Seminar Details

Seminar Title
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Evolution of porosity and nanostructure in preceramic polymer derived nanoporous particulates
Seminar Type
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Synopsis Seminar
Department
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Ceramic Engineering
Speaker Type
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Student
Speaker Name
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Ipsita Priyadarshini Swain
Date  &  Time
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07 May 2021  10 a.m.
Venue
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ONLINE MODE THROUGH MS TEAM; Meeting Code: zdek5g9
Contact
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Prof Shantanu K Behera, BeheraSH@nitrkl.ac.in
Abstract
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Inert pyrolysis of Si-containing polymers affords multifunctional amorphous ceramics. Enhancing the textural properties of these materials, including porosity, surface area and nanostructure, can enable a wide range of applications, especially in energy storage devices such as ultracapacitors and Li ion batteries. However, control of the pore size distribution and retention of the high surface area at higher temperatures are engineering challenges that need to be met by design of novel nanostructures and processing methods. The current work explores a novel, yet versatile, method for the fabrication of a high surface area ceramic hybrid with controlled textural properties. In a typical process, the nanoporous hybrids were fabricated by coating the liquid preceramic polymer solutions around nanoparticulate templates. The template acts as a mechanical support substrate and limits shrinkage of the PDC during the polymer to ceramic conversion. Nanoparticulate boehmite and nanocarbon powders were used as templates around which preceramic polymer was coated yielding ceramic hybrids with a retention of porosity, increasing the specific surface area (SSA) up to 260 m2 g-1. The final microstructure of the SiOC produced depends on many factors, including the polymer chemistry, pyrolysis temperature, and heating rate. Studies were performed by varying the above parameters to explore their effect on the microstructures. The unique SiOC structure in the coating, comprising of SiO2 based nanodomains (1-5 nm) and turbostratic carbon layers provided opportunities to create different levels of porosity by etching away the SiO2 domains. In this process, such carbon hybrid materials have shown SSA between 900-2000 m2 g-1 with a major part of the pores being microporous (< 2 nm). Highly ordered carbon structures and pores in the range of 1 nm were clearly seen in the high resolution transmission electron microscopy. The high specific surface area, optimal pore size distribution, and the ordered carbon structures formed in the carbon hybrid made the material suitable for electrode materials in electrical double layer capacitors. The materials exhibited nearly rectangular voltammograms in cyclic voltammetry studies across moderate to high voltage scan rates, indicating ideal capacitive behavior and a value as high as 333 F g-1 of specific capacitance in aqueous electrolyte.