DFT Based Material Computations of Metal-doped and Pure Carbon Nanodots for Examining their Enhancement of Sulfur Dioxide Adsorption

Carbon nanodots, one of the last members of the nanocarbon family, show superior properties, such as low-cost production, good conductivity, and optical properties, nontoxic behavior, high biocompatibility, and eco-friendly nature. Understanding the effect of metal doping on the modification of the electronic structure of carbon nanodots is critical for enlarging its potential applications. In the present study, in terms of structural, energetic, and electronic analyses, X-doped carbon nanodot structures (X = B, N, Si, Al, Co, Au, Pd, and Pt) and their SO2 adsorption abilities were examined comprehensively by employing DFT. Results depict that embedding the heavy impurity metals (Pd, Pt) to the nanodot structures does not improve the SO2 sensing ability of carbon nanodot materials relatively. However, the doping of the low concentrated metals to the carbon nanodots may be one of the best ways for enhancing the SO2 trapping ability of the carbon nanodot materials since the calculated results having high adsorption energy values indicate SO2 gas molecule is easily adsorbed on the surface of doped carbon nanodots. This means higher adsorption capability compared to pure ones. Thus, it is suggested that the doped carbon nanodots consisting of B, Si, and N impurity atoms may be good candidates for effective SO2 sensing (adsorptions).

Electron impact dissociation of CO2 (a review)

Based on a detailed analysis and generalization of the results of calculations of the energy spectrum of electrons using different models in gas discharges in pure carbon dioxide CO2 and in mixtures containing CO2 , the rate constant of CO2 dissociation by electron impact in a gas discharge of direct current at atmospheric pressure is found. It is shown that, at values of the reduced electric field from 55 Td to 100 Td, the predominant mechanism of decomposition of the CO2 molecule is the collision of CO2 molecules with electrons. An expression is obtained for calculating the rate constant of CO2 dissociation by electron impact as a function of the reduced electric field.

Features of Pyrolysis of Plant Biomass at Excessive Pressure

The paper describes methods for producing charcoal (highly porous carbon materials) based on plant (wood) raw materials, and the equipment used to implement these processes, the use of activated carbons. The paper describes results of an experimental study of the effect of pressure on the formation of charcoal in the pyrolysis of birch chips. The experimental investigation was carried out at pressures of 0.1, 0.3, 0.5, 0.7 MPa. To investigate the effect of pressure on the pyrolysis process, a laboratory bench was designed and constructed. It was found that increasing the pressure from 0.1 MPa to 0.7 MPa increases the yield of charcoal from 25.1 to 32.4% by weight (relative to the dry weight of the starting material) and the carbon content from 89.1% by weight at 0.1 MPa to 96.4% by weight at 0.7 MPa. The calorific value of charcoal decreases from 34.86 MJ/kg at a pressure of 0.1 MPa to 30.23 MJ/kg at a pressure of 0.7 MPa. This is due to the release of oxygen-containing components, which have a higher calorific value than pure carbon, from the porous coal structure. Reduction of the charcoal heat combustion with a decrease in the amount of oxygen-containing components confirms conclusion that their calorific value exceeds the calorific value of pure carbon.

Looking for the missing link in the evolution of black inks

In the transition from carbon to iron-gall inks, the two documents from the Egyptian Museum and Papyrus Collection in Berlin with shelfmarks P 13500 and P 13501 discussed in this work present an important case. Their inks appear brownish, although they date back to the fourth and third century BCE, when carbon inks are believed to have been commonly if not exclusively used. Using imaging micro-X-ray fluorescence and infrared reflectography, we discovered that the inks in both documents contain a significant amount of copper in addition to carbon. Comparing the extant recipes for black writing inks and the experimental evidence, we suggest that these inks are a transition between the pure carbon and the iron-gall inks. Such inks may have been quite common before the production of iron-gall ink was clearly understood and established.

Flexible Thin Carbon Nanotube Web Film for Curved Heating Elements Under High Temperature Conditions

Heating elements need a rapid heating property and long-term cycle stability when subjected to extreme temperatures. Carbon nanotube-based films can be used as ideal heating units owing to their superior electrical and thermal properties. However, carbon nanotube polymer composites are not appropriate for extreme conditions such as high temperatures (300 °C) due to the poor thermal stability of the polymer matrix. In this study, we fabricated a carbon nanotube web film, comprising heating elements consisting of pure carbon nanotubes, through the direct spinning method. The carbon nanotube web film has a microscale thickness. The carbon nanotube web film showed flexibility at high temperatures, while a fracture occurred in the case of the carbon nanotube polymer composite. We conducted electrical heating experiments on the curved carbon nanotube web film to observe the heating uniformity and flexibility. The heating test is conducted on various curved form heaters. The carbon nanotube web film showed rapid heating properties and a uniform heat distribution (temperature departure of less than 3%) without thermal aggregation. The curved heating units can be utilized in various applications such as functional clothes and de-icing systems having curved surfaces.

Investigation of Optical Properties for N and F Doped Triangular Shaped Carbon Molecules

Optical properties of N and F doping triangular shaped carbon molecules have been investigated in theory and experiment. The theoretical results showed that carbon molecules with impurity F and Cl have the same characters with pure carbon. Doping N into pure carbon molecule would change the optical rotation at 589nm. For doping N replacing hydrogen atom structures (N-doping 1 and N-doping 2 molecules), the absorption spectra of them are similar to pure carbon molecule. However, for molecules with impurity N atom in benzene ring (N-doping 3 and N-doping 4 molecules), the peaks of wavelength of absorption spectra shift to long wavelength compared to that of pure carbon molecule. Moreover, the delocalization of molecular orbital (MO) is different from pure carbon molecule, which is caused by the impurity N changing the electrons distribution of benzene ring. We have calculated 3 without H and 4 without H molecules which are removing hydrogen atom in nitrogen atom from N-doping 3 and 4. 3 without H and 4 without H molecules have similar optical properties with pure carbon molecule. The results testified that the impurity N and F would not change the optical properties of carbon molecule if impurity did not change the delocalization of all benzene rings.

A computable general equilibrium analysis of environmental tax reform in Japan with a forward-looking dynamic model

The Japanese government plans to reduce greenhouse gas emissions by 80% by 2050. However, it is not yet clear which policy measures the government will adopt to achieve this goal. In this regard, environmental tax reform, which is the combination of carbon regulation and the reduction of existing distortionary taxes, has attracted much attention. This paper examines the effects of an environmental tax reform in Japan. Using a dynamic computable general equilibrium (CGE) model, we analyze the quantitative impacts of an environmental tax reform and clarify which types of environmental tax reform are the most desirable. In the simulation, we introduce a carbon tax and consider the following four scenarios for the use of the carbon tax revenue: (1) a lump-sum rebate to the household, (2) a cut in income taxes, (3) a cut in corporate taxes and (4) a cut in consumption taxes. The first scenario is a pure carbon tax, and the other three scenarios are types of environmental tax reform. Our CGE simulation shows that (1) environmental tax reform tends to generate more desirable impacts than the pure carbon tax and that (2) the strong double dividend is obtained in some cases. In particular, we show that a cut in corporate taxes leads to the most desirable policy in terms of GDP and national income.