, XPS, FTIR, SEM and TEM results confirm the successful synthesis of the PANI, PANI@TiC and PANI@TiO₂–TiC samples. Through this, a good connection, an excellent relationship between the structures and the properties of the synthesized hybrid materials were obtained. Moreover, the electrical conductivity and optical bandgap were also tested. Remarkably good electrochemical characteristics were identified by cyclic voltammetry. Moreover, the galvanostatic charge–discharge (GCD) of the supercapacitor was remarkably high. Cyclic stability showed good retention after 1500 cycles at 1.5 A·g⁻¹. Full article

g-C₃N₄ has drawn lots of attention due to its photocatalytic activity, low-cost and facile synthesis, and interesting layered structure. However, to improve some of the properties of g-C₃N₄, such as photochemical stability, electrical band structure, and to decrease charge recombination rate, and towards effective light-harvesting, g-C₃N₄–metal oxide-based heterojunctions have been introduced. In this review, we initially discussed the preparation, modification, and physical properties of the g-C₃N₄ and then, we discussed the combination of g-C₃N₄ with various metal oxides such as TiO₂, ZnO, FeO, Fe₂O₃, Fe₃O₄, WO₃, SnO, SnO₂, etc. We summarized some of their characteristic properties of these heterojunctions, their optical features, photocatalytic performance, and electrical band edge positions. This review covers recent advances, including applications in water splitting, CO₂ reduction, and photodegradation of organic pollutants, sensors, bacterial disinfection, and supercapacitors. We show that metal oxides can improve the efficiency of the bare g-C₃N₄ to make the composites suitable for a wide range of applications. Finally, this review provides some perspectives, limitations, and challenges in investigation of g-C₃N₄–metal-oxide-based heterojunctions. Full article