Date of Award
10-8-2014
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Applied Science
First Advisor
Ali Shaikh
Abstract
In this fast growing population and industrial revolution, excessive energy consumption has become a great challenge. To overcome the situation in the future it is necessary to utilize cheap and renewable resources to produce environmental-friendly, low cost and efficient energy conversion and storage. Fuel cells and supercapacitors are excellent electrochemical energy conversion and storage systems. The coupling of supercapacitors with fuel cells or batteries has the potential to deliver high power necessary in motor vehicles, cellphones, computers and other useful devices. Modern fuel cells are based on electrochemical combination of hydrogen and oxygen in acidic, neutral and alkaline media to generate electrical energy. The energy can be stored in large quantity using supercapacitors. We have synthesized novel non-platinum based materials of various classes to evaluate their oxygen reduction reaction (ORR) capability as well as supercapacitor activity. The materials include: (1) macrocyclic amide based cobalt complexes combined with multiwalled carbon nanotubes (MWCNTs), (2) cobalt polypyrroles combined with MWCNTs, and (3) dual heteroatom (nitrogen and phosphorus) doped carbon. Detailed electrochemical studies, using cyclic voltammetry (CV), rotating disk voltammetry (RDE) and rotating ring-disk voltammetry (RRDE) reveal that cobalt macrocyclic amides with various pendant groups have profound effect on ORR activity, in terms of four-electron oxygen reduction that generate optimum voltage and high current density. Similar studies with cobalt polypyrroles and dual doped carbon show potential for efficient voltage generation as well as supercapacitor activity. The variation of cobalt content in cobalt polypyrrole, as well as the ratio of the polypyrrole to MWCNTs in the composites has profound effect on these characteristics. Similar variation in dopant concentration in carbon materials, as well as the type of dopant (N, P, B, S, etc.) has shown improved ORR and supercapacitor behavior. Detailed electrochemical studies of these materials are presented in this thesis.
Recommended Citation
Nasini, Udaya Bhasker, "Oxygen Reduction Reaction and Supercapacitor Studies of Cobalt Complexes/Carbon Nanotube Composites and Phosphorous, Nitrogen Doped Carbon Materials" (2014). Theses and Dissertations. 516.
https://research.ualr.edu/etd/516
