Jan M. Skowroński

Electrochemical behavior of nickel deposited on reticulated vitreous carbon

Abstract The electrochemical performance of nickel deposited on reticulated vitreous carbon (RVC) has been investigated in solutions of KOH. For comparison, the study of sintered nickel and nickel deposited on gold wire behavior were also included. Our results indicate that the RVC covered with nickel is a good carrier for Ni(OH) 2 /NiOOH—an electrode material, used in rechargeable batteries. Ni/RVC saturated with Ni(OH) 2 shows behavior similar or even better than that of sintered Ni saturated with Ni(OH) 2 .

Passivation of zinc in alkaline solution effected by chromates and CrO3-graphite system

Electrochemical properties of porous zinc electrode in alkaline solution have been modified by the additive of chromium compounds such as chromates and CrO3–graphite system. Insertion of chromates inside the zinc electrode caused the limited solubility of the anodic dissolution products and their retention in the electrode interior. Different behaviour of the passivated zinc electrode was observed depending on cation of the used chromate. The improvement of cyclic performance of zinc has also been noted after the electrode is admixed with CrO3–graphite system containing intercalated/incorporated oxide. Electrochemical properties of zinc electrode strongly depend on the way of chromium insertion to active material of anode. Anodic and cathodic charges have been measured during potentiodynamic cycles for the observation of passivating effect.

Glass-like Carbon Spheres — Activation, Porosity and Application Possibilities

A brief review on spherical carbons, including fullerenes and related spherical particles, is first provided, followed by a review of the results on air activation, porosity and applications focused on glass-like carbon spheres derived from phenolic resin spheres. Kinetic studies of the oxidation in air provide a fundamental understanding of activation process of glass-like carbon spheres. On the basis of the results, a new activation procedure, viz. two-step activation, is proposed, which provides ca. 10% higher oxidation yield in obtaining a comparative pore structure. Some possibilities for applications of these glass-like carbon spheres are also described, such as the adsorption/desorption of CO2 gas and chlorinated methanes, the adsorption of organic molecules from their aqueous solutions, and the provision of electrodes for electric double layer capacitors and lithium ion rechargeable batteries.

ZnCl2-CrO3-H2SO4-Graphite Bi-Intercalation Compound: Synthesis, Structure and Electrochemical Transformation

Abstract The paper deals with the synthesis of ZnCl2-CrO3-H2SO4-graphite bi-intercalation compound (ZnCl2-CrO3-H2SO4-GBC). For observing the concentration profiles of intercalates in both ZnCl2-GIC and ZnCl2-CrO3-GBC the energy dispersive X-ray (EDX) analysis coupled with the scanning electron microscopy (SEM) were used. The X-ray diffraction (XRD) analysis and the cyclic voltammetric (CV) measurements were used to investigate the transformation of the starting ZnCl2-GIC to the ternary ZnCl2-CrO3-GIC followed by the successive electrochemical intercalation of H2SO4 resulting in the quaternary ZnCl2-CrO3-H2SO4-GBC. The present results argue for the formation of co-intercalation domains embedded in the lattice of bi-intercalation compound.

Synthesis and structure of FeCl3-CrO3-Graphite Bi-intercalation compound

Abstract The paper deals with the synthesis and structure of FeCl3-CrO3-graphite bi-intercalation compound (FeCl3-CrO3-GBC) prepared during the subsequent intercalation of chromium trioxide into stage-2 FeCl3-GIC/graphite system. From the results of the X-ray diffraction measurements and the scanning electron microscopy coupled with energy dispersive X-ray analysis it was concluded that the product consists of a mixture of saturated FeCl3-CrO3-GBC and stage-2 FeCl3-GIC. Based on the model of the transformation from stage-2 FeCl3-GIC/graphite system to FeCl3-CrO3-GBC, it can be understood that upon the subsequent intercalation process CrO3 is intercalated in the interlayer spacings of graphite both free and occupied by FeCl3. Due to the latter invasion the double-layer co-intercalation domain is formed whereas a part of FeCl3 is displaced to the zone of the pristine graphite present in the host FeCl3-GIC.

Photocatalytic Production of Hydrogen on Reduced CrO3-Graphite Intercalation Compound

Abstract A photocatalyst for the production of hydrogen due to UV-illumination of water was prepared by the reduction of CrO3-graphite intercalation compound (CrO3-GIC) in K-naphtalenide/anhydrous THF solution. The creation of active sites on the catalyst surface was estimated during the activity measurements performed in dynamic conditions. The EDX analysis revealed an exact coincidence of the distribution lines for chromium and potassium in the whole of graphite flakes of the CrO3-GIC/K photocatalyst.

Carbon Spheres as Possible Micro-Reinforcement of Cement-Based Composites

In this research, the influence of carbon spheres additive on mechanical properties of cement-carbon composites, such as flexural strength, flexural toughness and compression strength, were investigated. Carbon spheres were added to cement mortars in amount of 0.5 wt.%. Chemical treatment in hot nitric acid was applied in order to improve interfacial bonding between carbon fibres and cement mortar.

Synthesis, structure and electrochemical reactivity of CrO3-H2SO4- graphite bi-intercalation compounds prepared at room temperature

Abstract The paper deals with the synthesis, structure and electrochemical properties of CrO3-H2SO4-graphite bi-intercalation compound (CrO3-H2SO4-GBC) prepared at room temperature. In contrast to the two step process in which CrO3 is first intercalated chemically followed by electrochemical bi-intercalation of H2SO4, the method described in the paper allows the simultaneous intercalation of CrO3 and H2SO4 into graphite to give CrO3-H2SO4-GBC. The electrochemical method appeared to be suitable both to distinguish the original CrO3-H2SO4-GBCs of different structures and to enrich them with H2SO4 to provide stage-1 compound.

FTIR and thermal studies of FeCl3-CrO3-Graphite Bi-intercalation compound

Abstract FeCl3-CrO3-graphite bi-intercalation compound (FeCl3-CrO3-GBC) encompassing the double FeCl3-CrO3 co-intercalation layers was examined by FTIR spectroscopy and thermal analysis. The results obtained for FeCl3-CrO3-GBC were compared to those for the binary graphite intercalation compounds: FeCl3-GIC and CrO3-GIC. In FTIR spectrum for FeCl3-CrO3-GBC the bands observed in both FeCl3-GIC and CrO3-GIC were preserved with a slight shifting and new band around 1100–1200 cm−1 appeared. The reason for this feature is suggested to arise from the donor-acceptor interaction within FeCl3-CrO3-graphite system. Such an explanation is consistent with TG, DSC and XRD measurements.

Effect of Polyaniline on Electrochemical Intercalation of Sulphuric Acid into CrO3-Graphite Intercalation Compound

Abstract The influence of the oxidation reactions of aniline on the process of the subsequent intercalation of H2SO4 into CrO3-GIC is examined. It is shown that due to the polymerization of aniline the pristine CrO3-GIC is protected against deintercalation in 6 M H2SO4 and the anodic charge noted in the potential range of bi-intercalation increases significantly. From the results obtained it can be inferred that the products of polyaniline oxidation are involved in bi-intercalation reactions.