Development of polymer–dopant interactions during electropolymerization, a key factor in determining the redox behaviour of conducting polymers

A universal strategy: Rational construction of noble metal nanoparticle-shell/conducting polymer nanofiber-core electrodes with enhanced electrochemical performances

To address a challenge for decoration of noble metal nanoparticles (NMNPs)-shell on conducting polymer nanofiber (CPNF) electrodes (i.e. NMNP-shell/CPNF-core electrodes) for boosting electrochemical performances, a two-step strategy comprising chemical pre-deposition and electrochemical deposition is designed. The strategy shows a high universality in terms of the diversity of NMNP-shell elements (single-element: AgNP-shell, AuNP-shell, PtNP-shell, PdNP-shell; multi-element: Au/Pt/PdNP-shell) and the independence of conductive substrates of electrodes. The shells are composed of high-density NMNPs and have strong adhesion to CPNF-cores. It is demonstrated that in response to a specific applied electrical stimulus, the resulting low doping level of CPNFs facilitates the generation of high-density nucleation sites (small NMNPs) by chemical pre-deposition (as high capability of electron transfer and low resistance to electron transfer from CP chains to NM ions), which is indispensable for the formation of NMNP-shells on CPNF-cores by electrochemical deposition. The decoration of NMNP-shells can significantly enhance the electrochemical performances of CPNF electrodes. Moreover, the great practicality and reliability of NMNP-shell/CPNF-core electrodes in use as an electrocatalytic platform are confirmed. This universal strategy opens up a new avenue to construct high-dimension shell/core-nanostructured electrodes.

Cation exchange behavior during the redox switching of poly (3,4-ethylenedioxythiophene) films

Poly (3,4-ethylenedioxythiophene), PEDOT, films were synthesized at room temperature by potentiodynamic and potentiostatic step deposition in aqueous solutions containing EDOT monomer and LiClO4. In some solutions, the effect of small amounts of sodium dodecylsulfate, SDS, on the polymerization rate of EDOT and on the stiffness of the obtained PEDOT film was studied. The obtained PEDOT films were transferred in aqueous solutions containing cations with different molar mass, such as H+, Li+, Na+, K+, and Cs+. The apparent molar masses of the exchanged species during potentiodynamic experiments were determined by in situ microgravimetry. These measurements underlined the importance of the electrolyte chosen for electropolymerization process. It is known that SDS anions can be trapped inside the polymer layer during electropolymerization, providing them with a cation exchange behavior. However, even if the PEDOT films were deposited from an electrolyte without SDS, they still acted as cation exchangers.

A Heavily Surface-Doped Polymer with the Bifunctional Catalytic Mechanism in Li-O2 Batteries

The application of conducting polymers (CPs) in energy storage systems is greatly limited by insufficient reversibility and stability. Here, we successfully incorporated functionalized dopants (Fe(CN)63- [FCN] and PO43- ions) in CPs matrixes to achieve a preferable electrochemical performance. A stable cation inserting/expulsing behavior of surface-doped polycarbazole (PCz) is demonstrated in our work, where doping levels and semiconductor properties of PCz are effectively controlled to adjust their redox properties and stability. With carbon nanotube (CNT) films as the substrate, the CNT/PCz:FCN composite is initially adopted as a free-standing catalytic electrode in Li-O2 cells. The molecule-level dispersed FCN dopants on the surface can work as bifunctional redox mediators on the charge-discharge process. Thus, this composite can not only achieve a low charge plateau of 3.62 V and a regular growth of capacities from 1,800 to 4,800 mAh/gCNT, but also maintain the most of charge voltages under 4.0 V for 150 cycles.

Conducting polymers in electrochemical sensing: factors influencing the electroanalytical signal

The paper highlights the intrinsic role of the conducting polymers (CPs) in CP-based electrochemical sensing devices. The effects of specific parameters of the electrochemical synthesis and overall measurement protocol, such as nature of the solvent and doping ions, the characteristics of the electrochemical polymerisation procedure, the nature of the CP-carrying substrates, and the composition of the medium used for the electroanalytical measurement, are discussed in an attempt to provide guidelines necessary for optimisation of CP-based electrochemical sensing. The lesser stability of CPs is also addressed as one of the main possible drawbacks of these materials in comparison to inorganic-based sensors.

Conducting polymer based electrochemical biosensors

Conducting polymer (CP)-based electrochemical biosensors have gained great attention as such biosensor platforms are easy and cost-effective to fabricate, and provide a direct electrical readout of the presence of biological analytes with high sensitivity and selectivity.