Polythiophene nanoparticles in aqueous media: ARTICLE

Interlayer Polymerization to Construct a Fully Conjugated Covalent Organic Framework as a Metal-Free Oxygen Reduction Reaction Catalyst for Anion Exchange Membrane Fuel Cells

Two-dimensional (2D) covalent organic frameworks (COFs) have a multilayer skeleton with a periodic π-conjugated molecular array, which can facilitate charge carrier transport within a COF layer. However, the lack of an effective charge carrier transmission pathway between 2D COF layers greatly limits their applications in electrocatalysis. Herein, by employing a side-chain polymerization strategy to form polythiophene along the nanochannels, a conjugated bridge is constructed between the COF layers. The as-synthesized fully conjugated COF (PTh-COF) exhibits high oxygen reduction reaction (ORR) activity with narrowed energy band gaps. Correspondingly, PTh-COF is tested as a metal-free cathode catalyst for anion exchange membrane fuel cells (AEMFCs) which showed a maximum power density of 176 mW cm-2 under a current density of 533 mA cm-2. The density functional theory (DFT) calculation reveals that interlayer conjugated polythiophene optimizes the electron cloud distribution, which therefore enhances the ORR performance. This work not only provides new insight into the construction of a fully conjugated covalent organic framework but also promotes the development of new metal-free ORR catalysts.

Promoting electrocatalytic carbon monoxide reduction to ethylene on copper-polypyrrole interface

The renewable energy-powered electroreduction of carbon dioxide or monoxide (CO) has been emerging as an attractive means to decarbonize the emission-intensive chemical manufacturing, which heavily relies on fossil fuels nowadays. One potential approach to promote the activity of electrocatalysts is to construct hybrid interface that can increase the stability of intermediates on electrode surfaces. Herein we developed a copper nanoparticle/polypyrrole (Cu-Ppy) nanowire composite as an efficient electrocatalyst for electrochemical CO reduction reaction. Compared to pure Cu nanoparticles, the Cu-Ppy composite exhibited a dramatically enhanced Faradaic efficiency of converting CO to ethylene (C₂H₄) from 34% to 69% at -0.78 V vs. reversible hydrogen electrode (RHE) in KOH electrolyte, and an excellent C₂H₄ partial current density of 276 mA·cm^-2 at -1.18 V vs. RHE. Density functional theory calculations showed that the Cu-Ppy composite could bind CO more strongly as compared to pure Cu. As the Ppy coating allowed to stabilize OCCO*, a key intermediate in the C₂H₄ formation, both the activity and selectivity of Cu-Ppy for CO-to-C₂H₄ were increased. Our work suggests that constructing rationally designed hybrid interface can tune the local environment of catalyst surface toward enhanced activity and product selectivity.

Synthesis and Properties of Thiophene and Aniline Copolymer Using Atmospheric Pressure Plasma Jets Copolymerization Technique

This paper investigates the properties of thiophene and aniline copolymer (TAC) films deposited by using atmospheric pressure plasma jets copolymerization technique relative to various blending ratios of aniline and thiophene monomer for synthesizing the donor–acceptor conjugated copolymers. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy are utilized to measure the surface morphology, roughness and film thickness of TAC films. Structural and chemical properties of TAC films are investigated by Fourier transforms-infrared spectroscopy (FT-IR), time of flight secondary ion mass spectrometry, and X-ray photoelectron spectroscopy. FE-SEM images show that the film thickness and nanoparticles size of the TAC films increase with an addition thiophene monomer in the aniline monomer. FE-SEM, FT-IR results show that TAC films are successfully synthesized on glass substrates in all cases. The iodine doped TAC film on the Si substrate with interdigitated electrodes shows the lowest electrical resistance at blending condition of thiophene of 25%.

Enzymatic Formation of Polyaniline, Polypyrrole, and Polythiophene Nanoparticles with Embedded Glucose Oxidase

Polyaniline (PANI), polypyrrole (Ppy), and polythiophene (PTh) composite nanoparticles with embedded glucose oxidase (GOx) were formed by enzymatic polymerization of corresponding monomers (aniline, pyrrole, and thiophene). The influence of monomers concentration, the pH of solution, and the ratio of enzyme/substrate on the formation of PANI/GOx, Ppy/GOx, and PTh/GOx composite nanoparticles were spectrophotometrically investigated. The highest formation rate of PANI-, Ppy-, and PTh-based nanoparticles with embedded GOx was observed in the sodium acetate buffer solution, pH 6.0. The increase of optical absorbance at λ_max = 440 nm, λ_max = 460 nm, and λ_max = 450 nm was exploited for the monitoring of PANI/GOx, Ppy/GOx and PTh/GOx formation, respectively. It was determined that the highest polymerization rate of PANI/GOx, Ppy/GOx, and PTh/GOx composite nanoparticles was achieved in solution containing 0.75 mg mL⁻¹ of GOx and 0.05 mol L⁻¹ of glucose. The influence of the enzymatic polymerization duration on the formation of PANI/GOx and Ppy/GOx composite nanoparticles was spectrophotometrically investigated. The most optimal duration for the enzymatic synthesis of PANI/GOx and Ppy/GOx composite nanoparticles was in the range of 48–96 h. It was determined that the diameter of formed PANI/GOx and Ppy/GOx composite nanoparticles depends on the duration of polymerization using dynamic light scattering technique (DLS), and it was in the range of 41–167 nm and 65–122 nm, when polymerization lasted from 16 to 120 h.