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The development of asymmetric supercapacitors (ASCs) with high power and energy density is greatly restricted by the low capacitance of the anode materials. V2O5 is a promising anode material with high theoretical capacity, but its low conductivity and high dissolution are not conducive to applications in energy storage. Herein, oxygen-vacancy PEDOT/V2O5 ultrathin nanosheets with a thickness of about 4.4 nm are fabricated by the oxidative polymerization of EDOT monomers on V2O5 nanosheets in the absence of other oxidants. The results of XPS and EPR confirm that the polymerization of PEDOT increases the oxygen vacancy concentration of V2O5. The PEDOT/V2O5 nanosheets exhibit a specific capacitance of 406 F g−1 at 2 mV s−1 and excellent cyclic stability in the mixed organic electrolyte of dimethyl carbonate and ethylene carbonate. The energy density of ASCs composed of PEDOT/V2O5 as the anode and activated carbon as the cathode reaches 65 W h kg−1 at a power density of 1490 W kg−1. This means that PEDOT/V2O5 has enormous potential in high-energy storage. [ABSTRACT FROM AUTHOR]

Nanostructured conducting polymers (NCPs) have been extensively studied and widely applied in state-of-the-art technologies over the past few decades because they simultaneously offer the photoelectric features and processing advantages of polymeric conductors and the nano-size effect of nanomaterials. With rational design and synthesis, NCPs with controllable morphologies and physicochemical properties can exhibit fascinating electrical, optical, mechanical, and biological properties. In this review, we describe in detail the synthetic methodology and the relationship of morphology–property of NCPs as well as their recent advances in biotherapy, biosensing, microwave absorbers for electromagnetic shielding, and various energy storage/conversion/saving devices. And last, since this field contains many immense scopes for exploration and development, we bring new insights along with a brief summary. [ABSTRACT FROM AUTHOR]

Conjugated fluorophores have been extensively used for fluorescence sensing of various substances in the field of life processes and environmental science, due to their noninvasiveness, sensitivity, simplicity and rapidity. Most existing conjugated fluorophores exhibit excellent light-emitting performance in dilute solutions, but their properties substantially decrease or even completely vanish due to severe aggregation quenching in the solid state. Herein, we synthesize a series of triazolopyridine–thiophene donor–acceptor–donor (D–A–D) type conjugated molecules with high absolute fluorescence quantum yields (ΦF) ranging from 80% to 89% in solution. These molecules also show unusual light-emitting properties in the solid state with ΦF of up to 26%. We find that owing to the protonation–deprotonation process of the pyridine ring, these compounds display obvious changes in both fluorescence wavelength and intensity upon addition of acids, and these changes can be readily recovered by the successive introduction of bases. By harnessing this phenomenon, we further show that these fluorophores can be employed for efficient and reversible fluorescence sensing of hydrogen ions in a broad pH range (0.0–7.0). With the fabrication of pH testing papers and ink-printed complex patterns including butterflies and letters on substrates, we demonstrate the application of such sensors to fluorescence indication or solid state pH detection for real samples such as volatile acidic/basic gas and water-quality analysis. [ABSTRACT FROM AUTHOR]

Bioelectronic interfacing with the human body including electrical stimulation and recording of neural activities is the basis of the rapidly growing field of neural science and engineering, diagnostics, therapy, and wearable and implantable devices. Owing to intrinsic dissimilarities between soft, wet, and living biological tissues and rigid, dry, and synthetic electronic systems, the development of more compatible, effective, and stable interfaces between these two different realms has been one of the most daunting challenges in science and technology. Recently, hydrogels have emerged as a promising material candidate for the next-generation bioelectronic interfaces, due to their similarities to biological tissues and versatility in electrical, mechanical, and biofunctional engineering. In this review, we discuss (i) the fundamental mechanisms of tissue–electrode interactions, (ii) hydrogels’ unique advantages in bioelectrical interfacing with the human body, (iii) the recent progress in hydrogel developments for bioelectronics, and (iv) rational guidelines for the design of future hydrogel bioelectronics. Advances in hydrogel bioelectronics will usher unprecedented opportunities toward ever-close integration of biology and electronics, potentially blurring the boundary between humans and machines. [ABSTRACT FROM AUTHOR]

Respiration is one of the most vital physiological activities of the human body. Abnormalities in the respiratory rates and patterns can ascertain the condition of the human body, such as sleeping, exercising, anaerobic threshold during athletic activity, etc. However, current respiratory sensor materials are often complicated in system and cumbersome in technology. This paper proposes a simple model breathing sensor preparation scheme that only requires electrodes to be attached to common insulating materials used in daily life. The basic working principle is: (a) conductive layer formation (the conductivity of hydrogen bonding induced water layer is mainly due to the proton transition), (b) signal acquisition and (c) health-status-feedback. The effects of the chemical and physical properties of different insulating materials on the respiratory detection caused by surface water condensation were studied for the first time. The different response mechanisms of several types of materials were studied in detail, and the selection criteria for sensing materials were given, which has great reference value for further research and industrial production. Considering the requirements of comfort, long-term hygiene (antibacterial) and excellent performance, etc., a complete human respiratory monitoring system specifically based on nitrile rubber films (NRFs) as wearable respiration sensors is constructed. This sensor achieved a good balance of several parameters. The signal changes by 3 orders of magnitude in cycles of inhalation and exhalation maximally. This universal patterning design scheme for respiratory sensors will be a significant reference for application and industrialization, and will have a profound impact on further fundamental research. [ABSTRACT FROM AUTHOR]

Owing to their excellent fluorescence properties and molecular wire signal amplification effect, water-soluble conjugated oligo-/polymer-based fluorescent sensors have been used for the detection of various metal ions, some of which have already been used in real applications in aqueous environments and biological systems. Herein, we synthesize water-soluble oligo(1-pyrenesulfonic acid) by one-step electropolymerization in boron trifluoride diethyl etherate (BFEE). This oligomer is demonstrated to be an excellent blue light-emitter with a high fluorescence quantum yield of approximately 0.68 in deionized water. We further find that oligo(1-pyrenesulfonic acid) can be employed to effectively detect Fe3+ in aqueous solution due to the aggregation fluorescence quenching of its oligomer chains. Minute sensing analytical results indicate that the oligomer displays good selectivity and a low detection limit (1.00 × 10−7 M), which are better than those of its monomer 1-pyrenesulfonic acid. Moreover, the fluorescence quenching of the oligomer can be recovered by introducing phosphates with outstanding reversibility (97% of its original intensity). With these results, electrosynthesized oligo(1-pyrenesulfonic acid) will be a good candidate for the determination of Fe3+ in aqueous solution. [ABSTRACT FROM AUTHOR]

Conjugated polymers containing selenophene have received attention due to their unique properties and promising application in organic electronics. Herein, to further improve the optoelectronic properties, two typical selenophenes containing [1,2,5]thiadiazolo[3,4-c]pyridine (PT)/[1,2,5]selenadiazolo[3,4-c]pyridine (PS) were synthesized by a donor–acceptor strategy and electropolymerized to form the donor–acceptor–donor polymers. The two precursors exhibited yellow and red emission characteristics with high quantum yields (∼0.48); the value was far greater than those for previously reported selenophenes. Furthermore, electrochromic studies demonstrated that the obtained polymers have superior coloration efficiencies (168 cm−2 C−1) than thiophene based analogues and fast response times (1.6 s). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A new nitrogen analog of 3,4-ethylenedioxythiophene (EDOT), N-methyl-3,4-dihydrothieno[3,4-b][1,4]oxazine (MDTO), was electropolymerized in different solvents (deionized water, acetonitrile, and propylene carbonate) using LiClO4 as the electrolyte. The structure and performance of as-prepared PMDTO polymers were systematically studied by cyclic voltammetry, UV-vis spectroscopy, FT-IR, SEM, thermogravimetry, spectroelectrochemistry and electrochromic techniques. To our surprise, solvents had a major influence on the electropolymerization of MDTO and properties of the resultant polymers, including morphology, electrochemistry, electronic and optical properties, and electrochromics, etc. In aqueous solution, MDTO revealed the lowest onset oxidation potential (0.19 V) than in acetonitrile (0.48 V) and propylene carbonate (0.49 V). However, PMDTO films showed rather poor cycling stability in water, while outstanding stability in acetonitrile and propylene carbonate. Films prepared in propylene carbonate displayed a rather smooth morphology, lower band gap (1.65 eV), higher transparency (97.3%) and a contrast ratio (44.6%) at λ = 466 nm. PMDTO films obtained in acetonitrile showed significantly higher coloration efficiency (169.5 cm2 C−1) than in other two solvents (∼97.6 cm2 C−1) with a moderate contrast ratio (24.5%). [ABSTRACT FROM AUTHOR]

Two novel EDOT end-capped monomers, namely, 2,8-di-2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl-dibenzothiophene (DBT-EDOT), and 2,8-di-2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl-dibenzofuran (DBF-EDOT), were synthesised via Stille coupling and electropolymerised to form conjugated polymers P(DBT-EDOT) and P(DBF-EDOT). The monomers exhibited blue-light-emitting characteristics, and DFT calculations revealed band gap values of 4.20 eV for DBT-EDOT and 4.34 eV for DBF-EDOT, while those of the corresponding polymers were brought down to 2.46 eV for P(DBT-EDOT) and 2.58 eV for P(DBF-EDOT), respectively. Moreover, both of the polymers displayed good electrochromic properties with colour switching between yellow in the reduced state and purple in the oxidised state. Structure characterisation and properties of monomers and as-formed polymers using FTIR spectroscopy, UV-vis spectroscopy, surface morphology, fluorescence spectroscopy, electrochemistry, and spectroelectrochemistry, together with structure–property relationships, were systematically investigated and comprehensively discussed. [ABSTRACT FROM AUTHOR]

Owing to their excellent fluorescence properties and molecular wire signal amplification effect, water-soluble conjugated oligo-/polymer-based fluorescent sensors have been used for the detection of various metal ions, some of which have already been used in real applications in aqueous environments and biological systems. Herein, we synthesize water-soluble oligo(1-pyrenesulfonic acid) by one-step electropolymerization in boron trifluoride diethyl etherate (BFEE). This oligomer is demonstrated to be an excellent blue light-emitter with a high fluorescence quantum yield of approximately 0.68 in deionized water. We further find that oligo(1-pyrenesulfonic acid) can be employed to effectively detect Fe3+ in aqueous solution due to the aggregation fluorescence quenching of its oligomer chains. Minute sensing analytical results indicate that the oligomer displays good selectivity and a low detection limit (1.00 × 10−7 M), which are better than those of its monomer 1-pyrenesulfonic acid. Moreover, the fluorescence quenching of the oligomer can be recovered by introducing phosphates with outstanding reversibility (97% of its original intensity). With these results, electrosynthesized oligo(1-pyrenesulfonic acid) will be a good candidate for the determination of Fe3+ in aqueous solution. [ABSTRACT FROM AUTHOR]