Activated carbon and its hybrid composites with manganese (IV) oxide as effectual electrode materials for high performance supercapacitor

Exploring the diverse performance of nickel and cobalt spinel ferrite nanoparticles in hazardous pollutant removal and gas sensing performance

A simple sol-gel combustion process was employed for the creation of MFe2O4 (M=Ni, Co) nanoparticles. The synthesized nanoparticles, acting as both photocatalysts and gas sensors, were analyzed using various analytical techniques. MFe2O4 (M=Ni, Co) material improved the degradation of methylene blue (MB) under UV-light irradiation, serving as an enhanced electron transport medium. UV-vis studies demonstrated that NiFe2O4 achieved a 60% degradation, while CoFe2O4 nanostructure exhibited a 76% degradation efficacy in the MB dye removal process. Furthermore, MFe2O4 (M=Ni, Co) demonstrated chemosensitive-type sensor capabilities at ambient temperature. The sensor response and recovery times for CoFe2O4 at a concentration of 100 ppm were 15 and 20, respectively. Overall, the synthesis of MFe2O4 (M=Ni, Co) holds the potential to significantly improve the photocatalytic and gas sensing properties, particularly enhancing the performance of CoFe2O4. The observed enhancements make honey MFe2O4 (M=Ni, Co) a preferable choice for environmental remediation applications.

Applications of functionalized porous carbon from bio-waste of Alnus nepalensis in energy storage devices and industrial wastewater treatment

This research investigates the utility of functionalized porous carbon (FPC), derived from the waste wood of Alnus nepalensis. It demonstrates FPC's dual suitability as a versatile component for energy storage systems, specifically supercapacitors, and its impressive capacity to adsorb malachite green (MG) dye from industrial wastewater. The synthesis of FPC occurred through a controlled two-step process: initial activation of wood powder with H3PO4, followed by carbonization at 400 °C for 3 h in a tube furnace. To comprehensively evaluate the material's attributes, multiple analytical methods were employed: Brunauer-Emmet-Teller (BET) analysis, Transmission Electron Microscopy (TEM) imaging, X-ray Diffraction (XRD) analysis, Raman spectroscopy, and Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy. The prepared FPC exhibited desirable characteristics essential for achieving electrochemical performances and adsorption of dyes as well. TEM revealed voids within the material's structure, while BET confirmed high porosity with an active surface area of 1498 m2/g, a pore volume of 1.2 cm³/g, and a pore size of 4.6 nm featuring a harmonious presence of both micropores and mesopores. XRD and Raman spectroscopy confirmed FPC's amorphous state, and FTIR indicated oxygenated functional groups. As a supercapacitor electrode material, FPC demonstrated a specific capacitance of 156.3 F/g at 1A/g current density, an energy density of 5.1 Wh/Kg, a power density of 183.6 W/kg, and enduring cycling stability, retaining 98.4 % performance after 1000 charge-discharge cycles at 3A/g current density. In terms of dye adsorption, FPC exhibited remarkable efficiency. At a pH of 10.5 for MG dye, 0.030g of FPC displayed peak adsorption capacity, removing 95.6 % of 20 ppm MG within 2 min and an even more impressive 99.6 % within 6 min. These findings confirm FPC's potential from Alnus nepalensis as an outstanding supercapacitor electrode material and a rapid, efficient adsorbent for MG removal from industrial wastewater. This research suggests promising applications in energy storage and environmental remediation.

Electrochemical Performance of Chemically Activated Carbons from Sawdust as Supercapacitor Electrodes

Activated carbons (ACs) have been the most widespread carbon materials used in supercapacitors (SCs) due to their easy processing methods, good electrical conductivity, and abundant porosity. For the manufacture of electrodes, the obtained activated carbon based on sawdust (karagash and pine) was mixed with conductive carbon and polyvinylidene fluoride as a binder, in ratios of 75% activated carbon, 10% conductive carbon black, and 15% polyvinylidene fluoride (PVDF) in an N-methyl pyrrolidinone solution, to form a slurry and applied to a titanium foil. The total mass of each electrode was limited to vary from 2.0 to 4.0 mg. After that, the electrodes fitted with the separator and electrolyte solution were symmetrically assembled into sandwich-type cell construction. The carbon's electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge (CGD) studies in a two-electrode cell in 6M KOH. The CV and CGD measurements were realized at different scan rates (5-160 mV s^-1) and current densities (0.1-2.0 A g^-1) in the potential window of 1 V. ACs from KOH activation showed a high specific capacitance of 202 F g^-1 for karagash sawdust and 161 F g^-1 for pine sawdust at low mass loading of 1.15 mg cm^-2 and scan rate of 5 mV s^-1 in cyclic voltammetry test and 193 and 159 F g^-1 at a gravimetric current density of 0.1 A g^-1 in the galvanostatic charge-discharge test. The specific discharge capacitance is 177 and 131 F g^-1 at a current density of 2 A g^-1. Even at a relatively high scan rate of 160 mV s^-1, a decent specific capacitance of 147 F g^-1 and 114 F g^-1 was obtained, leading to high energy densities of 26.0 and 22.1 W h kg^-1 based on averaged electrode mass. Surface properties and the porous structure of the ACs were studied by scanning electron microscopy, energy-dispersive X-ray analysis, Raman spectroscopy, and the Brunauer-Emmett-Teller method.