Alina Pruna

Supercapacitance of Single-Walled Carbon Nanotubes-Polypyrrole Composites

The composites based on carbon nanotubes (CNTs) and conducting polymers (CPs) are promising materials for supercapacitor devices due to their unique nanostructure that combines the large pseudocapacitance of the CPs with the fast charging/discharging double-layer capacitance and excellent mechanical properties of the CNTs. Here, we report a new electrochemical method to obtain polypyrrole (PPY)/single-walled carbon nanotube (SWCNT) composites. In the first step, the SWCNTs are covalently functionalized with monomeric units of pyrrole by esterification of acyl chloride functionalized SWCNTs and N-(6-hydroxyhexyl)pyrrole. In the second step, the PPY/SWCNTs composites are obtained by copolymerizing the pyrrole monomer with the pyrrole units grafted on SWCNTs surface using controlled potential electrolysis. The composites were further characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results showed good electrochemical charge storage properties for the synthesized composites based on PPY and SWCNTs covalently functionalized with pyrrole units making them promising electrode materials for high power supercapacitors.

Electrocapacitance of hybrid film based on graphene oxide reduced by ascorbic acid

Abstract A simple chemical approach was employed to reduce graphene oxide in order to fabricate electrode coatings in close correlation with industrial production standards for supercapacitors. The morphology, structure, thermal stability and the residual oxygen functional groups in chemically reduced graphene oxide were analyzed. Cyclic voltammetry and charge/discharge measurements were employed to study the electrochemical performance of the coatings as a function of active material loading. The results showed an increase in the specific capacitance for chemically reduced graphene oxide-based coatings in comparison to commercial activated carbon, while the desired value needs to be optimized with respect to the conductivity of such materials.

Factorial electrochemical design for tailoring of morphological and optical properties of Cu2O

ABSTRACT The electrodeposition of cuprous oxide (Cu2O) onto FTO-coated glass substrate was studied by using a statistical approach in order to control the Cu2O morphology and optical properties. The factorial design considered four electrodeposition conditions at two representative levels as input variables (electrolyte temperature and pH, deposition potential and duration) and the deposition charge and morphology of obtained Cu2O as the output variables. The morphology analysis showed the highest influence on crystal shape was exhibited by electrolyte temperature and pH, reaching significance levels of 95 and 98%, respectively. Temperature as low as 35°C and pH 12.2 results in cubic morphology, while other parameters result in octahedron shape. The highest absorbance was exhibited by the Cu2O with cubic morphology.

Graphene-Based Coatings for Dental Implant Surface Modification

Among the most promising nanomaterials, an extensive emphasis was drawn onto graphene-based ones for biomedical applicability, being triggered by its exotic properties such as biocompatibility, electric conductivity, and transparency, excellent aqueous processability, amphiphilicity and surface functionalisation degree. The tuneable chemistry and the excellent mechanical, tribological, as well as corrosion properties of graphene-based materials have indicated their potential applications in implant material. Given the growing demand for designing advanced new implant surfaces to control the interactions with the surrounding biological environment in order to improve their biocompatibility and bioactivity and enhance their corrosion resistance, this chapter highlights the approaches for surface modification of dental implants with graphene nanomaterials as surface coatings.