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To achieve a higher energy density for the supercapacitor without degrading cycle stability, functionalization of biomass based-AC with oxygen-containing groups was applied. Nanostructured carbon materials were produced from barley straw biomass waste using the activation-functionalization by FeCl3 and urea via the pyrolysis method in a tubular reactor at 900 °C. The electrode made up of carbon BCF-U in the three-electrode cell in aqueous KOH electrolyte showed high-specific capacitance of 515 F g–1 at current density of 2 A g−1 and in aqueous Na2SO4 electrolyte the capacitance of 379 F g−1 at 3 A g−1. The BCF-U electrode showed cycling stability, retaining more than 99% capacitance after 5000 cycles in 1 M Na2SO4 electrolyte. The fabricated symmetric supercapacitor device with carbon BCF-U showed a high-energy density of 10.7 Wh kg–1 and a power density of 720 W kg−1 in aqueous 6 M KOH. Different characterizations were carried out to show that the functional group and morphological features of the activated carbon were closely related to the superior capacitive performance by enhancing diffusion of electrolyte ions. The analysis proved the formation of graphitic nature with mixed micro- and mesoporous textures in addition to carbon nanotube, carbon nano rod, and graphene. These unique features make synthetic activated and functionalized samples possess good adsorption capacity for electrical double layer capacitors. The results demonstrate that nanostructured carbon materials derived from a low-cost biomass waste can serve as an economical carbon feedstock for production of high-performance electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

The exploration of the chiral configurations of enantiomers represents a highly intriguing realm of scientific inquiry due to the distinct roles played by each enantiomer (D and L) in chemical reactions and their practical utilities. This study introduces a pioneering analytical methodology, termed fast Fourier transform capacitance voltammetry (FFT-CPV), in conjunction with principal component analysis (PCA), for the identification and quantification of the chiral forms of tartaric acid (TA), serving as a representative model system for materials exhibiting pronounced chiral characteristics. The proposed methodology relies on the principle of chirality, wherein the capacitance signal generated by the adsorption of D-TA and L-TA onto the surface of a platinum electrode (Pt-electrode) in an acidic solution is harnessed. The capacitance voltammograms were meticulously recorded under optimized experimental conditions. To compile the final dataset for the analyte, the average of the FFT capacitance voltammograms of the acidic solution (without the presence of the analyte) was subtracted from those containing the analyte. A distinct arrangement was obtained by employing PCA as a linear data transformation method, representing D-TA and L-TA in a two/three-dimensional space. The outcomes of the study reveal the successful detection of the two chiral forms of TA with a considerable degree of precision and reproducibility. Moreover, the proposed method facilitated the establishment of two linear response ranges for the concentration values of each enantiomer, spanning from 1 to 20 µM, and 50 to 500 µM. The respective detection limits were also determined to be 0.4 µM for L-TA and 1.3 µM for D-TA. These findings underscore the satisfactory sensitivity and efficiency of the proposed method in both qualitative and quantitative assessments of the chiral forms of TA. [ABSTRACT FROM AUTHOR]

Since the importance of sulfonamide compound determinations, in this work, Sulfadiazine (SDZ), one of the significant sulfonamide antibiotics was electrochemically studied. SDZ is listed as world health organization (WHO) crucial medications in treatment of basic health system. A new graphene based nano-composite electrode was made and used for the electrochemical studies of some sulfondiamides. Electrochemical behavior of the compounds was initially investigated on bare and modified carbon paste electrodes using cyclic voltammetry (CV). The modifiers include Ceria (CeO) NPs, reduced graphene oxide (RGO) and RGO decorated CeO NPs. The composition of 5% RGO decorated CeO nanoparticles, 65% graphite, and 30% paraffin presented the best redox response for Sulfadiazine. Then, the nano-composite electrode was applied for SDZ measurement by fast Fourier transform square wave voltammetry (FFTSWV) on the proposed nano-composite electrode. Response linear range was obtained for 3-10 µM (R = 0.9956) and 30-1000 µM (R = 0.9948) of SDZ concentration, respectively, with LOD of 0.17 µM and LOQ of 3 µM. Finally, SDZ content in some pharmaceutical formulations were effectively analyzed by the proposed method and acceptable relative error of 4.6% was achieved. [ABSTRACT FROM AUTHOR]