The influence of electrodeposited PPy film morphology on the electrochemical characteristics of Nafion-based energy storage devices

Pushing the Electrochemical Performance Limits of Polypyrrole Toward Stable Microelectronic Devices

Conducting polymers have achieved remarkable attentions owing to their exclusive characteristics, for instance, electrical conductivity, high ionic conductivity, visual transparency, and mechanical tractability. Surface and nanostructure engineering of conjugated conducting polymers offers an exceptional pathway to facilitate their implementation in a variety of scientific claims, comprising energy storage and production devices, flexible and wearable optoelectronic devices. A two-step tactic to assemble high-performance polypyrrole (PPy)-based microsupercapacitor (MSC) is utilized by transforming the current collectors to suppress structural pulverization and increase the adhesion of PPy, and then electrochemical co-deposition of PPy-CNT nanostructures on rGO@Au current collectors is performed. The resulting fine patterned MSC conveyed a high areal capacitance of 65.9 mF cm-2 (at a current density of 0.1 mA cm-2), an exceptional cycling performance of retaining 79% capacitance after 10,000 charge/discharge cycles at 5 mA cm-2. Benefiting from the intermediate graphene, current collector free PPy-CNT@rGO flexible MSC is produced by a facile transfer method on a flexible substrate, which delivered an areal capacitance of 70.25 mF cm-2 at 0.1 mA cm-2 and retained 46% of the initial capacitance at a current density of 1.0 mA cm-2. The flexible MSC is utilized as a skin compatible capacitive micro-strain sensor with excellent electromechanochemical characteristics.

Biorecognition of hydrogen peroxide using a novel electrochemical platform designed with Glossoscolex paulistus giant hemoglobin

The giant extracellular hemoglobin of the annelid Glossoscolex paulistus (HbGp; 3.6 MDa) is a valuable and underexplored supramolecular hemoprotein system for the biorecognition of reactive oxygen species. In this work, an efficient and simple electrochemical platform was designed for analyzing H₂O₂, using HbGp covalently immobilized on Nafion®-modified glassy carbon electrode, named as HbGp/Nafion/GCE. Voltammetric and spectroscopic studies revealed the importance of prior modification of the electrodic support with the conducting polymer to obtain satisfactory hemoglobin electroactivity, as well as a biocompatible microenvironment for its immobilization. In terms of biological activity, it was observed a greater reactivity of the biomolecule in acidic medium, enabling the detection of the analyte by a quasi-reversible mechanism, whose kinetics was limited by analyte diffusion. In the presence of H₂O₂, the native structure of hemoglobin (oxy-HbGp (Fe²⁺)) oxidizes to ferryl-HbGp (Fe⁴⁺) and this redox reaction can be monitored on HbGp/Nafion/GCE with a detection limit of 8.5 × 10^‒7  mol L^-1. In addition to high sensitivity, the electrochemical biosensor also provided reproducible, consistent, and accurate measurements. The electroanalytical method showed an appropriate performance to quantify different levels of H₂O₂ in milk samples, proving the potential of HbGp/Nafion/GCE for this purpose.