The objective of this work is to develop a cost-effective carbonaceous CO2 adsorbent. N-doped porous carbon (NDC) with nanopore size was synthesized by KOH activation of nano polyaniline (PANI). PANI synthesized in this work has thin nanofibrillar morphology with different lengths and diameters. The activation process was carried out at 800 ° C with KOH/precursor ratio of 2. This adsorbent of carbon exhibits high CO2 adsorption capacity of 1. 9 mmol/g at 25 ° C under atmospheric pressure. The morphology of PNCs is investigated through different technical methods, such as scanning electron microscopy (SEM), N2 adsorption isotherm at 77 K and Fourier transform infrared spectroscopy (FTIR). The CO2 adsorption experiments were done at three different temperatures (298, 308, and 318 K) and pressure up to 10 bar, and correlated with the Langmuir, Freundlich, and Sips models. The Sips isotherm model presented the best fit to the experimental data. Small values of isosteric heat of adsorption were evaluated based on Clausius-Clapeyron equation showed the physical nature of adsorption mechanism. The high amount of CO2 capture by nanopore size NDC renders it as a promising carrier for practical applications such as gas separation.

In this study, the oxidation of benzyl alcohols to aldehydes using nitrogen-doped mesoporous carbon spheres as a heterogeneous catalyst was investigated for the first time. Initially, Stöber method was used to synthesize silicate-polyaminophenol-formaldehyde structures using tetraethyl orthosilicate, 3-aminophenol, and ethylene diamine as silica templates, carbon precursors, and regulators, respectively, in an aqueous-ethanol medium with ammonia as a catalyst. The synthesized structure transformed into N-doped carbon-silica structure during annealing under inert gas. N-doped mesoporous carbon spheres were formed after etching the silica network with sodium hydroxide. The amount of nitrogen loading was determined by elemental analysis, and its amount was determined to be 8.00 wt%. The surface area determined by nitrogen absorption and desorption analysis is 1186 m2g-1. Based on FE-SEM images, the average particle size is about 300 nm. Aqueous benzyl alcohol oxidation was carried out using the synthesized catalyst to investigate its catalytic activity. A study has been conducted to assess the effects of temperature, time, oxidant type, and catalyst amount on reaction yield as well as catalyst recycling potential. The synthesized catalyst shows remarkable catalytic performance for benzyl alcohol oxidation, achieving high yield (over 88% within 6 h) and selectivity (99%). The catalytic activity did not change significantly after four recycling cycles.

DLC films were deposited on Si substrates using direct ion beam deposition method, followed by investigating the influence of O2 and N2 doping on their electrical and structural properties. The films were doped with oxygen and nitrogen under flow rates of 5 and 40 sccm (standard cubic centimeters per minute). The structure of the films was studied by Raman spectroscopy.  Result showed that by increasing oxygen incorporation, sp2 content decreases, sp3 content increases, and the C-C bonding loses its order. As the size of the sp2-rich cluster increased with N2 content, the disorder in the DLC samples decreased, leading to a decrease in the FWHM of the G peak. The water contact angle measurement showed that an increase in oxygen flow ratio results in a decrease in contact angle from 82.9° ± 2.1° to 50° ± 3°. With increasing nitrogen flow rate from 5 to 40, the contact angle of DLC thin films increased from 78° to 110°.

In this research, we synthesized nitrogen-doped carbon dots using three isomers of phenylenediamine (o-PDA, m-PDA, and p-PDA) as nitrogen sources and citric acid as the carbon source. We selected these isomers to study their effect on surface chemistry and optical characteristics. The carbon dots produced contain nitrogen, carboxyl, and hydroxyl groups that interact with the environment and exhibit a change in emission based on the surroundings. Our team conducted an in-depth analysis of the fluorescence emissions exhibited by carbon dots. The study involved examining the behavior of these particles in solvents with varying degrees of polarity, ranging from weakly polar CHCl3 to strongly polar protic water and a binary mixture of H2O-Acetone. The results of the study provide valuable insights that could contribute to advancing our understanding of carbon dots properties. Interestingly, with increasing the water content of organic solvents, the carbon dots changed their fluorescence color from blue to green. We utilized the Lippert-Mataga plot to exhibit a direct correlation between polarity and carbon dots emission wavelength, which demonstrated a positive linear trend as the polarity was increased. The slope for the three isomers was ∆µ=38959, 42115, 2346.5 for O-CD, M-CD and P-CD, respectively. Our results confirm that the polarity of CDs in ground state is less than exited state (μg < μex). This study helps us understand the solvent-dependent behavior of nitrogen-doped carbon dots, particularly their solvent polarity characteristics. We also analyzed the optical properties of M-CD and found a linear response to the polarity and water content of the organic solvent, which suggests the possibility of M-CD as a humidity sensor for detecting water in organic solvents.

In this study, the nitrogen-doped carbon quantum dots were synthesized via microwave method using citric acid and urea precursors in a homogeneous aqueous solution. A centrifuge machine was used to eliminate large particles from the samples and to sort nanosized particles with variable centrifugal forces. X-ray diffraction pattern was obtained in order to study the formation of crystalline structure type of the sample and the size of crystallite. The broadening of peak indicated the nanosized formation of synthesized particles. Optical properties of the samples were examined by ultraviolet-visible and photoluminescence spectrometers. The absorption peaks wavelengths depended on particle sizes and had blue shift by decreasing of particle sizes. The Tauc plot indicated that energy gap increased from 2. 39 eV to 2. 62 eV with decreasing particle size. Emission peaks of nitrogen-doped carbon quantum dots, under the excitation of ultraviolet light, had fluorescence radiations in the visible spectral region of the green-blue.

In this study, nitrogen-doped porous carbon was prepared using a nitrogen containing polymer (polyaniline) as a precursor with KOH activation at activation temperature of 800° C. The porous structure of polyaniline and synthesized adsorbent were analyzed with atomic force microscopy (AFM), N2 adsorption-desorption isotherm, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The adsorption of CO2 and N2 by nitrogen-doped porous carbon were measured and correlated Sips model. The BET surface area and CO2 adsorption of prepared adsorbent (at 298K and 1ba) was achieved 723 m2/g and 1. 90 mmol/g, respectively. The selectivity of CO2 over N2 (CO2: N2 =50: 50, 298 K, 1 bar), predicted by the ideal adsorbed solution theory (IAST) model, was achieved 3. 02. The isostrict heat of adsorption was calculated by using Clausius-Clapiron equation and the results confirmed the exothermic nature of adsorption for both gases. Also, the higher value of heat of adsorption CO2 than N2, showed the stronger interaction between CO2 molecules with the nitrogen-doped porous carbon surface. Results obtained from gas adsorption and heat of adsorption proved the suitability of nitrogen-doped carbon in cyclic processes such as the PSA process.