Electrochemical,Structural, and Thermogravimetric Studies of Activated Supercapacitor Electrodes Based on Carbonized Cellulose Cloth

Russian Journal of Physical Chemistry A - The high–temperature reagentless activation of carbonized cellulose cloth is used to manufacture supercapacitor (SC) electrodes with different fast...     

Effect of the functionalizing of carbon nanotubes on the electrodeposited catalysts’ structure and catalytic properties

The structure and hydrophilic-hydrophobic properties of functionalized single-wall carbon nanotubes are studied by the standard porosimetry method. It is shown that the functionalized nanotubes have highly hydrophilic surface; at that the summary surface area measured “by octane” decreased, as a result of the functionalizing, due to the blocking of the nanotubes’ inner channels by the functional groups located at the nanotubes’ ends. The nanotubes’ capacitive properties are studied; their charging-discharging curves appeared being highly reversible, unlike those of other carbonaceous materials. Catalytic properties of the functionalized nanotubes are studied, with particular tendency toward their using as a carrier of platinum catalysts for the methanol oxidation and oxygen electroreduction reactions. When minor amounts (5–10 μg cm⁻²) of platinum or platinum-ruthenium alloy are deposited onto the nanotubes’ hydrophilic surface, uniform layer of the catalyst is formed, with specific surface area up to 150–300 m² g⁻¹; high current of the methanol oxidation or oxygen electroreduction is observed at these catalysts. When the catalyst deposit mass increased, its specific surface area decreased, as well as the specific current of the reactions occurring thereon. When the current is related to the electrochemically active unit surface, the catalytic activity is nearly the same both for different catalyst mass deposited onto the nanotubes and the same catalyst mass at different carbonaceous carriers.     

Graphene-Based Aerogels Possessing Superhydrophilic and Superhydrophobic Properties and Their Application for Electroreduction of Molecular Oxygen

Colloid Journal - A composite aerogel with superhydrophobic external surface has been synthesized from reduced graphene oxide and polytetrafluoroethylene taken in a weight ratio of 1 : 1. The...     

Surface conductivity measurements for porous carbon electrodes

A method for measuring the surface conductivity in porous electrodes was developed. The knowledge of surface conductivity is very important for simulation and optimization of the capacitive deionization of aqueous solutions, which is a new promising and economical method for water desalination. The surface conductivity (SC) is the tangential (longitudinal) conductivity of a double electric layer (DEL). The SC involves the conductivity induced by the conductivity of the counterions of the surface groups in a highly disperse carbon electrode κ_sg and the surface conductivity κ_sch induced by the electrostatic charge of the inner surface of the electrode pores and the charge-compensating ions of the solution, i.e., the classical DEL. The value of κ_sg depends on the concentration of the surface groups C _sg on carbon, i.e., their exchange capacity, and κ_sch depends on the potential E. SC measurements were performed on activated porous carbon electrodes CH900 and SAIT. This SC measurement procedure is another method for studying DEL.     

A comparative analysis of graphene oxide films as proton conductors

The electrical conductivity of graphene oxide (GO) films in vapors of water and acid solutions is found to be close to the conductivity of a film formed after drying the solution of phenol-2,4-disulfonic acid in polyvinyl alcohol, which is known to be a proton conductor. We found that the conductivity of a GO film in vapors of the H₂O–H₂SO₄ electrolyte possesses a sharp maximum at ~1 % by weight of sulfuric acid. The highest conductivity of GO films can be expected when placing the films over acid vapors where the acid concentration is essentially lower than in the acid solutions at their maximum conductivity. Since the conductivity of the H₂O–H₂SO₄ electrolyte itself has a maximum at ~30 % by weight of sulfuric acid, the use of intermediate concentrations of H₂SO₄ is recommended in practical applications. The GO films permeated with water or acid solution in water are expected to possess the proton-exchange properties similar to those of other proton-exchanging membranes.     

Reduced graphene oxide as a protective layer of the current collector of a lithium-ion battery

The possibility of protecting the current collector of the cathode of a lithium-ion battery from the corrosive agents of electrolyte by creating a protective shell of reduced graphene oxide on the collector surface was studied. The positive effect was found to be a decrease in the degree of Faraday processes. The results of scanning electron microscopy, XRD analysis, Raman spectroscopy, and cyclic voltammetry were presented.