Browsing by Subject "Supercapacitors"

Now showing 1 - 6 of 6

Open Access
Electrochemical synthesis of mesoporous architectured Ru films using supramolecular templates
(Wiley-VCH Verlag, 2020) Kani, K.; Henzie, J.; Dağ, Ömer; Wood, K.; Iqbal, M.; Lim, H.; Jiang, B.; Salomon, C.; Rowan, A. E.; Hossain, M. S. A.; Na, J.; Yamauchi, Y.
The electrochemical synthesis of mesoporous ruthenium (Ru) films using sacrificial self‐assembled block polymer micelles templates, and its electrochemical surface oxidation to RuOx is described. Unlike standard methods such as thermal oxidation, the electrochemical oxidation method described here retains the mesoporous structure. Ru oxide materials serve as high‐performance supercapacitor electrodes due to their excellent pseudocapacitive behavior. The mesoporous architectured film shows superior specific capacitance (467 F g−1 Ru) versus a nonporous Ru/RuOx electrode (28 F g−1 Ru) that is prepared via the same method but omitting the pore‐directing polymer. Ultrahigh surface area materials will play an essential role in increasing the capacitance of this class of energy storage devices because the pseudocapacitive redox reaction occurs on the surface of electrodes.
Open Access
Overcoming instability challenges of binder-free, self-standing 1T-TiS2 electrodes in aqueous symmetric supercapacitors through dopamine functionalization
(ELSEVIER, 2025-03) Uçar, Ali Deniz; Bağlıcakoğlu, Sümeyye Kandur; Durukan, Mete Batuhan; Cugunlar, Murathan; Öz, Sena; Koçak, Yusuf; Ülgüt, Burak; Özensoy, Emrah; Ünalan, Hüsnü Emrah
Two-dimensional materials draw considerable interest for energy storage. Semimetallic phases of transition metal dichalcogenides (TMDs), notably titanium disulfide (TiS2), are extensively studied for their distinctive electronic, chemical, and optical traits. TiS2, initially proposed for Li-ion batteries, holds promise for supercapacitors, although its utilization faces stability challenges in aqueous environments. Herein, electrically conducting and surface-passivated 2D 1T-TiS2 flakes were fabricated and tailored for application as electrodes in supercapacitors with enhanced durability. For this purpose, self-standing and flexible 1T-TiS2 films were fabricated using vacuum filtration and treated with dopamine (DA) to obtain electrochemically stable supercapacitor electrodes in aqueous environments. During DA treatment, in-situ generation of hydrogen peroxide (H2O2) leads to the formation of a thin titanium dioxide (TiO2) overlayer on TiS2, enhancing oxidation stability. At a scan rate of 10 mV s−1, a single electrode demonstrated a gravimetric specific capacitance of 128 F g−1, a volumetric specific capacitance of 122 F cm−3, and an areal specific capacitance of 244 mF cm−2. The symmetric supercapacitor device demonstrated an impressive capacity retention of 96.1 % after 10000 cycles and 85.5 % after 18000 cycles. These results pave the way for utilizing 2D 1T-TiS2 in aqueous environments, expanding its possible applications and holding promise for significant advancements in the field.
Open Access
Preparation and capacitance properties of graphene quantum Dot/NiFe−layered double‐hydroxide nanocomposite
(Wiley-VCH Verlag, 2021-01) Samuei, S.; Rezvani, Z.; Shomali, A.; Ülker, E.; Karadaş, Ferdi
A new composite from graphene quantum dots (GQDs) and NiFe layered double hydroxide was successfully prepared by the coprecipitation method under optimal conditions. The nanoparticles of the composite were analyzed by X‐ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA) to obtain the structure, composition and morphology information. Also, the electrochemical properties were investigated by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The nanocomposite displays a specific capacitance of 712.7 F g−1 and excellent cycle life after 2500 cycles by applying 10 A g−1 of the current density in 1 M KOH electrolyte, which confirms that the nanocomposite has superb capacitance retention (∼94.8 %) and can be used as a capable supercapacitor. Furthermore, this study provides a desirable procedure for the preparation of novel nanocomposites based on graphene quantum dots, which can be used in energy storage/conversion devices.
Open Access
Recent advancements in the synthetic mechanism and surface engineering of transition metal selenides for energy storage and conversion applications
(John Wiley and Sons Inc., 2023-04) Khan, S.; Ullah, N.; Mahmood, A.; Saad, M.; Ullah, Z.; Ahmad, Waqar; Ullah, S.
Novel catalytic materials are under investigation to find convincing energy alternatives. In this context, transition metal selenides (TMSes) are found to be feasible, ecofriendly, and effective electrocatalysts with futuristic characteristics. A deep and comprehensive investigation on metal selenides for energy conversion and storage application is summarized in this review article. Different methods such as hydrothermal, solvothermal, coprecipitation, hot injection, successive ionic layer adsorption reaction, polyol, and others can be used for the synthesis of metal selenides based electrocatalysts, with different morphologies and compositions. The morphology of metal selenides is strongly controlled by factors such as reaction time, temperature, pH of the reaction medium, and surfactant. The electrochemical applications of metal selenides are governed by morphology, active spots for reaction, surface engineering, and confinement. It is concluded that TMSes deliver high performance with large surface area, which is possible due to their porous or 3D morphology. The TMSes with multimetal or with doping metal/nonmetals perform better compared to single atoms. It is concluded that the reaction mechanism of hydrogen evolution reaction and oxygen evolution reaction is a primary tool to better understand the system to develop more efficient catalysts for practical application.
Open Access
RuO2 supercapacitor enables flexible, safe, and efficient optoelectronic neural interface
(Wiley-VCH Verlag GmbH & Co. KGaA, 2022-08-01) Karatum, O.; Yildiz, E.; Kaleli, H. N.; Sahin, A.; Ulgut, Burak; Nizamoglu, S.
Optoelectronic biointerfaces offer a wireless and nongenetic neurostimulation pathway with high spatiotemporal resolution. Fabrication of low-cost and flexible optoelectronic biointerfaces that have high photogenerated charge injection densities and clinically usable cell stimulation mechanism is critical for rendering this technology useful for ubiquitous biomedical applications. Here, supercapacitor technology is combined with flexible organic optoelectronics by integrating RuO2 into a donor–acceptor photovoltaic device architecture that facilitates efficient and safe photostimulation of neurons. Remarkably, high interfacial capacitance of RuO2 resulting from reversible redox reactions leads to more than an order-of-magnitude increase in the safe stimulation mechanism of capacitive charge transfer. The RuO2-enhanced photoelectrical response activates voltage-gated sodium channels of hippocampal neurons and elicits repetitive, low-light intensity, and high-success rate firing of action potentials. Double-layer capacitance together with RuO2-induced reversible faradaic reactions provide a safe stimulation pathway, which is verified via intracellular oxidative stress measurements. All-solution-processed RuO2-based biointerfaces are flexible, biocompatible, and robust under harsh aging conditions, showing great promise for building safe and highly light-sensitive next-generation neural interfaces.
Open Access
Two-dimensional mesoporous vanadium phosphate nanosheets through liquid crystal templating method toward supercapacitor application
(Elsevier, 2018) Mei, P.; Kaneti, Y. V.; Pramanik, M.; Takei, T.; Dağ, Ömer; Sugahara, Y.; Yamauchi, Y.
Mesoporous vanadium phosphate (VOPO4) nanosheets have been successfully synthesized through an easy and reproducible lyotropic liquid crystals (LLC) templating approach for the first time. Using the triblock copolymer (P123) as a surfactant, VOPO4 precursor with a well-developed 2D hexagonal mesostructure can be obtained. Following complete removal of the template by calcination, crystallized VOPO4 frameworks with less-ordered mesostructure are achieved. The as-prepared mesoporous VOPO4 nanosheets exhibit superior pseudocapacitive performance (767 F g‒1 at 0.5A g‒1) by virtue of the favorable mesostructure that gives rise to abundant easily accessible redox active sites as well as reinforced charge transfer and ion diffusion properties. The charge storage mechanism of the mesoporous VOPO4 nanosheets has been experimentally demonstrated to be based on the reversible two-step redox reactions between V(V) and V(III) in acidic medium. This advantageous LLC templating strategy is expected to open up a new route for designing various mesoporous metal phosphates with superior electrochemical performance for utilization in energy storage devices.