Synthetic Strategies of Carbon Nanobelts and Related Belt-Shaped Polycyclic Aromatic Hydrocarbons

The development of carbon nanobelts and related belt-shaped polycyclic aromatic hydrocarbons has gained momentum in recent years. This Minireview focuses on the synthetic strategies used in constructing these aesthetically appealing molecular nanocarbons. Examples of carbon nanobelts and related belt-shaped polycyclic aromatic hydrocarbons reported in recent years as well as some representative synthetic attempts in earlier times are discussed.     

Hierarchical Mn3O4 Anchored on 3D Graphene Aerogels via C−O−Mn Linkage with Superior Electrochemical Performance for Flexible Asymmetric Supercapacitor

Flexible asymmetric supercapacitors are more appealing in flexible electronics because of high power density, wide cell voltage, and higher energy density than symmetric supercapacitors in aqueous electrolyte. In virtues of excellent conductivity, rich porous structure and interconnected honeycomb structure, three dimensional graphene aerogels show great potential as electrode in asymmetric supercapacitors. However, graphene aerogels are rarely used in flexible asymmetric supercapacitors because of easily re-stacking of graphene sheets, resulting in low electrochemical activity. Herein, flower-like hierarchical Mn₃O₄ and carbon nanohorns are incorporated into three dimensional graphene aerogels to restrain the stack of graphene sheets, and are applied as the positive and negative electrode for asymmetric supercapacitors devices, respectively. Besides, a strong chemical coupling between Mn₃O₄ and graphene via the C-O-Mn linkage is constructed and can provide a good electron-transport pathway during cycles. Consequently, the asymmetric supercapacitor device shows high rate cycle stability (87.8 % after 5000 cycles) and achieves a high energy density of 17.4 μWh cm⁻² with power density of 14.1 mW cm⁻² (156.7 mW cm⁻³) at 1.4 V.     

Mussel-inspired polydopamine functionalized recyclable coconut shell derived carbon nanocomposites for efficient adsorption of methylene blue

Relatively cheap or at no cost, easily available, renewable agricultural waste has been given a new purpose. Using coconut shells as the raw material, and being obtained from agricultural, industry by-products, or even waste materials were used as carbon resource. Acid etching coconut shells carbon (AC) rendered micro/nanoscale hierarchical structures and made the surface available for further modification. Then, the surface of acidified coconut shell carbon was engineered via mussel inspired chemistry. The polydopamine functionalized AC composites (AC-PDA) were applied for efficient removal of methylene blue (MB) dye. Further, the surface morphology, and chemical structure were evaluated by means of scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). Through the combination of acid etching and mussel inspired chemistry, organic functional groups can be successfully introduced onto the surface of the coconut shells carbon. The improvement of adsorption capacity of AC-PDA compared with AC is probably due to the increased number of active binding sites resulting from surface modification and formation of new functional groups.     

Microwave Synthesized In2S3@CNTs with Excellent Properties inLithium‐Ion Battery and Electromagnetic Wave Absorption

The three‐dimensional nanoflower‐like β‐In₂S₃ composited with carbon nanotubes (CNTs) has been synthesized by a single mode microwave‐assisted hydrothermal technique. The In₂S₃ and CNTs nanocomposites (In₂S₃@CNTs) were investigated as the anode materials of lithium batteries (LIBs) and the electromagnetic wave absorption materials. For LIBs applications, the In₂S₃@CNTs nanocomposite exhibited excellent cycling stability with a high reversible charge capacity of 575 mA⋅h⋅g^–1 after 300 cycles at 0.5 A⋅g^–1. In addition, the In₂S₃@CNTs used as electromagnetic wave absorber displayed a maximum reflection loss of –42.75 dB at 11.96 GHz with a thickness of 1.55 mm.     

New Insight into the EC’ Mechanism of Uric Acid Regeneration in the Presence of Ascorbic Acid on a Poly(3,4‐ethylenedioxithiophene) Modified Gold Electrode

A gold electrode surface was functionalized by means of an electropolymerized conductive poly(3,4‐ethylenedioxythiophene) (PEDOT) organic layer. This modified electrode was used for the electrochemical detection of ascorbic (AA) and uric (UA) acids in an aqueous mixture with a selectivity around 340 mV. The electrochemical reactions kinetics were limited by AA diffusion and UA adsorption at the electrode surface, respectively. Following a previous study ([Electrochem Comm. 2011 , 13, 423–425]) cyclic voltammetry was used to provide a better understanding of the EC’ mechanism of regeneration of UA by AA. Experiments particularly showed that allantoin (i. e. the final product of UA oxidation) is not actually involved in the synergic mechanism but rather the oxidized UA product diimine which is adsorbed at the electrode surface.     

The effect of wave characteristics on rivulet formation in heated liquid films

Formation of rivulets on the surface of non-isothermal water film falling vertically over the heaters with different sizes and boundary conditions was studied experimentally. The distances between rivulets were measured depending on Reynolds number, heat flux density and film path (a distance between the lower edge of a film-former nozzle and the measurement point of film flow characteristics). The breakdown of solitary waves at liquid film heating was revealed. Four zones of film path influence on rivulet formation were distinguished.     

Search for carbon stars and DZ white dwarfs in SDSS spectra survey through machine learning

Carbon stars and DZ white dwarfs are two types of rare objects in the Galaxy.In this paper,we have applied the label propagation algorithm to search for these two types of stars from Data Release Eight(DR8)of the Sloan Digital Sky Survey(SDSS),which is verified to be efcient by calculating precision and recall.From nearly two million spectra including stars,galaxies and QSOs,we have found 260 new carbon stars in which 96 stars have been identified as dwarfs and 7 identified as giants,and 11 composition spectrum systems(each of them consists of a white dwarf and a carbon star).Similarly,using the label propagation method,we have obtained 29 new DZ white dwarfs from SDSS DR8.Compared with PCA reconstructed spectra,the 29 findings are typical DZ white dwarfs.We have also investigated their proper motions by comparing them with proper motion distribution of 9,374 white dwarfs,and found that they satisfy the current observed white dwarfs by SDSS generally have large proper motions.In addition,we have estimated their efective temperatures by fitting the polynomial relationship between efective temperature and g-r color of known DZ white dwarfs,and found 12 of the 29 new DZ white dwarfs are cool,in which nine are between 6,000 K and 6,600 K,and three are below 6,000 K.     

A Scalable Process for Production of Single-walled Carbon Nanotubes (SWNTs) by Catalytic Disproportionation of CO on a Solid Catalyst

Existing single-walled carbon nanotube synthesis methods are not easily scalable, operate under severe conditions, and involve high capital and operating costs. The current cost of SWNT is exceedingly high. A catalytic method of synthesis has been developed that has shown potential advantages over the existing methods. This method is based on a catalyst formulation that inhibits the formation of undesired forms of carbon; it can be scaled-up and may result in lower production costs.     

Adsorption isotherms and kinetics of methylene blue on a low-cost adsorbent recovered from a spent catalyst of vinyl acetate synthesis

A regenerated activated carbon used as catalyst support in the synthesis of vinyl acetate has been tested as a low-cost adsorbent for the removal of dyes. After a thorough textural characterization of the regenerated activated carbon, its adsorption isotherms and kinetics were determined using methylene blue as model compound at different initial concentrations. Both Langmuir and Freundlich isotherm models were developed and then compared. It was found that the equilibrium data were best represented by the Langmuir isotherm model. The kinetic data were fitted to pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and it was found that the best fitting corresponded to the pseudo-second-order kinetic model. The results showed that this novel adsorbent had a high adsorption capacity, making it suitable for use in the treatment of methylene blue enriched wastewater.     

Heterogeneous adsorption and catalytic oxidation of benzene, toluene and xylene over spent and chemically regenerated platinum catalyst supported on activated carbon

The heterogeneous adsorption and catalytic oxidation of benzene, toluene and o-xylene (BTX) over the spent platinum catalyst supported on activated carbon (Pt/AC) as well as the chemically treated spent catalysts were studied to understand their catalytic and adsorption activities. Sulfuric aqueous acid solution (0.1N, H₂SO₄) was used to regenerate the spent Pt/AC catalyst. The physico-chemical properties of the catalysts in the spent and chemically treated states were analyzed by using nitrogen adsorption-desorption isotherm and elemental analysis (EDX). The gravimetric adsorption and the light-off curve analysis were employed to study the BTX adsorption and oxidation on the spent catalyst and its modified Pt/AC catalysts. The experimental results indicate that the spent Pt/AC catalyst treated with the H₂SO₄ aqueous solution has a higher toluene adsorption and conversion ability than that of the spent Pt/AC catalyst. A further studies of H₂SO₄ treated Pt/AC catalyst on their catalytic and heterogeneous adsorption behaviours for BTX revealed that the activity of the H₂SO₄ treated Pt/AC catalyst follows the sequence of benzene > toluene > o-xylene. The adsorption equilibrium isotherms of BTX on the H₂SO₄ treated Pt/AC were measured at different temperatures ranging from 120 to 180 °C. To correlate the equilibrium data and evaluate their adsorption affinity for BTX, the two sites localized Langmuir (L2m) isotherm model was employed. The heterogeneous surface feature of the H₂SO₄ treated Pt/AC was described in detail with the information obtained from the results of isosteric enthalpy of adsorption and adsorption energy distributions. Furthermore, the activity of H₂SO₄ treated Pt/AC about BTX was found to be directly related to the Henry's constant, isosteric enthalpy of adsorption and adsorption energy distribution functions.