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1.
Appl Biochem Biotechnol ; 190(2): 423-436, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31376051

RESUMO

Lignocellulosic hydrolysate contains complex nonsugar compounds and undegraded sugars in the process of preparing platform compound levulinic acid (LA) and furfural by one-step dilute-acid hydrolysis. For efficiently and comprehensively utilizing the hydrolysate, a series of polar modified resins were synthesized for adsorption and separation of the sugarcane bagasse hydrolysate to obtain platform compounds and fermentable hydrolysate simultaneously. The adsorption capacities of LA and furfural were optimized to 85.32 mg/g and 33.55 mg/g on polar modified resin prepared with 80 wt% glycidyl methacrylate (GMA -80), which was much higher than nonpolar resin (4.16 mg/g and 16.14 mg/g). GMA-80 obtained the best comprehensive adsorption property, whose desorption rates were 99.90% and 89.86% for LA and furfural, respectively, and its regeneration performance was also excellent, indicating that the resin is a potential adsorbent and expected to be used in the separation and purification of the lignocellulosic hydrolysate.

2.
Phys Chem Chem Phys ; 19(36): 24689-24695, 2017 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-28861575

RESUMO

α-V2O5 nanowires with a layered structure have been fabricated through a two-step procedure. When measured as a pseudo-capacitive electrode with a three-electrode configuration in 1 M Na2SO4 aqueous solutions, α-V2O5 exhibits ideal capacitive characteristics with a specific capacitance of ∼238 F g-1 at a high current of 2 A g-1, but poor cycling stability with a continuous drop in the first 2000 cycles before it is maintained. To find possible solutions towards this problem, the energy storage behavior of the α-V2O5 electrode has been carefully investigated. In situ Raman analysis suggests that it is electrolytic hydrated cations [Na(H2O)n]+ rather than anions (SO42-) that are involved in the energy storage process through reversible adsorption/desorption on the surface or intercalation/deintercalation at the interlayer of the (001) planes accompanied by interlayer spacing expansion/contraction. Moreover, the electrochemical quartz crystal microbalance results indicate that, besides a reversible mass change, there is a continuous mass loss that may originate from slow dissolution of V2O5, which should bear the main responsibility for the poor stability (initial dramatic drop). Hence, how to inhibit dissolution, such as by coating or adding additives in the electrolyte, is found to be the key approach to improve the stability of V2O5 based electrodes.

3.
ACS Appl Mater Interfaces ; 9(15): 13173-13180, 2017 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-28353335

RESUMO

A facile and cost-efficient approach to functionalize raw carbon fiber paper (CFP) used for a self-standing capacitive electrode has been proposed here. Benefiting from the improved specific surface area and surface functional groups, the functionalized CFP (F-CFP) showed much enhanced capacitive performance, 3 orders of magnitude higher than that of the raw CFP. It delivered the areal capacitance of 1275 mF cm-2 at 5 mA cm-2 with a rather wide voltage window of 1.4 V (-0.4 to 1 V vs Ag/AgCl) in 0.5 M H2SO4. However, in a neutral 1 M Na2SO4 aqueous solution, although the areal capacitance of 1115 mF cm-2 at 3 mA cm-2 is slightly smaller, the potential window is much wider (2 V, -1 to 1 V vs Ag/AgCl), indicating a high overpotential of hydrogen evolution. The areal capacitance was still as high as 722 mF cm-2 at a very fast charge-discharge current density of 50 mA cm-2, and about 66% of the initial capacitance (at 3 mA cm-2) was remained in Na2SO4, indicating considerable rate capability.

4.
ACS Appl Mater Interfaces ; 8(36): 23721-8, 2016 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-27561652

RESUMO

Self-standing and flexible films worked as pseudocapacitor electrodes have been fabricated via a simple vacuum-filtration procedure to stack δ-MnO2@carbon nanotubes (CNTs) composite layer and pure CNT layer one by one with CNT layers ended. The lightweight CNTs layers served as both current collector and supporter, while the MnO2@CNTs composite layers with birnessite-type MnO2 worked as active layer and made the main contribution to the capacitance. At a low discharge current of 0.2 A g(-1), the layered films displayed a high areal capacitance of 0.293 F cm(-2) with a mass of 1.97 mg cm(-2) (specific capacitance of 149 F g(-1)) and thickness of only 16.5 µm, and hence an volumetric capacitance of about 177.5 F cm(-3). Moreover, the films also exhibited a good rate capability (only about 15% fading for the capacitance when the discharge current increased to 5 A g(-1) from 0.2 A g(-1)), outstanding cycling stability (about 90% of the initial capacitance was remained after 5,000 cycles) and high flexibility (almost no performance change when bended to different angles). In addition, the capacitance of the films increased proportionally with the stacked layers and the geometry area. E.g., when the stacked layers were three times many with a mass of 6.18 mg cm(-2), the areal capacitance of the films was increased to 0.764 F cm(-2) at 0.5 A g(-1), indicating a high electronic conductivity. It is not overstated to say that the flexible and lightweight layered films emerged high potential for future practical applications as supercapacitor electrodes.

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