Saptarshi Dhibar

Graphene decorated with hexagonal shaped M-type ferrite and polyaniline wrapper: a potential candidate for electromagnetic wave absorbing and energy storage device applications

The development of promising microwave absorbing materials is a booming field of research in both the commercial and defense sectors to prevent electromagnetic pollution, and also to enrich the field of stealth technology. Supercapacitors are a symbol of clean energy storage devices. The present work attends to the preparation of hexagonal shaped magnetic M-type hexaferrite, CuFe10Al2O19 (CFA) by a facile chemical co-precipitation method, and the formation of its composites (graphene/CFA) in the presence of acid modified graphene. An in situ approach was employed for the coating of graphene with CFA. Another nanocomposite (graphene/CFA/PANI) was prepared by the wrapping of graphene/CFA with polyaniline (PANI), which was prepared through the in situ chemical oxidation polymerization of aniline. The prepared multifunctional nanocomposites showed an outstanding and improved microwave absorption property (the maximum reflection loss was −63.6 dB at a thickness of 2.5 mm with a broad absorption range) and electrochemical properties (the highest specific capacitance value was 342 F g−1), in contrast to the pristine graphene and CFA. The addition of PANI also improves the microwave absorption and specific capacitance of the nanocomposites. The formation of the multifunctional nanocomposites and their structural characteristics are discussed thoroughly with their impact on the two different fields of applications i.e. microwave absorbing and energy storage device applications individually.

Polyaniline/HCl/CuCl2/TPU Nanocomposites: Synthesis, Characterization and its Microwave Absorption Behaviour in X-Band

CuCl2-doped polyaniline (PANI)-based microwave absorbing materials were prepared and characterized by different analytical techniques, which confirm the occurance of doping. The electrical conductivity of the nanocomposites was measured by a four-probe method, and the result was explained by considering the complexation between Cu2+ and PANI. Microwave absorption studies were carried out in the X-Band region and discussed with the help of complex permittivity and permeability of the prepared microwave absorbing materials. Microwave absorption result showed that these nanocomposites can be potentially used for various microwave absorbing applications. The thermal stability of the nanocomposites increases due to the incorporation of CuCl2.

Electrochemical behaviour of graphene and carbon nanotubes based hybrid polymer composites

In recent times, the quickly mounting global economy has caused severe environmental problems and excessive utilization of fossil fuels, resulting in important threats to the survival and development of humankind. For that reason, employing sustainable and clean energy in addition to efficient energy conversion and storage technologies is immediately required. It was approximated that the world will require doubling its energy supply by 2050. For this reason, advanced technologies for both energy storage (supercapacitors and batteries) and conversion (solar cell and fuel cell) are being widely studied around the world. Over the last few decades numerous researches are going on the field of carbon nanotubes (CNT) and conducting polymer-based nanocomposites as well as graphene and conducting polymer–based nanocomposites for energy storage applications. The present chapter gives a brief overview of the most recent research on CNT and graphene-based hybrid nanocomposites for electrochemical supercapacitors.