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Relevant academic research and scientific papers

Substituent effect on supercapacitive performances of conducting polymer-based redox electrodes: Poly(3′,4′-bis(alkyloxy) 2,2′:5′,2″-terthiophene) derivatives

This work reports the synthesis of novel poly(3′,4′-bis(alkyloxy)terthiophene) derivatives (PTTOBu, PTTOHex, and PTTOOct) and their supercapacitor applications as redox-active electrodes. The terthiophene-based conducting polymers have been derivatized with different alkyl pendant groups (butyl-, hexyl-, and octyl-) to explore the effect of alkyl chain length on the surface morphologies and pseudocapacitive properties. The electrochemical performance tests have revealed that the length of alkyl substituent created a remarkable impact over the surface morphologies and charge storage properties of polymer electrodes. PTTOBu, PTTOHex, and PTTOOct-based electrodes have reached up to specific capacitances of 94.3, 227.3, and 443 F?g?1 at 2.5 mA?cm?2 constant current density, respectively, in a three-electrode configuration. Besides, these redox-active electrodes have delivered satisfactory energy densities of 13.5, 29.3, and 60.7 W?h?kg?1 and power densities of 0.98, 1, and 1.1 kW?kg?1 with good capacitance retentions after 10,000 charge/discharge cycles in symmetric solid-state micro-supercapacitor devices.

Low Oxidation Potential Tetrathiafulvalene Analogues Based on 3,4-Dialkoxythiophene π-Conjugating Spacers

Tetrathiafulvalene analogues involving dihexyloxythiophene (1), ethylenedioxythiophene (2), and bis(3,4-dihexyloxy-2-thienyl)ethylene (3) as conjugating spacer and diversely substituted at the 1,3-dithiole ring (R) have been synthesized. Electronic absorption spectra show the expected decrease of HOMO-LUMO gap when increasing the electron-releasing power of R or the length of the conjugating spacer. Cyclic voltammetry (CV) shows that whereas compounds 1 and 2 are reversibly oxidized into their cation radical and dication through two one-electron steps, for compounds 3 the dication is formed directly via a two-electron transfer. Comparison of the data for compounds 2 and 3 with those of their respective analogues based on thiophene and dithienylethylene shows that introduction of the electron-donating alkoxy groups at the 3 and 4 positions of the thiophene ring produces a 150-200 mV negative shift of the first redox potential (E°1). On the other hand, CV data for compounds 1 and 2 reveal several unusual features such as E°1 ≈ 0.10 V/SCE ranking among the lowest known to date and a Coulombic repulsion between positive charges in the dication larger than for the analogue π-donors based on unsubstituted thiophene. These results are interpreted by a major reorganization of the electronic distribution in the donor molecule due to alkoxy groups: the highest electron density moving from the 1,3-dithiole moiety toward the central thiophene ring.