The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

Role of nanomaterials in water treatment applications: a review.

Water pollution is a global problem threatening the entire biosphere and affecting the life of many millions of people around the world. Not only is water pollution one of the foremost global risk factors for illness, diseases and death, but it also contributes to the continuous reduction of the available drinkable water worldwide. Delivering valuable solutions, which are easy to implement and affordable, often remains a challenge. Here we review the current state-of-the-art of available technologies for water purification and discuss their field of application for heavy metal ion removal, as heavy metal ions are the most harmful and widespread contaminants. We consider each technology in the context of sustainability, a largely neglected key factor, which may actually play a pivotal role in the implementation of each technology in real applications, and we introduce a compact index, the Ranking Efficiency Product (REP), to evaluate the efficiency and ease of implementation of the various technologies in this broader perspective. Emerging technologies, for which a detailed quantitative analysis and assessment is not yet possible according to this methodology, either due to scarcity or inhomogeneity of data, are discussed in the final part of the manuscript.

Sustainable technologies for water purification from heavy metals: review and analysis

Functionalization of carbon nanomaterials for advanced polymer nanocomposites: A comparison study between CNT and graphene

During the last decade, two-dimensional materials (2DMs) have attracted great attention due to their unique chemical and physical properties, which make them appealing platforms for diverse applications in opto-electronic devices, energy generation and storage, and sensing. Among their various extraordinary properties, 2DMs possess high surface area-to-volume ratios and ultra-high surface sensitivity to the environment, which are key characteristics for applications in chemical sensing. Furthermore, 2DMs’ superior electrical and optical properties, combined with their excellent mechanical characteristics such as robustness and flexibility, make these materials ideal components for the fabrication of a new generation of high-performance chemical sensors. Depending on the specific device, 2DMs can be tailored to interact with various chemical species at the non-covalent level, making them powerful platforms for fabricating devices exhibiting a high sensitivity towards detection of various analytes including gases, ions and small biomolecules. Here, we will review the most enlightening recent advances in the field of chemical sensors based on atomically-thin 2DMs and we will discuss the opportunities and the challenges towards the realization of novel hybrid materials and sensing devices.

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Chemical sensing with 2D materials

Graphene oxide (GO) prepared by modified hummers method was used as adsorbent for removal of heavy metal ions. The oxygenous functional groups on the surface of GO were primarily responsible for the sorption of metal ions. The effects of the parameters of pH value, contact time, Cu(II) concentration, and adsorbent dosage on adsorption were examined. The sorption process conformed to the Freundlich isotherm, and the maximum sorption capacity of 117.5 mg g−1 was observed at an initial pH value of 5.3 after agitating for 150 min. It was also found that Cu-pretreated GO could be desorbed by HCl and the reusability of GO could still maintain above 90 % of its initial capability after ten cycles. The results suggest that GO is an effective adsorbent for copper ions removal in water treatment.

Highly Efficient Removal of Cu(II) from Aqueous Solution by Using Graphene Oxide

Multiwalled carbon nanotubes (MWCNTs) are split along the longitudinal direction to form quasi graphene oxide (QGO) by modified Hummers method and quasi graphene nanosheet/RuO2 (QGN/RuO2) composites with 40.0 wt% RuO2 loading are prepared by a one-step hydrothermal synthesis without any reducing agent. The characterization of morphology and structure shows that the amorphous RuO2 nanoparticles are uniformly dispersed on all the surfaces of QGN. The electrochemical measurements show that the QGN/RuO2 composites exhibit good capacitive properties compared to pure RuO2 and pure QGN in acidic, alkaline and even in neutral electrolytes. The specific capacitances of QGN/RuO2 in 1 M KOH, 1 M H2SO4, and 1 M Na2SO4 are 453.7, 415.7, 287.5 F g−1. Significantly, the QGN/RuO2 composites can achieve a high voltage window of 1.6 V and greatly increase the energy density (102.2 W h kg−1) and power density (1600 W kg−1) of supercapacitors in 1 M Na2SO4 (1 A g−1). These results demonstrate that the QGN/RuO2 composites are a promising material for high-performance supercapacitors.

Synthesis of RuO2 decorated quasi graphene nanosheets and their application in supercapacitors

Cross-linked chitosan(CS), cross-linked chitosan/graphene(CS/RGO10) and cross-linked chitosan/graphene oxide(CS/GO10) were prepared as adsorbents for Cu(II). The effects of pH, contact time, adsorbent dosage and initial concentration of Cu(II) on the adsorbing abilities of CS,CS/RGO10 and CS/GO10 to Cu(II) were investigated. The results demonstrate that the adsorption capacities of CS/GO10 and CS/RGO10 are greater than that of CS, especially at pH 5.0 and the adsorption capacities are 202.5, 150 and 137.5 mg/g, respectively. Their behaviors obey the Freundlich isotherm model very well. Additionally, CS/GO10 has the shortest time to achieve adsorption equilibrium among them and can be used as a perspective adsorbent for Cu(II).

http://www.zndxzk.com.cn/down/paperDown.aspx?id=2036874

Adsorption behavior of cross-linked chitosan modified by graphene oxide for Cu(II) removal

Polyaniline/tailored carbon nanotubes composite (PANI/TCN) synthesized via situ polymerization of aniline monomer in the presence of tailored carbon nanotubes (TCN) is reported as electrode material for supercapacitors. The morphology, structure, and thermostability of the composite were characterized by scanning electron microscope, Fourier transform infrared, and thermogravimetric analysis. The electrochemical property of the resulting material was systematically studied using cyclic voltammetry and galvanostatic charge–discharge. The results show that the short rod-like PANI dispersed well in the TCN with three-dimensional network structure. The as-prepared composite shows high specific capacitance and good cycling stability. A specific capacitance of 373.5 F g−1 at a current density of 0.5 A g−1 was achieved, which is much higher than that of pure PANI (324 F g−1). Meanwhile, the composite retains 61.7% capacity after 1000 cycles at a scan rate of 50 mV s−1. The enhanced specific capacitance and capacity retention indicates the potential of composite as a promising supercapacitor electrode material. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39971.

Enhanced performance by polyaniline/tailored carbon nanotubes composite as supercapacitor electrode material

Ag-Ru nanostructures were synthesized from a mixture of AgNO3 /R uCl 3 in ethylene glycol by solvothermal process without polyvinyl pyrrolidone. The characterization of morphology shows that the products were a mixture of nanorods and nanoparticles. The nanorods with an average diameter of 40 nm were the main structures of Ag-Ru products. The elemental analysis indicates that the products were composed of Ag and Ru. The electrochemical measurements show that Ag-Ru nanostructures exhibit higher catalytic activity than Ag for electroreduction of benzyl chloride.

Tingting Ye

Papers

Highly Efficient Removal of Cu(II) from Aqueous Solution by Using Graphene Oxide

Synthesis of RuO2 decorated quasi graphene nanosheets and their application in supercapacitors

Adsorption behavior of cross-linked chitosan modified by graphene oxide for Cu(II) removal

Enhanced performance by polyaniline/tailored carbon nanotubes composite as supercapacitor electrode material

Synthesis of Ag-Ru Nanostructures for Electroreduction of Benzyl Chloride