Feitian Ran

Nitrogen-doped porous carbon derived from biomass waste for high-performance supercapacitor.

High capacitance property and low cost are the pivotal requirements for practical application of supercapacitor. In this paper, a low cost and high capacitance property nitrogen-doped porous carbon with high specific capacitance is prepared. The as-prepared nitrogen-doped porous carbon employing potato waste residue (PWR) as the carbon source, zinc chloride (ZnCl2) as the activating agent and melamine as nitrogen doping agent. The morphology and structure of the carbon materials are studied by scanning electron microscopy (SEM), N2 adsorption/desorption, X-ray diffraction (XRD) and Raman spectra. The surface area of the nitrogen-doped carbon which prepared under 700°C is found to be 1052m(2)/g, and the specific capacitance as high as 255Fg(-1) in 2M KOH electrolyte is obtained utilize the carbon as electrode materials. The electrode materials also show excellent cyclability with 93.7% coulombic efficiency at 5Ag(-1) current density of for 5000cycles.

A facile and rapid preparation of highly crumpled nitrogen-doped graphene-like nanosheets for high-performance supercapacitors

Highly crumpled nitrogen-doped graphene-like nanosheets (CN-GLSs) with a high specific surface area (1169 m2 g−1) and large pore volume (2.58 cm3 g−1) are prepared from a macroporous resin via simultaneous urea gasification expansion and CaCl2 activation methods. The CN-GLSs are tested as electrodes for supercapacitors and present excellent electrochemical performance.

Nitrogen-doped porous carbon obtained via one-step carbonizing biowaste soybean curd residue for supercapacitor applications

In this work, we present a facile approach to prepare nitrogen-doped porous carbon materials via one-step carbonizing biowaste soybean curd residue (SCR) as the biomass carbon precursor. The morphology, structure and textural properties of the carbon materials are investigated by field emission scanning electron microscopy, transmission electron microscopy, N2 sorption isotherms, and X-ray photoelectron spectroscopy, respectively. The SCR carbonized at 700 °C exhibits a high charge storage capacity with a specific capacitance of 215 F g−1 at a current density of 0.5 A g−1 and good stability over 5000 cycles. Moreover, the assembled symmetric supercapacitor device possesses a energy density of 9.95 W h kg−1 at a power density of 236 W kg−1, which is higher than that of commercially available supercapacitors. The high supercapacitor performance of the porous carbon can be due to the high surface area and effective nitrogen-doping, indicating it has great potential for supercapacitors.

Eco-friendly superabsorbent composite based on sodium alginate and organo-loess with high swelling properties

A novel superabsorbent composite with high swelling properties was synthesized by the grafted co-polymerization of partially neutralized acrylic acid (AA) onto a sodium alginate (NaAlg) backbone in the presence of organo-loess. The FTIR spectra, XRD patterns and SEM micrographs prove that the AA monomers were grafted onto the NaAlg backbone, and the organo-loess dispersed into the polymer matrix that improved the porous structure, which was verified by element mapping. TGA and DSC results indicate that the incorporation of loess enhances the thermal stability of the superabsorbent. Swelling results confirm that proper amount of organo-loess in the superabsorbent can enhance the swelling capability and salt-resistant performance. The maximum equilibrium water absorbency of the superabsorbent composite incorporated with 10 wt% organo-loess in distilled water and 0.9 wt% NaCl aqueous solution were 656 g g−1 and 69 g g−1, respectively. Furthermore, the superabsorbent composite exhibited good buffer ability to external pH in the range from 4 to 10 and water retention ability. According to the performance of the eco-friendly superabsorbent composite, it can be used as a promising candidate for applications in various fields.

High energy density of quasi-solid-state supercapacitor based on redox-mediated gel polymer electrolyte

A novel redox-mediated gel polymer (PVA–H2SO4–ARS) is prepared by introducing alizarin red S (ARS) into a polyvinyl alcohol–sulphuric acid (PVA–H2SO4) gel polymer system, and a symmetric supercapacitor using the gel polymer as electrolyte and activated carbon as electrode is also assembled. The PVA–H2SO4–ARS gel polymer has excellent bending, compressing and stretching mechanical properties. The introduction of ARS increases the ionic conductivity of the gel polymer, and improves the pseudocapacitance of the supercapacitor. As expected, the PVA–H2SO4–ARS gel polymer electrolyte has a high conductivity of 33.3 mS cm−1, and the supercapacitor with PVA–H2SO4–ARS electrolyte exhibits a larger electrode specific capacitance (441 F g−1) than the one with PVA–H2SO4 electrolyte (160 F g−1) at the same current density of 0.5 A g−1. Simultaneously, the supercapacitor with PVA–H2SO4–ARS electrolyte exhibits high energy density (39.4 W h kg−1) and good charge–discharge stability. Therefore, this novel electrolyte has good prospects for improving the electrochemical performance of an energy storage device.

White clover based nitrogen-doped porous carbon for a high energy density supercapacitor electrode

We have employed the biomaterial white clover as a carbon precursor and ZnCl2 as an activating agent to prepare white clover carbons (WCCs). The WCC-2 (mass ratios of white clover and ZnCl2 is 1 : 2) possesses as high as 6.9 wt% nitrogen content and 857 m2 g−1 BET surface area. Furthermore, it exhibits 233.1 F g−1 specific capacitance at a current density of 1.0 A g−1, even 82.9% capacitance retention at 20 A g−1 in 2 mol L−1 KOH electrolyte. The specific capacitance could remain at almost about 100.0% when the cycle number is between the 200–5000 cycles. Because of the wide potential window (0–2.0 V) and high specific capacitance, the WCC-2//WCC-2 symmetric capacitor shows an energy density of 30–13.1 W h kg−1 under the power outputs of 503.5–9991.5 W kg−1 in 0.5 mol L−1 Na2SO4 electrolyte. The results demonstrate WCC-2 can be a promising candidate for the electrode material of high performance supercapacitors.

Effectiveness of an Eco-friendly Polymer Composite Sand-Fixing Agent on Sand Fixation

A novel and eco-friendly xanthan gum-g-poly(acrylic acid)/laterite (XG-g-PAA/laterite) organic-inorganic composite polymer used as chemical sand-fixing agent (CSFA) was successfully prepared by grafted copolymerization of natural XG, partially neutralized acrylic acid (NaA), and laterite in solution. FTIR spectra confirmed that NaA had been grafted onto XG chains, and the –OH groups of laterite participated in polymerization reaction. The influence of the content of CSFA on sand-fixing effect was investigated, and the results of the aging test indicated that the CSFA had remarkable water resistance, heat resistance, anti-freeze-thaw, and anti-ultraviolet aging performances, which could meet the requirement of application in the harsh desert environment. Moreover, it also showed excellent water-retaining and anti-evaporation properties.

Superior performance of an active electrolyte enhanced supercapacitor based on a toughened porous network gel polymer

A primary challenge of gel electrolytes in the development of flexible and wearable devices is their weak mechanical strength and poor electrochemical performances. Here, we prepare a novel PVA (polyvinyl alcohol)–H2SO4–BAAS (bromamine acid sodium) gel polymer with a porous network structure as both electrolyte and separator, which achieves excellent mechanical strength, maintains a high ionic conductivity of 21.4 mS cm−1 and provides a reversible redox reaction for enhanced supercapacitor performance. Surprisingly, the operating voltage of the present active electrolyte enhanced supercapacitor (AEESC) is up to 1.5 V, which is much larger than that of the previously reported active electrolyte based supercapacitors (about 1.0 V). Furthermore, the AEESC exhibits a maximum specific capacitance of 390 F g−1 at a current density of 0.8 A g−1, a remarkably high energy density of 30.5 W h kg−1 at a power density of 600 W kg−1 and good cycling stability. Additionally, such a device displays only a small capacitance loss when the gel polymer is under a large tensile strain of 100% or under a high pressure of 2000 kPa. Meanwhile, the capacitance of the device was maintained very well after 500 complete bending cycles, indicating that the robust gel polymer endows the fabricated AEESC with good flexibility and electrochemical stability.

Preparation and properties of an organic–inorganic composite superabsorbent based on attapulgite

A novel, low-cost, and eco-friendly organic–inorganic composite superabsorbent is successfully prepared in aqueous solution by graft copolymerization of partially neutralized acrylic acid (AA), polyvinyl alcohol (PVA), and attapulgite (APT) using ammonium persulfate (APS) as an initiator and N,N-methylenebisacrylamide (MBA) as a crosslinker. The structure and morphology of the composite superabsorbent are characterized by means of Fourier transform infrared, X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy. The effects of APT content which can affect the water absorbency and the pH, ionic surfactants and different saline solution which can affect swelling capabilities of the composite superabsorbent are also investigated. The results show the composite superabsorbent give the best absorption up to 680 g/g and 53 g/g in distilled water and 0.9 wt% NaCl solution, high water absorbency over a wide pH range of 4–10, high swelling capacity in anionic surfactant than that of cationic solution, which makes it promising for potential applications in modern agriculture and horticulture. On the other hand, the composite superabsorbent can be used for removing multivalent metal ions.

Preparation and Sand-Fixing Property of a Novel and Eco-friendly Organic-Inorganic Composite

A novel guar gum/poly(acrylic acid)/loess (GG-g-PAA/loess) organic-inorganic composite used as chemical sand-fixing agent (CSFA) is successfully prepared in aqueous solution by polymerization guar gum (GG), neutralized acrylic acid (AA) and loess. The correlations between the content of prepared composite and the sand-fixing properties are investigated. The results show that the CSFA can significantly improve the compressive strength of the sand fixation specimens. Meanwhile, the sand fixation specimens have good thermal, freeze-thaw and UV-radiation aging stabilities to withstand the changes in temperature and strong UV radiation. Besides, the specimens treated with sand-fixing agent shows excellent water retention capacity. GRAPHICAL ABSTRACT