AC-Bipolar Electropolymerization of 3,4-Ethylenedioxythiophene in Ionic Liquids

Experimental Methods for Measuring Potential and Current Density Distributions at Bipolar Electrodes

Bipolar electrodes (BPEs) are wireless electrodes where electrochemical reactions occur without the need of ohmic contact but rather through an induced electric field established within the electrolytic solution. Although the contactless nature of these electrodes is one of the most captivating features in view of their numerous applications, at the same time, it also represents a limitation because potential and current density distributions cannot be exactly measured. Nevertheless, several experimental methods to indirectly detect these parameters on BPEs have been reported over the years, and they will be extensively described in this tutorial article.

Ultrasensitive Flexible NO2 Sensors with Remote-Controllable ADC-Electropolymerized Conducting Polymers on Plastic

Alternating- and direct-current (ADC) bipolar electropolymerization (EP) offers an efficient and scalable approach for the lateral synthesis of conjugated macromolecules, enabling the simultaneous polymerization and deposition of large conducting polymer films with intriguing fractal-like ramified topographies onto arbitrary insulating substrates under remote control. In this study, we presented the remote synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT):anion sensing films on a plastic substrate, aimed at their use in flexible nitrogen dioxide (NO2) gas sensors. Notably, the PEDOT:ClO3 films exhibited excellent gas-sensing characteristics, with a sensitivity of 54.8% to 50 ppm of NO2, minimal cross-sensitivity to other gases, and a detection limit of 0.726 parts per billion (ppb) for NO2. The sensing mechanism of the ADC-bipolar electropolymerized PEDOT:anion films was examined using spectroscopic analysis, microstructural characterization, and interaction energy computations. The findings revealed that the enhanced sensitivity of the PEDOT:ClO3 film was attributable to an appropriate electrostatic interaction between the counteranion (ClO3-) and NO2 molecules at the molecular scale, as well as the large surface area of the film resulting from hierarchical macrostructures. This study showed the practical application of the ADC-bipolar EP method for flexible organic gas sensors.

Electrochemical Formation of Ionic Porous Organic Polymers Based on Viologen for Electrochromic Applications

The systematic study of two ionic porous organic polymers (iPOPs) based on viologens and their first applications in the electrochromic field are reported. The viologen-based iPOPs are synthesized by electrochemical polymerization with cyano groups, providing a simple and controllable method for iPOPs that solves the film preparation problems common to viologens. After the characterization of these iPOPs, a detailed study of their electrochromic properties is conducted. The iPOP films based on viologens structure exhibit excellent electrochromic properties. In addition, the resulting iPOP films show high sensitivity to electrolyte ions of different sizes in the redox process. Electrochemical and electrochromic data of the iPOPs explain this phenomenon in detail. These results demonstrate that iPOPs of this type are ideal candidates as electrochromic materials due to their inherent porous structures and ion-rich properties.

A triple read-out visible biosensing platform based on multifunctional nanozyme and bipolar electrode for multi-mode detection and imaging of CEA

In this paper, a proposal of closed bipolar electrode (BPE) and nanozyme based multi-mode biosensing platform is first presented. As a novel integrated chip, multi-mode-BPE (MMBPE) combines enzyme-linked immunoassay (ELISA), electrochemiluminescence (ECL), ECL imaging and light emitting diode (LED) imaging, enabling highly sensitive triple read-out visible detection of cancer embryonic antigen (CEA). The ECL probe Ab2@Au@Co3O4/CoFe2O4 hollow nanocubes (HNCs) with excellent peroxidase (POD) activity is introduced into the BPE cathode through immune adsorption. The Au@Co3O4/CoFe2O4 HNCs can increase the rate of hydrogen peroxide oxidation of TMB, thus promoting the reaction, and can be used for ELISA detection of CEA at different concentrations. The modification of the BPE sensing interface and reporting interface involved the introduction of the luminescent reagent Ru(bpy)32+ to the BPE anode. The decomposition rate of H2O2 increased under the catalytic action of Au@Co3O4/CoFe2O4 HNCs nanozyme, leading to an accelerated electron transfer rate in the MMBPE system and an enhanced ECL signal from Ru(bpy)32+. The LED imaging technology further provides a convenient and visible approach for CEA imaging in which no additional chemicals are needed. The integration of nanoenzymes as the catalytic core in MMBPE system provides impetus, while the combination of nanozymes with BPE expands the application of nanoenzymes in the field of biological analysis. The integration of intelligent chips with multiple modes of detection shows portable, miniaturized, and integrated excellent properties which meets the requirements of modern detection devices and thus offers a flexible approach for determination of nucleic acids, proteins, and cells.