Three energy-related studies are described in this thesis (1) studies on the capability of conducting polymers (CP) to store electrochemical energy, (2) studies on the stress evolution of conducting polymers during their use, and (3) studies on nanostructured metal surfaces and their use in the electrochemical reduction of CO2. (1) Electrochemical energy storage (EES) technology was explored using composites based on CPs such as polypyrrole doped with redox-active moieties (pPy[Redox]). Anthraquinones, viologens, nitroxyls and lignosulfonates were investigated. Viologens were incorporated into a pPy film via two approaches: covalent linkage to a pyrrole monomer or as a dopant bound by electrostatic interactions. The use of viologen as dopant in CPs enables a cell emf of 1V. Anthraquinones and lignosulfonates also were tested as anode and cathode dopants, respectively, which enabled the chemical synthesis of pPy[Redox] powders in gram quantities, a significant improvement over sample quantities generated electrochemically with other dopants (few micro or milligrams). (2) Various applications of CPs are based on their ability to undergo reversible redox chemistry, which is accompanied by influx or efflux of counter ions and associated solvent molecules. This repetitive flux of ions/solvent into and out of the film results in its shrinking/swelling, eventually resulting in delamination and device failure. The stress as a function of applied potential was studied in situ in thin films of CPs doped with redox-active molecules. These measurements were correlated to changes in mass as a function of potential using an electrochemical quartz crystal microbalance (EQCM). The correlated stress-mass changes were used to identify the mechanism by which pH-dependent redox-active dopants attenuate the stress response of different pPy[Redox] systems. (3) Electrochemical reduction of CO2 was studied at nanostructured copper and tin surfaces. Three-dimensional foam electrodes of copper and tin were electrochemically synthesized with unique pore-channel structures as elucidated from microscopy and electrochemical measurements. Both metals were used as electrocatalysts for the electrochemical reduction of CO2 and were found to have novel, often superior performance than their planar counterparts. Electrochemical and structural characterization studies were performed to explain the observed phenomena.
SEN, SUJAT,
"Electrochemical applications of conducting polymers and nanostructured metals"
(2014).
Chemistry Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0H130C4
