Dual-type electrochromic device based on polypyrrole and polythiophene derivatives

A dual-type electrochromic device was assembled using optically transparent electrodes modified with thin films of poly[(R)-(-)-3-(1-pyrrolyl)propyl-N-(3,5-dinitrobenzoyl)-α-phenylglycinate], poly(DNBP) and poly(3,4-ethylenedioxy-thiophene), PEDOT and a polymer electrolyte. After assembling, the device was characterized by spectroelectrochemical techniques. The best performance of this device could be obtained by adjusting the relative thickness of the active polymer films and the potential range of operation of the device. The device shows color variation during ca. 350 charge/discharge cycles and can be constructed under atmospheric conditions.     

Carbon doped with binary heteroatoms (N,X–C,where X = P,B, or S) derived from polypyrrole for enhanced electromagnetic wave absorption at microwave frequencies

Dual heteroatom-doped carbon materials show great promise as electromagnetic wave absorbers. However, synthesizing carbons containing multiple heteroatoms at controlled heteroatom doping levels has provided challenges to date. Herein, we report a simple method for manufacturing dual heteroatom doped carbons (N,X–C, where X = P, B, or S) by direct carbonization of polypyrrole synthesized in the presence of H₃PO₄, H₃BO₃, or H₂SO₄, respectively. The heteroatom content of the N,X–C products could be precisely tuned by varying amounts of acid dopant used in the polypyrrole synthesis. The N,X–C materials showed excellent electromagnetic wave absorption properties, especially N,S₁–C (prepared using equimolar amounts of pyrrole and H₂SO₄) which offered a wide absorption bandwidth up to 6.6 GHz (11.38–18 GHz), and a RL_min of ?32.3 dB (14.2 GHz) at 2.5 mm at a ?ller loading of 9.0 wt%. The outstanding electromagnetic wave absorption performance of N,S₁–C was attributed to the presence of N dopant species, defects, C–S, and C–SO_x groups, which optimized dipole polarization and conduction loss in the dielectric loss leading to excellent impedance matching.     

Response surface optimization and finite element homogenization study of the effective elastic modulus and electrical conductivity of MXene-polypyrrole hybrid nanocomposite as electrode material for electronic energy storage devices

Electrical energy storage devices are crucial for energy storage and distribution purposes. MXene (MX), a 2D material, and conductive organic polymers, such as polypyrrole (PPy), have been widely used as electrode material in electronic energy storage devices. This work calculated the elastic modulus and the electrical conductivity of a MX/PPy nanocomposite electrode using a finite element model. Response Surface Methodology (RSM) was used to optimize the electrical conductivity and elastic modulus response variables based on the finite element (FE) simulation findings. By assigning appropriate weights to these response factors in the optimization technique, the impacts of mass fraction and aspect ratio (AR) of MX inclusion on the electrical conductivity values and elastic modulus of the electrode were analyzed. When compared to the experimental findings, the results demonstrated that the suggested finite element model could provide a satisfactory estimate of the electrical conductivity and elastic modulus of the electrodes made of MX and PPy. However, these response variables might be optimized by using the response surface approach. Therefore, when RSM was employed, both electrical conductivity and Youngs modulus could be adjusted to close to their respective maximum optimal values, with a predicted electrical conductivity of 474.33 S/m and an elastic modulus of 3.24 GPa, at 50% mass fraction of the MX and the AR of 0.2. Based on these results, if a MX/PPy nanocomposite electrode could be built to achieve this modulus and electrical conductivity, such electrode would be a viable material for metal-ion batteries.     

Selective CO2 Electroreduction to Formate on Polypyrrole-Modified Oxygen Vacancy-Rich Bi2O3 Nanosheet Precatalysts by Local Microenvironment Modulation

Challenges remain in the development of highly efficient catalysts for selective electrochemical transformation of carbon dioxide (CO₂) to high-valued hydrocarbons. In this study, oxygen vacancy-rich Bi₂O₃ nanosheets coated with polypyrrole (Bi₂O₃@PPy NSs) are designed and synthesized, as precatalysts for selective electrocatalytic CO₂reduction to formate. Systematic material characterization demonstrated that Bi₂O₃@PPy precatalyst can evolve intoBi₂O₂CO₃@PPy nanosheets with rich oxygen vacancies (Bi₂O₂CO₃@PPy NSs) via electrolyte-mediated conversion and function as the real active catalyst for CO₂ reduction reaction electrocatalysis. Coating catalyst with a PPy shell can modulate the interfacial microenvironment of active sites, which work in coordination with rich oxygen vacancies in Bi₂O₂CO₃ and efficiently mediate directional selective CO₂ reduction toward formate formation. With the fine-tuning of interfacial microenvironment, the optimized Bi₂O₃@PPy-2 NSs derived Bi₂O₂CO₃@PPy-2 NSs exhibit a maximum Faradaic efficiency of 95.8% at −0.8 V (versus. reversible hydrogen electrode) for formate production. This work might shed some light on designing advanced catalysts toward selective electrocatalytic CO₂ reduction through local microenvironment engineering.     

Conductive Polymer-Coated 3D Printed Microneedles: Biocompatible Platforms for Minimally Invasive Biosensing Interfaces

Conductive polymeric microneedle (MN) arrays as biointerface materials show promise for the minimally invasive monitoring of analytes in biodevices and wearables. There is increasing interest in microneedles as electrodes for biosensing, but efforts have been limited to metallic substrates, which lack biological stability and are associated with high manufacturing costs and laborious fabrication methods, which create translational barriers. In this work, additive manufacturing, which provides the user with design flexibility and upscale manufacturing, is employed to fabricate acrylic-based microneedle devices. These microneedle devices are used as platforms to produce intrinsically-conductive, polymer-based surfaces based on polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). These entirely polymer-based solid microneedle arrays act as dry conductive electrodes while omitting the requirement of a metallic seed layer. Two distinct coating methods of 3D-printed solid microneedles, in situ polymerization and drop casting, enable conductive functionality. The microneedle arrays penetrate ex vivo porcine skin grafts without compromising conductivity or microneedle morphology and demonstrate coating durability over multiple penetration cycles. The non-cytotoxic nature of the conductive microneedles is evaluated using human fibroblast cells. The proposed fabrication strategy offers a compelling approach to manufacturing polymer-based conductive microneedle surfaces that can be further exploited as platforms for biosensing.     

Overoxidized poly(3,4-ethylenedioxythiophene)-overoxidized polypyrrole composite films with enhanced electrocatalytic ability for rutin and luteolin determination

In this study, a simple and effective method was proposed to improve the electrocatalytic ability of overoxidized poly(3,4-ethylenedioxythiophene)-overoxidized polypyrrole composite films modified on glassy carbon electrode for rutin and luteolin determination. The composite electrode was prepared by cyclic voltammetry copolymerization with LiClO₄-water as the supporting electrolyte. The peak current of rutin and luteolin on the composite electrode gradually decreased or even disappeared with the increase in the positive potential limit. After incubation in NaOH–ethanol solution with a volume ratio of 1:1, the composite electrodes prepared at positive potential limit greater than 1.5 V exhibited enhanced differential pulse voltammetry peak currents, reduced charge transfer resistance, larger effective specific surface area and higher electron transfer rate constant. The composite electrode prepared in the potential range of 0–1.7 V showed optimal electrocatalytic performance. The X-ray photoelectron spectroscopy results indicated that the content of –SO₂/–SO and –C=N– groups in the composite film increased significantly after incubation. Further, the Raman spectra and Fourier transform infrared spectra revealed that the thiophene ring structure changed from benzene-type to quinone-type, and the quinone-type pyrrole ring was formed. The electrocatalytic mechanism of the composite film was proposed based on the experimental results and further verified by Density Functional Theory calculation.     

DNA Programmable Peroxidase Activity of Oxidized Polypyrrole Quantum Dots

Significant progress has recently been made in the application of oxidized graphene (GO) quantum dots as enzyme mimics in various biomedical fields due to their bio-compatibility and excellent solubility in physiological media. However, their catalytic performance and controllability are barely satisfactory. Here, this study constructs oxygen-functionalized polypyrrole quantum dots (o-ppy QDs) with excellent peroxidase activity in a mild condition. Compared with oxidized graphene QDs, o-ppy QDs exhibit superior catalytic efficiency (120 times higher than HRP). More importantly, it is found that guanine (G) and adenine (A) bases possess higher binding affinities to o-ppy QDs. G base is able to significantly increase the peroxidase activity while A base decreases the activity, providing a fascinating method to precisely regulate the catalytic activity of o-ppy QDs in a programmable manner by the design of DNA sequences. The enhancement on the peroxidase by G base regulation is attributed to the existence of carbonyl group that promotes its catalytic activity, while A base tends to block the original carbonyl group on o-ppy QDs. Based on this feature, a colorimetric and fluorescent dual-mode biosensor for detecting DNA methylation is developed. This study holds significant theoretical and practical implications for the development of nanozymes and precise regulation of their catalytic activity.