Thermoactivated Electrical Conductivity in Perylene Diimide Nanofiber Materials

Thermoactivated electrical conductivity has been studied on nanofibers fabricated from the derivatives of perylene tetracarboxylic diimide (PTCDI) both in the dark and under visible light illumination. The activation energy obtained for the nanofibers fabricated from donor–acceptor (D–A) PTCDIs are higher than that for symmetric <i>n</i>-dodecyl substituted PTCDI. Such difference originates from the strong dependence of thermoactivated charge hopping on material disorder, which herein is dominated by the D–A charge-transfer and dipole–dipole interactions between stacked molecules. When the nanofibers were heated above the first phase transition temperature (around 85 °C), the activation energy was significantly increased because of the thermally enhanced polaronic effect. Moreover, charge carrier density can be increased in the D–A nanofibers under visible light illumination. Consistent with the theoretical models in the literature, the increased charge carrier density did cause decrease in the activation energy due to the up-shifting of Fermi level closer to the conduction band edge

Donor–Acceptor Supramolecular Organic Nanofibers as Visible-Light Photoelectrocatalysts for Hydrogen Production

Perylene tetracarboxylic diimide (PTCDI) derivatives have been extensively studied for one-dimensional (1D) self-assembled systems and for applications in photocatalysis. Herein, we constructed a PTCDI-based donor–acceptor (D–A) supramolecular system via in situ self-assembly on an indium tin oxide conductive glass surface. The self-assembled PTCDI nanostructures exhibit well-defined nanofibril morphologies and strong photocurrents. Interestingly, a strong and reversible electrochromic color change was observed during cyclic voltammetry. The color of the nanofibers changed from red to blue and then to violet as the reduction progressed to the radical anion and then to the dianion. This series of one-electron reductions was confirmed by UV absorption, electron paramagnetic resonance spectroscopy, and hydrazine reduction. Most importantly, these PTCDI nanofibers exhibit efficient photoelectrocatalytic hydrogen production with remarkable stability under xenon lamp illumination (λ ≥ 420 nm). Among the three nanofibers prepared, the fibers assembled from PTCDI molecule <b>2</b> were found to be the most effective catalyst with 30% Faradaic efficiency. In addition, the nanofibers produced hydrogen at a steady-state for more than 8 h and produced repeatable results in 3 consecutive testing cycles, giving them great potential for practical industrial applications. Under an applied bias voltage, the 1D intermolecular stacking along the long axis of the nanofibers affords efficient separation and migration of photogenerated charge carriers, which play a crucial role in the photoelectrocatalytic process. As a proof-of-concept, the D–A-structured PTCDI nanofibers presented herein may guide future research on photoelectrocatalysis based on self-assembled supramolecular systems by providing more options for material design of the catalysts to achieve greater efficiencies

Donor–Acceptor Supramolecular Organic Nanofibers as Visible-Light Photoelectrocatalysts for Hydrogen Production

Perylene tetracarboxylic diimide (PTCDI) derivatives have been extensively studied for one-dimensional (1D) self-assembled systems and for applications in photocatalysis. Herein, we constructed a PTCDI-based donor–acceptor (D–A) supramolecular system via in situ self-assembly on an indium tin oxide conductive glass surface. The self-assembled PTCDI nanostructures exhibit well-defined nanofibril morphologies and strong photocurrents. Interestingly, a strong and reversible electrochromic color change was observed during cyclic voltammetry. The color of the nanofibers changed from red to blue and then to violet as the reduction progressed to the radical anion and then to the dianion. This series of one-electron reductions was confirmed by UV absorption, electron paramagnetic resonance spectroscopy, and hydrazine reduction. Most importantly, these PTCDI nanofibers exhibit efficient photoelectrocatalytic hydrogen production with remarkable stability under xenon lamp illumination (λ ≥ 420 nm). Among the three nanofibers prepared, the fibers assembled from PTCDI molecule <b>2</b> were found to be the most effective catalyst with 30% Faradaic efficiency. In addition, the nanofibers produced hydrogen at a steady-state for more than 8 h and produced repeatable results in 3 consecutive testing cycles, giving them great potential for practical industrial applications. Under an applied bias voltage, the 1D intermolecular stacking along the long axis of the nanofibers affords efficient separation and migration of photogenerated charge carriers, which play a crucial role in the photoelectrocatalytic process. As a proof-of-concept, the D–A-structured PTCDI nanofibers presented herein may guide future research on photoelectrocatalysis based on self-assembled supramolecular systems by providing more options for material design of the catalysts to achieve greater efficiencies

Donor–Acceptor Supramolecular Organic Nanofibers as Visible-Light Photoelectrocatalysts for Hydrogen Production

Perylene tetracarboxylic diimide (PTCDI) derivatives have been extensively studied for one-dimensional (1D) self-assembled systems and for applications in photocatalysis. Herein, we constructed a PTCDI-based donor–acceptor (D–A) supramolecular system via in situ self-assembly on an indium tin oxide conductive glass surface. The self-assembled PTCDI nanostructures exhibit well-defined nanofibril morphologies and strong photocurrents. Interestingly, a strong and reversible electrochromic color change was observed during cyclic voltammetry. The color of the nanofibers changed from red to blue and then to violet as the reduction progressed to the radical anion and then to the dianion. This series of one-electron reductions was confirmed by UV absorption, electron paramagnetic resonance spectroscopy, and hydrazine reduction. Most importantly, these PTCDI nanofibers exhibit efficient photoelectrocatalytic hydrogen production with remarkable stability under xenon lamp illumination (λ ≥ 420 nm). Among the three nanofibers prepared, the fibers assembled from PTCDI molecule <b>2</b> were found to be the most effective catalyst with 30% Faradaic efficiency. In addition, the nanofibers produced hydrogen at a steady-state for more than 8 h and produced repeatable results in 3 consecutive testing cycles, giving them great potential for practical industrial applications. Under an applied bias voltage, the 1D intermolecular stacking along the long axis of the nanofibers affords efficient separation and migration of photogenerated charge carriers, which play a crucial role in the photoelectrocatalytic process. As a proof-of-concept, the D–A-structured PTCDI nanofibers presented herein may guide future research on photoelectrocatalysis based on self-assembled supramolecular systems by providing more options for material design of the catalysts to achieve greater efficiencies

Donor–Acceptor Supramolecular Organic Nanofibers as Visible-Light Photoelectrocatalysts for Hydrogen Production

Perylene tetracarboxylic diimide (PTCDI) derivatives have been extensively studied for one-dimensional (1D) self-assembled systems and for applications in photocatalysis. Herein, we constructed a PTCDI-based donor–acceptor (D–A) supramolecular system via in situ self-assembly on an indium tin oxide conductive glass surface. The self-assembled PTCDI nanostructures exhibit well-defined nanofibril morphologies and strong photocurrents. Interestingly, a strong and reversible electrochromic color change was observed during cyclic voltammetry. The color of the nanofibers changed from red to blue and then to violet as the reduction progressed to the radical anion and then to the dianion. This series of one-electron reductions was confirmed by UV absorption, electron paramagnetic resonance spectroscopy, and hydrazine reduction. Most importantly, these PTCDI nanofibers exhibit efficient photoelectrocatalytic hydrogen production with remarkable stability under xenon lamp illumination (λ ≥ 420 nm). Among the three nanofibers prepared, the fibers assembled from PTCDI molecule <b>2</b> were found to be the most effective catalyst with 30% Faradaic efficiency. In addition, the nanofibers produced hydrogen at a steady-state for more than 8 h and produced repeatable results in 3 consecutive testing cycles, giving them great potential for practical industrial applications. Under an applied bias voltage, the 1D intermolecular stacking along the long axis of the nanofibers affords efficient separation and migration of photogenerated charge carriers, which play a crucial role in the photoelectrocatalytic process. As a proof-of-concept, the D–A-structured PTCDI nanofibers presented herein may guide future research on photoelectrocatalysis based on self-assembled supramolecular systems by providing more options for material design of the catalysts to achieve greater efficiencies

Chemical Self-Doping of Organic Nanoribbons for High Conductivity and Potential Application as Chemiresistive Sensor

Intrinsically low electrical conductivity of organic semiconductors hinders their further development into practical electronic devices. Herein, we report on an efficient chemical self-doping to increase the conductivity through one-dimensional stacking arrangement of electron donor–acceptor (D–A) molecules. The D–A molecule employed was a 1-methylpiperidine-substituted perylene tetracarboxylic diimide (MP-PTCDI), of which the methylpiperidine moiety is a strong electron donor, and can form a charge transfer complex with PTCDI (acting as the acceptor), generating anionic radical of PTCDI as evidenced in molecular solutions. Upon self-assembling into nanoribbons through columnar π–π stacking, the intermolecular charge transfer interaction between methylpiperidine and PTCDI would be enhanced, and the electrons generated are delocalized along the π–π stacking of PTCDIs, leading to enhancement in conductivity. The conductive fiber materials thus produced can potentially be used as chemiresistive sensor for vapor detection of electron deficient chemicals such as hydrogen peroxide, taking advantage of the large surface area of nanofibers. As a major component of improvised explosives, hydrogen peroxide remains a critical signature chemical for public safety screening and monitoring