Ferrocene functionalized multi-walled carbon nanotubes as supercapacitor electrodes

Interleaved Electroactive Molecules into LDH Working on Both Electrodes of an Aqueous Battery-Type Device

By selecting two electroactive species immobilized in a layered double hydroxide backbone (LDH) host, one able to act as a positive electrode material and the other as a negative one, it was possible to match their capacity to design an innovative energy storage device. Each electrode material is based on electroactive species, riboflavin phosphate (RF) on one side and ferrocene carboxylate (FCm) on the other, both interleaved into a layered double hydroxide (LDH) host structure to avoid any possible molecule migration and instability. The intercalation of the electroactive guest molecules is demonstrated by X-ray diffraction with the observation of an interlayer LDH spacing of about 2 nm in each case. When successfully hosted into LDH interlayer space, the electrochemical behavior of each hybrid assembly was scrutinized separately in aqueous electrolyte to characterize the redox reaction occurring upon cycling and found to be a rapid faradic type. Both electrode materials were placed face to face to achieve a new aqueous battery (16C rate) that provides a first cycle-capacity of about 7 mAh per gram of working electrode material LDH/FCm at 10 mV/s over a voltage window of 2.2 V in 1M sodium acetate, thus validating the hybrid LDH host approach on both electrode materials even if the cyclability of the assembly has not yet been met.

Thermal and thermo-oxidative stability of a series of palladium and platinum ferrocenylamine sulfides and selenides

Ferrocenylamine complexes have found increasing applications in the fields of catalysis in various organic reactions, industry, medical treatments and enzyme–activity determinations. Therefore, information related to the thermal and thermo-oxidative stability of these compounds is important for such applications; however, this information is currently limited. Twenty previously prepared palladium and platinum ferrocenylamine complexes with systematic structural variations are examined for their thermal (under nitrogen) and thermo-oxidation stability (under atmospheric air) using thermogravimetry (TG), differential thermal analysis (DTG), and differential scanning calorimetry (DSC) techniques. Degradation products are identified by comparing thermogravimetric analysis and theoretical calculations. Structure–stability studies are also discussed. The results show that all the compounds have high thermal and thermo-oxidative stabilities of up to 265 and 173 °C, respectively. Electron–donating substituents enhance the thermal and thermo-oxidative stabilities of the palladium complexes ( t-Bu, selenide electrophiles and dielectrophiles), while those with destabilizing effects are aromatic substituents (Ph and tolyl). Most platinum ferrocenylamine sulfides and selenides show higher thermal and thermo-oxidative stabilities than their corresponding palladium analogs. All the prepared compounds show high thermal and thermo-oxidative stability which reinforces their catalytic and industrial applications. However, their thermal stability is higher than their thermo-oxidative stability.

ε-Polylysine-Based Macromolecules with Catalase-Like Activity to Accelerate Wound Healing by Clearing Bacteria and Attenuating Inflammatory Response

Wound healing has remained a critical challenge due to its susceptibility to bacterial infection and the unique biological inflammatory response. Safe and effective therapeutics are still lacking. Biodegradable macromolecules (ε-polylysine-g-ferrocene, EPL-g-Fc) were developed to accelerate wound healing by combating bacterial infection and attenuating inflammatory responses. The biodegradable macromolecules were prepared via a Schiff-based reaction between ferrocene carboxaldehyde (Fc) and ε-polylysine (EPL). Through the synergistic combination of positive-charged EPL and π-π stacked Fc, the macromolecules possess excellent antibacterial activities. EPL-g-Fc with catalase-like activity could modulate the oxidative microenvironment in mammalian cells and zebrafish by catalyzing H₂O₂ into H₂O and O₂. EPL-g-Fc could alleviate inflammatory response in vitro. Furthermore, the macromolecules could accelerate bacteria-infected wound healing in vivo. This work provides a versatile strategy for repairing bacteria-infected wounds by eliminating bacteria, modulating oxidative microenvironment, and alleviating inflammatory response.

Covalent grafting diazotized black phosphorus with ferrocene oligomer towards smoke suppression and toxicity reduction

In comparison with the thermal hazard of polymers, noxious smoke and gas produced by the combustion of polymers make the environment self-purification a huge challenge. As a new type of a highly effective flame retardant, black phosphorus (BP) can effectively decrease the thermal hazard of polymers, but its performances in smoke suppression and toxicity reduction are unsatisfactory. In this article, a method of covalently grafting diazotized BP with a ferrocene oligomer was applied to promote the smoke suppression and toxicity reduction efficiency of BP. In our work, the BP-NH nanomaterials with a mass of amino groups on the surface were acquired by diazotizing the BP. Then, the BP-Fe was obtained by covalently grafting the ferrocene chloride salt and nitrogen-containing heterocycles on the surface of BP. The smoke production rate (SPR) and total smoke production (TSP) values of the epoxy resin (EP) decreased by 49.8% and 52.5% with the addition of 2 wt% BP-Fe, respectively. In comparison with previous studies, this work was far more effective than the previous work in smoke suppression and flame retardant. The release of toxic gases (CO and HCN) and volatile organic compounds in the EP was also effectively inhibited at the same time. In addition, the storage modulus and tensile strength of nanocomposites increased by 35.1% and 27.2% with the addition of 1 wt% BP-Fe. This work also provides a new idea on how to simultaneously strengthen the toxic smoke suppression, mechanical properties, and flame retardant of polymer materials.

Taguchi L25 (54) Approach for Methylene Blue Removal by Polyethylene Terephthalate Nanofiber-Multi-Walled Carbon Nanotube Composite

A membrane composed of polyethylene terephthalate nanofiber and multi-walled carbon nanotubes (PET NF-MWCNTs) composite is used to adsorb methylene blue (MB) dye from an aqueous solution. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction techniques are employed to study the surface properties of the adsorbent. Several parameters affecting dye adsorption (pH, MB dye initial concentration, PET NF-MWCNTs dose, and contact time) are optimized for optimal removal efficiency (R, %) by using the Taguchi L25 (54) Orthogonal Array approach. According to the ANOVA results, pH has the highest contributing percentage at 71.01%, suggesting it has the most significant impact on removal efficiency. The adsorbent dose is the second most affected (12.08%), followed by the MB dye initial concentration of 5.91%, and the least affected is the contact time (1.81%). In addition, experimental findings confirm that the Langmuir isotherm is well-fitted, suggesting a monolayer capping of MB dye on the PET-NF-MWCNT surface with a maximum adsorption capacity of 7.047 mg g−1. Also, the kinetic results are well-suited to the pseudo-second-order model. There is a good agreement between the calculated (qe) and experimental values for the pseudo-second-order kinetic model.

An electrochemical amplification strategy based on the ferrocene functionalized cuprous oxide superparticles for the detection of NSE

A sandwich-type electrochemical immunosensor was designed utilizing ferrocene-functionalized cuprous oxide superparticles (Au/Fc@Cu_xO SPs) as the signal label and graphene supported by hollow carbon balls (HCNs-GR) as the substrate. The Cu_xO SPs possess a superparticle structure with synergistic properties of isotropy and promising catalytic activity. Ferrocene (Fc) was deposited on the Cu_xO SPs to act as the electronic transmission medium. The Au/Fc@Cu_xO SPs played a pivotal role in improving the sensitivity of the immunosensor. The graphene supported by hollow carbon balls (HCNs-GR) was used to modify the electrode surface. The embedding of hollow carbon nanospheres (HCNs) reduced the decrease of the effective surface area caused by the stacking of graphene nanotubes. Meanwhile, the load of carbon balls further increases the surface area of graphene, enabled HCNs-GR to immobilize antibodies more effectively, improved the sensitivity of the immunosensor. The proposed immunosensor showed a linear range from 500 fg/mL to 100 ng/mL, with the detection limit to 25.7 fg/mL.

1,5-anhydroglucitol biosensor based on light-addressable potentiometric sensor with RGO-CS-Fc/Au NPs nanohybrids

In this paper, a novel silicon-based light-addressable potentiometric sensor (LAPS) has been designed for the detection of 1,5-anhydroglucitol (1,5-AG) in human serum. Reduced graphene oxide-chitosan-ferrocene (RGO-CS-Fc)/AuNPs nanohybrids and pyranose oxidase (PROD) enzyme is used to fabricate biological sensitive membrane unit by layer-by-layer assembly technology. When a bias voltage is provided to the LAPS system, the catalytic oxidation reaction between 1,5-AG and PROD to produce H₂O₂. The by-product H₂O₂ can oxidize Fc(Fe²⁺) ions in RGO-CS-Fc nanohybrids into Fc(Fe³⁺) ions, which cause the potential of the sensitive membrane surface to change and the potential shift of I-V curve will generate a corresponding offset response. Under the optimal conditions, the potential shift of the LAPS is linearly related to the concentration of 1,5-AG at 10 µg·mL^-1 -350 µg·mL^-1 with the correlation coefficient of 0.97414. The sensitivity is 0.44273 mV/µg·mL^-1 and the lowest detection limit is 10 µg·mL^-1. In addition, the biosensor showed good specificity, acceptable stability and satisfactory recovery rates (91.28%-107.66%), which would be a potential testing methods in actual clinical samples.

4-Pentenoyl-isoleucyl-chitosan oligosaccharide and acrylamide functional monomer-dependent hybrid bilayer molecularly imprinted membrane for sensitive electrochemical sensing of bisphenol A

In this work, an electrochemical sensor was designed for trace monitoring of bisphenol A (BPA) by decorating a hybrid bilayer molecularly imprinted membrane (MIM) on a multi-walled carbon nanotube-modified glassy carbon electrode. When BPA in the MIM was eluted, a composite molecularly imprinted electrochemical sensor was constructed. Under optimal conditions, the developed sensor showed two linear relationships between ΔI p and BPA concentration in the range of 0.04 μM to 8 μM, as well as good selectivity and stability, and was also applied to detect BPA in water samples with desirable recoveries ranging from 92.0% to 107.0%.