Nitrogen-doped graphene oxide sheets (N-GOs) are prepared by employing N-containing polymers such as polypyrrole, polyaniline, and copolymer (polypyrrole-polyaniline) doped with acids such as HCl, H2SO4, and C6H5-SO3-K, which are activated using different concentrations of KOH and carbonized at 650 °C; characterized using SEM, TEM, BET, TGA-DSC, XRD, and XPS; and employed for the removal of environmental pollutant CO2. The porosity of the N-GOs obtained were found to be in the range 1–3.5 nm when the KOH employed was in the ratio of 1:4, and the XRD confirmed the formation of the layered like structure. However, when the KOH employed was in the ratio of 1:2, the pore diameter was found to be in the range of 50–200 nm. The SEM and TEM analysis reveal the porosity and sheet-like structure of the products obtained. The nitrogen-doped graphene oxide sheets (N-GOs) prepared by employing polypyrrole doped with C6H5-SO3-K were found to possess a high surface area of 2870 m2/g. The N-GOs displayed excellent CO2 capture property with the N-GOs; PPy/Ar-1 displayed ~1.36 mmol/g. The precursor employed, the dopant used, and the activation process were found to affect the adsorption property of the N-GOs obtained. The preparation procedure is simple and favourable for the synthesis of N-GOs for their application as adsorbents in greenhouse gas removal and capture.

A new approach has been developed for the preconcentration of analytes from solution using nanoscavengers; monodisperse functionalised particles of sub-micron dimensions, that can be suspended as a quasi-stable sol in an aqueous solution, and quantitatively recovered with the analyte by conventional filtration. No external agitation of the sample is required as the particles move naturally through the sample by Brownian motion, convection and sedimentation. By careful choice and control of their particle size and surface chemistries, nanoscavengers can be designed to suit a number of different analytical problems. Surface modification of these nanometre-sized particles, through the grafting of complexing or partitioning functional groups, can produce nanoscavengers having affinities for specific analytes and operating through a wide range of mechanisms from covalent bonding to hydrophobic interaction. The approach is illustrated by the development of an extraction-based preconcentration of metals from solution that employs sub-micron Stöber-type silica spheres, the surfaces of which have been modified using chelating diamine and dithiocarbamate groups. The concept has potentially widespread applicability as it is neither limited to metal extractions, nor to the use of silica-based nanoscavengers. Minimal involvement of organic solvents make nanoscavengers a potentially environmentally benign ("green") alternative to many conventional solvent extraction techniques.

High surface area mesoporous polyaniline (M-PANI) films can be produced on the surface of glassy carbon electrodes by the electrochemical polymerization from a composite made by mixing a Brij 98 surfactant with a water solution of aniline and sulfuric acid. The surfactant serves as a structure directing agent. When the quantity of Brij 98 in the composite was 45% by weight, it formed a hexagonal phase that comprises a template of cylinders arranged on a hexagonal lattice with a hydrophilic core. The aniline monomer infiltrated the core of the templates. When the potential of the glassy carbon electrode was cycled, the polymerization occurred inside the hollow core and cast it with the PANI film. Subsequently, the Brij 98 template was removed by a thorough washing with water to produce a well-ordered M-PANI film. The structure and the surface morphology of the M-PANI films were fully characterized by a scanning electron microscope and a transmission electron microscope. The electrochemical capacitance properties were investigated using electrochemical techniques, e.g., cyclic voltammetry, galvanostatic cycling and electrochemical impedance. The data showed a significant increase in the specific capacitance (as high as 532 F g −1 ) of the M-PANI films when compared with a non M-PANI electrode, which delivered a specific capacitance of 228 F g Supercapacitors, also known as electrochemical capacitors, have attracted immense attention as one type of efficient energy storage device because of their unique capability to store and release the charge at a very high rate.1,2 Supercapacitors store electrical charges at the interface between high surface area electrodes and liquid electrolytes. The energy stored in supercapacitors comes from the non-faradaic current due to charging of the electrical double layer as well as the pseudocapacitance produced by the faradaic current, which is caused by oxidation-reduction processes that take place at the surface of the electroactive materials.3-5 Therefore, supercapacitors could store capacitances several orders of magnitude higher than conventional capacitors while still maintaining the unique advantage of a high power density and exhibiting excellent reversibility with a long life cycle. 6,7 Many materials have been used to fabricate supercapacitor electrodes, such as carbon 8 and metal oxides, e.g., RuO 2 and NiO x . 9,10Also, conducting polymers of polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene), and polythiophene are widely employed as electrode materials in supercapacitor applications. 11,12 Conducting polymers mainly store energy through a faradaic current resulting from the transfer of charge between electrode and electrolyte (pseudocapacitors). The charge-transfer process is usually accompanied by electrosorption, oxidation-reduction reactions, and intercalation processes.13 When oxidation occurs, ions are transferred to the polymer backbone and, in case of reduction, the ions are released back into the solution; therefore, the charge-discharge process in con...

No abstract

No abstract

Various carbon dioxide (CO2) capture materials and processes have been developed in recent years. The absorption-based capturing process is the most significant among other processes, which is widely recognized because of its effectiveness. CO2 can be used as a feedstock for the production of valuable chemicals, which will assist in alleviating the issues caused by excessive CO2 levels in the atmosphere. However, the interaction of carbon dioxide with other substances is laborious because carbon dioxide is dynamically relatively stable. Therefore, there is a need to develop types of catalysts that can break the bond in CO2 and thus be used as feedstock to produce materials of economic value. Metal oxide-based processes that convert carbon dioxide into other compounds have recently attracted attention. Metal oxides play a pivotal role in CO2 hydrogenation, as they provide additional advantages, such as selectivity and energy efficiency. This review provides an overview of the types of metal oxides and their use for carbon dioxide adsorption and conversion applications, allowing researchers to take advantage of this information in order to develop new catalysts or methods for preparing catalysts to obtain materials of economic value.

Synthesis, crystallographic data, and theoretical calculations of HC•8SbF 6 as well as photoinduced IET data. This material is available free of charge via the Internet at http://pubs.acs.org.

Increased levels of carbon dioxide have revolutionised the Earth; higher temperatures, melting icecaps, and flooding are now more prevalent. Fortunately, renewable energy mitigates this problem by making up 20% of human energy needs. However, from a “green environment” perspective, can carbon dioxide emissions in the atmosphere be reduced and eliminated? The carbon economic circle is an ideal solution to this problem, as it enables us to store, use, and remove carbon dioxide. This research introduces the circular carbon economy (CCE) and addresses its economic importance. Additionally, the paper discusses carbon capture and storage (CCS), and the utilisation of CO2. Furthermore, it explains current technologies and their future applications on environmental impact, CO2 capture, utilisation, and storage (CCUS). Various opinions on the best way to achieve zero carbon emissions and on CO2 applications and their economic impact are also discussed. The circular carbon economy can be achieved through a highly transparent global administration that is supportive of advanced technologies that contribute to the efficient utilisation of energy sources. This global administration must also provide facilities to modernise and develop factories and power stations, based on emission-reducing technologies. Monitoring emissions in countries through a global monitoring network system, based on actual field measurements, linked to a worldwide database allows all stakeholders to track the change in greenhouse gas emissions. The process of sequestering carbon dioxide in the ocean is affected by the support for technologies and industries that adopt the principle of carbon recycling in order to maintain the balance. This includes supporting initiatives that contribute to increasing vegetation cover and preserving oceans from pollutants, especially chemicals and radioactive pollutants, which will undoubtedly affect the process of sequestering carbon dioxide in the oceans, and this will contribute significantly to maintaining carbon dioxide at acceptable levels.