Daize Mo

Poly(thieno[3,4- b ]-1,4-oxathiane): Medium Effect on Electropolymerization and Electrochromic Performance

The asymmetrical sulfur analog of 3,4-ethylenedioxythiophene (EDOT), thieno[3,4-b]-1,4-oxathiane (EOTT), was synthesized, and its electropolymerization was comparatively investigated by employing different solvent-electrolyte systems (room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6), CH2Cl2-Bu4NPF6, and CH2Cl2-BmimPF6). Further, the effect of solvents and supporting electrolytes on the structure, morphology, electrochemical, electronic, and optical properties and electrochromic performance of the obtained poly(thieno[3,4-b]-1,4-oxathiane) (PEOTT) films were minutely studied. PEOTT film with a band gap (Eg) of about 1.6 eV could be facilely electrodeposited in all the solvent-electrolytes and displayed excellent electroactivity, outstanding redox stability in a wide potential window, and improved thermal stability. Cyclic voltammetry showed that EOTT could be electropolymerized at a lower oxidation potential in BmimPF6 (∼1.0 V vs Ag/AgCl) due to several advantanges of RTIL BmimPF6 itself, such as high intrinsic conductivity and mild chemical conditions, etc., and the resulting PEOTT film exhibited compact morphology with better electroactivity and stability and higher electrical conductivity. On the other hand, PEOTT films from all the sovent-electrolytes also showed the electrochromic nature by color changing from gray blue to green, and further kinetic studies revealed that PEOTT had decent contrast ratios (36%), higher coloration efficiencies (212 cm(2)/C in BmimPF6), low switching voltages, moderate response time (1.2 s), excellent stability, and color persistence. From these results, PEOTT provides more plentiful electrochromic colors and holds promise for display applications.

Electrosynthesis and characterization of aminomethyl functionalized PEDOT with electrochromic property

We herein report the electrosynthesis of an aminomethyl functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) derivative, poly(2′-aminomethyl-3,4-ethylenedioxythiophene) (PEDOT-MeNH2), in CH2Cl2-Bu4NPF6 (0.1 mol·L-1) system containing 2% boron trifluoride diethyl etherate (BFEE). The electrochemical behavior, structure characterization, thermal properties and surface morphology of this novel polymer were systematically investigated by cyclic voltammetry (CV), Fourier-transform infrared spectroscopy (FTIR), thermogravimetry (TG) and scanning electron microscopy (SEM), respectively. Electrochemistry results demonstrated that PEDOT-MeNH2 film displayed good redox properties and high electrochemical stability. Besides, PEDOT-MeNH2 films exhibited the electrochromic nature with obvious color changing from purple in the reduced form to blue upon oxidation. By further investigation, kinetic studies revealed that PEDOT-MeNH2 film had decent contrast ratio (41.8%), favorable coloration efficiency (152.1 cm2·C-1), low switching voltages and moderate response time (2.4 s). Satisfactory results implied that the obtained PEDOT-MeNH2 film is a promising optoelectronic material and holds promise for electrochromic devices and display applications.

Electrosynthesis and electrochemical capacitive behavior of a new nitrogen PEDOT analogue-based polymer electrode

In this work, poly(N-methyl-3,4-dihydrothieno[3,4-b][1,4]oxazine) (PMDTO), a new nitrogen poly(3,4-ethylendioxythiophene) (PEDOT) analogue, was synthesized by an electrochemical deposition method, and the capacitive properties of PMDTO were investigated and compared with those of PEDOT. The structure and morphology of PMDTO were characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermal analysis. The pseudocapacitive properties of the as-prepared PMDTO electrodes have been examined by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) measurements and electrochemical impedance spectroscopy (EIS) in 0.1 mol L−1 CH3CN–Bu4NBF4 electrolyte solution. The as-prepared PMDTO electrode showed a high specific capacitance of 154.3 F g−1 at a discharge current density of 3 A g−1 and exhibited cycling stability with the maximal capacitance retention of nearly 71% after 500 cycles at a high current density of 10 A g−1. Additionally, the asymmetrical supercapacitor based on PMDTO and PEDOT electrodes exhibited a maximum specific capacitance of 63.5 F g−1 and an energy density of 12.7 W h kg−1 at a power density of 0.59 kW kg−1. These results implied that the PMDTO electrode can be used as a potential electrode material for supercapacitors.

One-step template-free electrodeposition of novel poly(indole-7-carboxylic acid) nanowires and their high capacitance properties

Poly(indole-7-carboxylic acid) (PICA) nanowires with conductivity of 5 × 10−2 S cm−1 were prepared by a facile, one-step and template-free electrodeposition method. The hydrogen bond interactions between the N–H group and the carboxyl group facilitated the formation of PICA nanowires. The diameter of the PICA nanowires was about 40 nm confirmed by scanning electron microscopy. Fourier transformation infrared spectroscopy and 1H NMR spectroscopy confirmed that the polymerization occurred at the C2 and C3 position on the indole ring. The electrochemical capacitance properties of the PICA nanowires were investigated with cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscope techniques. A remarkable specific capacitance of 373.2 F g−1 was obtained at a current density of 2.5 A g−1 in 1.0 M H2SO4 solution. PICA nanowires presented an excellent cycle life with 91% specific capacitance retention after 1000 charge–discharge processes. The energy density of the symmetric full cell based on two PICA electrodes was 7.03 W h kg−1 at a power density of 4500 W kg−1. These results implied that the PICA nanowires will be a promising electrode material for supercapacitors.

Synthesis and characterization of chiral PEDOT enantiomers bearing chiral moieties in side chains: chiral recognition and its mechanism using electrochemical sensing technology

In this work, we present a pair of chiral PEDOT derivatives named poly((R)-2-(chloromethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine) ((R)-PEDTC) and poly((S)-2-(chloromethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine) ((S)-PEDTC), which were employed as excellent chiral recognition materials for fabricating chiral sensors and then discriminating between 3,4-dihydroxyphenylalanine (DOPA) enantiomers. Importantly, the mechanism of the stereospecificity of the interaction between the DOPA enantiomers and chiral polymers was discussed specifically. A series of performances of corresponding polymers were characterized in some detail using different strategies including CV, CD, FT-IR, UV-vis, SEM, and TG. The CD spectrum indicated that (R)-PEDTC and (S)-PEDTC are mirror symmetric. CV shows that the polymers had superior redox reversibility in CH3CN–Bu4NPF6. Finally, different electrochemical methods including CV, square wave voltammetry (SWV) and differential pulse voltammetry (DPV) were introduced for the discrimination of DOPA enantiomers. Satisfactory measurement results demonstrated that (R)-PEDTC/GCE and (S)-PEDTC/GCE exhibited excellent enantioselectivity of DOPA enantiomers and the tendency was for anisotropic interaction between (R)-PEDTC and L-DOPA, and (S)-PEDTC and D-DOPA. This implied that the obtained polymer films could be promising candidates as enantioselective materials in the electrochemical sensor field.