[Show abstract][Hide abstract] ABSTRACT: Electrode materials with a three-dimensional (3D) network structure and high-conductivity are crucial for the development of robust high-performance supercapacitors. Herein, a facile method has developed for the covalent intercalation of graphene oxide (GO) with bacterial cellulose (BC) fibers via one-step esterification to construct a 3D cross-linked structural scalffords. The as-prepared composite exhibits a tensile strength of 18.48 MPa and an elongation at break of 24%. With an outstanding electrical conductivity of 171 S m-1, the composite electrode demonstrates a good mass-specific capacitance of 160 F g-1 at 0.4 A g-1 current density. Robust supercapacitor is demonstrated with an outstanding capacitance retention of 90.3% over 2000 recycles. The impressive mechanical and electrochemical properties of covalently intercalated BC/GO composite may open new avenue in developing cross-linked GO nanocomposites for stretchable electronics. This is the first report on the preparation of covalent intercalating BC/GO composite for robust supercapacitor application.
[Show abstract][Hide abstract] ABSTRACT: A two-dimensional (2D) low bandgap polymer (PDTS-Ph-TTz) based on dithieno[3,2-b:2’,3’-d]silole (DTS) with phenyl substitution on bridging silicon atom and thiazolo[5,4-d]thiazole (TTz) was designed and synthesized for photovoltaic application. The impact of conjugated side chains on the optical, electrochemical and energy levels of the polymer was studied. The phenyl substituted DTS polymer exhibited 0.16 eV downs-shifted highest occupied molecular orbital (HOMO) energy level and ca. 0.1 eV narrowed bandgap in comparison to the corresponding polymers with alkyl substitution on silicon bridge. The influence of blend weight ratio, PFN layer, mixed solvent, THF exposure and polar solvent treatment and thermal annealing on the performance of PDTS-Ph-TTz:PC71BM devices was studied. PDTS-Ph-TTz:PC71BM (1:1, weight ratio) devices delivered the highest power conversion efficiency of 2.14% by using PFN layer and THF annealing. Thermal annealing was found to exert negative effect on the device performance. The morphology evolution of blend films processed with different solvents explained the difference in device performance. The results indicate the phenyl substitution is an effective way to tune the HOMO and bandgap of polymer donors for enhanced photovoltaic performance with the as-demonstrated 2D-conjugated DTS structure.
Physical Chemistry Chemical Physics 10/2014; · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Novel AC regioisomer cationic cyclodextrins have been successfully prepared with azide/alkylne click chemistry CDs. The clicked CDs were explored for the enantioseparation of acidic racemates in capillary electrophoresis.
[Show abstract][Hide abstract] ABSTRACT: The nanocomposite (denoted as GR-AuNPs-CD-CS) of graphene (GR), gold nanoparticles (AuNPs), chitosan (CS) and β-cyclodextrin (β-CD) was prepared to modify a glassy carbon electrode. The as-modified electrode was explored for the ultrasensitive detection of dopamine (DA) and uric acid (UA). The modified electrode demonstrated linearly increased current response in the concentration range of 0.1–120 µm for DA and 0.05–70 µm for UA, with so far the best detection limit for DA and UA. Good stability and repeatability were further demonstrated for the as-made sensor.
[Show abstract][Hide abstract] ABSTRACT: A general methodology has been proposed for the straightforward access to 4,8-functionalized benzo[1,2-b:4,5-b′]dithiophenes (BDTs) via Pd mediated coupling reactions including Suzuki–Sonogashira coupling and carbon–sulfur bond formation reactions. This versatile platform can be used to construct a library of BDT core centred conjugated systems, featuring large fused-ring structure and good charge mobility, where a hole mobility of 0.061 cm2 V−1 s−1 is demonstrated. With the energy level fine-tuned with functionalization, the charge transporting BDTs show great potential for donor–acceptor polymers.
[Show abstract][Hide abstract] ABSTRACT: A method is reported for the preparation of novel electrode by layer-by-layer assembly of haemoglobin (Hb), gold (Au) nanoparticles, chitosan (CS) and graphene (GR) onto glassy carbon electrode (GCE). The Au/GR–CS substrate shows an obvious promotion for the direct electron transfer between Hb and GCE. The surface concentration (Г*) of Hb on the as-modified electrode can be as high as 4.33 × 10−9 mol/cm2, which is 228 times higher than the theoretical value for Hb monolayer on bare GCE. The Au/GR–CS/GCE shows good electrocatalytic performance for the reduction of hydrogen peroxide within a linear range from 2 to 935 μM, a low detection limit of 0.35 μM (S/N = 3) and high sensitivity of 347.1 mA cm−2 M−1. The Au/GR–CS nanocomposite demonstrates as a versatile matrix for immobilizing redox protein to realize direct electrochemistry and hence prepare efficient and robust biosensor.
Sensors and Actuators B Chemical 07/2014; 197:164–171. · 3.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Eight single-isomer ammonium-β-cyclodextrin derivatives with different side chains were successfully developed as chiral selectors for the chiral separation of selected racemates in capillary electrophoresis. The number of substituted groups at N-atom as well as the alkyl chain length greatly influenced the chiral separation. With the numbers of hydroxylalkyl groups at N-atom growing, the aqueous solubility of resolving agents were distinctly decreased and chiral separation ability was also significantly reduced. The apparent complex stability constants between CDs and analytes were further determined. The best enantioseparations of hydroxyl acids was achieved with the use of mono-6A-(3-hydroxypropyl)-1-ammonium-β-cyclodextrin chloride and mono-6A-(3-methoxypropyl)-1-ammonium-β-cyclodextrin chloride. The nuclear magnetic resonance experiments were carried out using them with mandelic acid as guest molecules, revealing the inclusion pattern as well as electrostatic interactions and hydrogen bonding interactions as additional chiral driving force. The contribution of potential interaction sites in the sidearm could enhance the enantioseparations.This article is protected by copyright. All rights reserved
[Show abstract][Hide abstract] ABSTRACT: New ternary composites of MnO2 nanorods, polyaniline (PANI) and graphene oxide (GO) have been prepared by a two-step process. The 100 nm-long MnO2 nanorods with a diameter ~20 nm are conformably coated with PANI layers and fastened between GO layers. The MnO2 nanorods incorporated ternary composites electrode exhibits significantly increased specific capacitance than PANI/GO binary composite in supercapacitors. The ternary composite with 70% MnO2 exhibits a highest specific capacitance reaching 512 F/g and outstanding cycling performance, with ~97% capacitance retained over 5000 cycles. The ternary composite approach offers an effective solution to enhance the device performance of metal-oxide based supercapacitors for long cycling applications.
[Show abstract][Hide abstract] ABSTRACT: Novel monosubstituted dually cationic cyclodextrins (CDs) have been synthesized by anchoring different alkyl chain spaced imidazolium and ammonium sidearm onto the CD primary ring. These cationic CDs exhibit satisfactory enantioselectivities for amino acids and acidic racemates in aqueous capillary electrophoresis.
[Show abstract][Hide abstract] ABSTRACT: A novel cationic cyclodextrin, mono-6(A)-(3-methoxypropan-1-ammonium)-6(A)-β-cyclodextrin chloride, has been developed and used as chiral selector in capillary electrophoresis (CE). This chiral selector has three recognition sites: β-CD, ammonium cation and methoxy group in the sidearm to contribute three corresponding driving forces including inclusion complexation, electrostatic interaction and hydrogen bonding. This elegantly designed CD exhibits outstanding enantioselectivities in CE for a wide range of acidic and ampholytic racemates due to the extra hydrogen bonding for the chiral recognition. Under optimum pH 6.0, chiral resolutions over 10 can be readily achieved for acidic racemates with CD concentration below 10 mM. This cationic CD exhibits great potential for versatile chiral separation in CE. The finding in this study may be applied to construct new host-guest systems for practical applications.
Journal of Chromatography A 03/2012; 1246:98-102. · 4.61 Impact Factor