An efficient electrode material for high performance solid-state hybrid supercapacitors based on a Cu/CuO/porous carbon nanofiber/TiO2 hybrid composite

Boosting Supercapacitor Efficiency with Amorphous Biomass-Derived C@TiO2 Composites

Carbon materials are readily available and are essential in energy storage. One of the routes used to enhance their surface area and activity is the decoration of carbons with semiconductors, such as amorphous TiO2, for application in energy storage devices.

Electrospun network based on polyacrylonitrile-polyphenyl/titanium oxide nanofibers for high-performance supercapacitor device

Nanofibers and mat-like polyacrylonitrile-polyphenyl/titanium oxide (PAN-Pph./TiO2) with proper electrochemical properties were fabricated via a single-step electrospinning technique for supercapacitor application. Scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), thermogravimetry (TGA), fourier transform infrared (FTIR), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) were conducted to characterize the morphological and chemical composition of all fabricated nanofibers. Furthermore, the electrochemical activity of the fabricated nanofibers for energy storage applications (supercapacitor) was probed by cyclic voltammetry (CV), charge-discharge (CD), and electrochemical impedance spectroscopy (EIS). The PAN-PPh./TiO2 nanofiber electrode revealed a proper specific capacitance of 484 F g-1 at a current density of 11.0 A g-1 compared with PAN (198 F g-1), and PAN-PPh. (352 F g-1) nanofibers using the charge-discharge technique. Furthermore, the PAN-PPh./TiO2 nanofiber electrode displayed a proper energy density of 16.8 Wh kg-1 at a power density (P) of 2749.1 Wkg-1. Moreover, the PAN-PPh./TiO2 nanofiber electrode has a low electrical resistance of 23.72 Ω, and outstanding cycling stability of 79.38% capacitance retention after 3000 cycles.

Selective Oxidation of Glycerol to Lactic Acid Catalyzed by CuO/Activated Carbon and Reaction Kinetics

Activated carbon-supported CuO catalysts were prepared by an ammonia evaporation method and applied to catalyze the selective oxidation of glycerol to lactic acid. The effects of CuO loadings on the structure and catalytic performance of the catalyst were investigated. Results showed that CuO could be dispersed uniformly on the surface of activated carbon, promoting the increase of the reaction rate and accelerating the glycerol conversion significantly. As CuO loadings increased, the rate of glycerol consumption and yield to lactic acid was increased. However, too high CuO loadings would destroy the original pore structure of activated carbon and aggravate the agglomeration of CuO, resulting in a decrease in the catalytic performance of the catalyst. The best catalytic performance was obtained over 10% CuO/AC when the reaction temperature was 190 °C and the reaction time was 5 h. At this point, the selectivity to lactic acid reached 92.61%. In addition, power-function type reaction kinetic equations were used to evaluate the effect of glycerol and NaOH concentrations and the reaction temperature on the oxidation of glycerol to lactic acid over 10% CuO/AC. The activation energy of the reaction is 134.39 kJ·mol-1, which is higher than that using single CuO as the catalyst. This indicates that CuO/AC is more temperature-sensitive than CuO and can probably achieve a higher lactic acid yield at high temperatures. At the same time, it is indicated that CuO supported on activated carbon can enhance the catalytic activity of CuO effectively.

Wet-Chemical Synthesis of TiO2/PVDF Membrane for Energy Applications

To satisfy the ever-increasing energy demands, it is of the utmost importance to develop electrochemical materials capable of producing and storing energy in a highly efficient manner. Titanium dioxide (TiO₂) has recently emerged as a promising choice in this field due to its non-toxicity, low cost, and eco-friendliness, in addition to its porosity, large surface area, good mechanical strength, and remarkable transport properties. Here, we present titanium dioxide nanoplates/polyvinylidene fluoride (TiO₂/PVDF) membranes prepared by a straightforward hydrothermal strategy and vacuum filtration process. The as-synthesized TiO₂/PVDF membrane was applied for energy storage applications. The fabricated TiO₂/PVDF membrane served as the negative electrode for supercapacitors (SCs). The electrochemical properties of a TiO₂/PVDF membrane were explored in an aqueous 6 M KOH electrolyte that exhibited good energy storage performance. Precisely, the TiO₂/PVDF membrane delivered a high specific capacitance of 283.74 F/g at 1 A/g and maintained capacitance retention of 91% after 8000 cycles. Thanks to the synergistic effect of TiO₂ and PVDF, the TiO₂/PVDF membrane provided superior electrochemical performance as an electrode for a supercapacitor. These superior properties will likely be used in next-generation energy storage technologies.

Multi-Functional Materials Based on Cu-Doped TiO2 Ceramic Fibers with Enhanced Pseudocapacitive Performances and Their Dielectric Characteristics

In this work, pure TiO2 and Cu (0.5, 1, 2%)-doped TiO2 composites prepared by electrospinning technique followed by calcination at 900 °C, and having high pseudocapacitive and dielectric characteristics were reported. These nanocomposites were characterized by scanning electron microscopy, X-ray diffraction, and dynamic water sorption vapor measurements. The structural characterization of these nanostructures highlighted good crystallinity including only the rutile phase. The electrochemical characteristics were investigated by cyclic voltammetry and galvanostatic charge-discharge measurements, which were performed in a KOH electrolyte solution. Among the Cu-doped TiO2 nanostructures that were prepared, the one containing 0.5% Cu exhibited superior electrochemical properties, including high specific gravimetric capacitance of 1183 F·g-1, specific capacitance of 664 F·g-1, energy density of 45.20 Wh·kg-1, high power density of 723.14 W·kg-1, and capacitance retention of about 94% after 100 cycles. The dielectric investigation shows good dielectric properties for all materials, where the dielectric constant and the dielectric loss decreased with the frequency increase. Thus, all the interconnected studies proved that these new materials show manifold ability and real applicative potential as pseudocapacitors and high-performance dielectrics. Future work and perspectives are anticipated for characterizing electrochemical and dielectric properties for materials including larger amounts of Cu dopant.

Construction of a Cu-Based Metal-Organic Framework by Employing a Mixed-Ligand Strategy and Its Facile Conversion into Nanofibrous CuO for Electrochemical Energy Storage Applications

Recently, metal-organic frameworks (MOFs) have been widely employed as a sacrificial template for the construction of nanostructured materials for a range of applications including energy storage. Herein, we report a facile mixed-ligand strategy for the synthesis of a Cu-MOF, [Cu₃(Azopy)₃(BTTC)₃(H₂O)₃·2H₂O]_n (where BTTC = 1,2,4,5-benzenetetracarboxylic acid and Azopy = 4,4'-azopyridine), via a slow-diffusion method at room temperature. X-ray analysis authenticates the two-dimensional (2D)-layered framework of Cu-MOF. Topologically, this 2D-layered structure is assigned as a 4-connected unimodal net with sql topology. Further, nanostructured CuO is obtained via a simple precipitation method by employing Cu-MOF as a precursor. After analysis of their physicochemical properties through various techniques, both materials are used as surface modifiers of glassy carbon electrodes for a comparative electrochemical study. The results reveal a superior charge storage performance of CuO (244.2 F g^-1 at a current density of 0.8 A g^-1) with a high rate capability compared to Cu-MOF. This observation paves the pathway for the strategic design of high-performing supercapacitor electrode materials.

An electrochemical immunosensor modified with titanium IV oxide/polyacrylonitrile nanofibers for the determination of a carcinoembryonic antigen

A highly sensitive electrochemical carcinoembryonic antigen immunosensor based on TiO₂np/polyacrylonitrile nanofibers electrospun on the surface of the discharged battery coal electrode.

High Entropy Oxides-A Cost-Effective Catalyst for the Growth of High Yield Carbon Nanotubes and Their Energy Applications

This report anticipates a thorough strategy for the utilization of high entropy oxide (HEO) nanoparticles (1) as a cost-effective catalyst for the growth of high yield carbon nanotubes (CNTs), resulting in HEO-CNT nanocomposites, and (2) the implementation of HEO-CNT nanocomposites for energy applications such as electrochemical capacitors (ECs). In the first step, HEO nanoparticles were synthesized by a simple sol-gel autocombustion method and then the as-synthesized HEO nanoparticles were ground and used as the catalyst for the growth of CNTs by chemical vapor deposition technique. The as-grown CNTs (HEO-CNT nanocomposite) exhibited unexpectedly high yield, a superior specific surface area of ∼151 m² g^-1, and encapsulation and diffusion of the catalyst throughout the HEO-CNT nanocomposite, providing remarkably high mechanical strength, which make them a promising candidate for energy applications. To study the electrochemical activity of the HEO-CNT nanocomposite, half-cell and full-cell ECs were assembled in different electrolytes. Stupendously, a complete 100% capacitance retention and a Coulombic efficiency up to 15 000 cycles were realized for the HEO-CNT nanocomposite-based full-cell EC assembled in the polyvinyl alcohol/H₂SO₄ hydrogel electrolyte. Additionally, a high specific capacitance value of 286.0 F g^-1 at a scan rate of 10 mV s^-1 for the HEO-CNT nanocomposite-based full-cell EC assembled in the [BMIM][TFSI] electrolyte with a wide potential window of 2.5 V is reported. Also, high energy density and power density of ∼217 W h kg^-1 and ∼24 521 W kg^-1, respectively, are reported. Furthermore, the HEO-CNT nanocomposite-based full-cell EC assembled in the [BMIM][TFSI] electrolyte can successfully light up a red light-emitting diode, demonstrating great potential of the HEO-CNT nanocomposite in the various energy applications.