In this work, symmetrical supercapacitors in the form of coin cell types were produced by using S-doped graphene powders. Sulfur doped graphene powders were prepared by cyclic voltammetry in different potential ranges for selective modification of powders by functional groups. S-Doped graphene powders were also characterized by spectroscopic, microscopic, and electrochemical methods. The formation of graphene layers was supported by scanning electron microscopic and Raman spectroscopic analyses. Functional groups formed on the graphene surface were identified by X-ray photoelectron spectroscopy. The electrodes formed with compositions consisting of binding material at 5%, conductive material at 5% and S-doped graphene powder at 90% were used in cyclic charge–discharge tests of the supercapacitors to determine the specific capacitance of them. The highest specific capacitance of the supercapacitors was determined as 176 F/g⁻¹, with a capacity loss of 5% at the end of 1000 cycles in A-SG3M.

The aim of this study was to synthesize the carbon-based nanomaterials and determine their hydrogen storage capacities. Carbon nanotubes (CNTs) were first synthesized by chemical vapor deposition (CVD) of acetylene (C₂H₂) on a magnesium oxide (MgO) powder impregnated with an iron nitrate (Fe(NO₃)₃·9H₂O) solution. The synthesis parameters were selected as the synthesis temperatures of 500 and 800°C, the iron content in the precursor of 5% and the synthesis time of 30 minutes. The synthesized material was purified by using HCl at 75°C for 15 hours. After synthesis of CNTs, the polyaniline-doped H₃BO₃ and BF₃ and composites were prepared by coagulation method. The synthesized CNTs and composites were characterized by transmission electron microscopy, FT-IR spectroscopy, Raman spectroscopy and thermogravimetric analyzer. The BET specific surface areas were obtained from the nitrogen adsorption isotherms at -196°C. The hydrogen storage capacities of these carbonaceous materials were measured using volumetric method. It was found that the hydrogen adsorption capacities were changed in the range between 0.44 and 3.67wt% at the liquid nitrogen temperature and gas pressure up to 100 bar.

Silica (SiO₂)-based materials are a promising alternative anode material due to their high specific capacity, abundance, safety, and environmental friendliness. However, the significant volume expansion and the formation of a solid electrolyte interphase (SEI) with electrolytes cause active lithium loss and result in poor Coulombic efficiency of SiO₂-based materials, which hinder their commercial applications. Therefore, pre-lithiation, a method of embedding extra lithium ions in the electrodes prior to cycling, is an effective approach to replenish the largely irreversible lithium loss during cycling and overcomes these challenges. In this study, carbon-coated silica (SiO₂@C) nano composite was synthesized via a sol–gel method and the beneficial impacts of using pre-lithiated SiO₂@C electrodes in coin cells were investigated. It is shown that the carbon coating onto the surface of the SiO₂ particles and the pre-lithiation method led to a distinct improvement in the overall capacity and Coulombic efficiency of the cells due to the pre-formed SEI and the presence of a lithium reservoir within the anode. Furthermore, the anodes exhibited excellent cycling stability and good rate capability up to 2 A g⁻¹.

Reactive sorbents for SO₂ removal from humidified flue gas were prepared from fly ash-Ca(OH)₂ mixtures using the pressure hydration technique. The fly ash samples were taken from three different coal-fired power plants in Turkey. The fly ash/Ca(OH)₂ weight ratio, hydration time, and temperature were varied during the sorbent preparation step. Effects of these variations on the physical properties of activated sorbents were investigated. A statistical design technique was applied by use of a two-level factorial design matrix to interpret experimental results. It was found that increasing the temperature and fly ash/Ca(OH)₂ weight ratio caused a decrease in the total surface area of sorbents. However, surface area values of sorbents were not generally affected by the hydration time variation. Finally, fly ash-Ca(OH)₂ sorbents prepared at the optimum hydration conditions were sulphated at 338 K with a synthetic gaseous mixture containing 5000 ppm SO₂ and 55% relative humidity.