Microstructural manipulation and architecture design of carbon-based electrochemical systems

Abstract

Carbon materials are important in electrochemistry. The often cited advantages of carbonaceous materials for electrochemical applications include wide potential working windows, tunable electrocatalytic activity for a variety of redox species, and ease of modifications either by covalent or by noncovalent functionalization. My thesis aims at elucidating the structure-property relationships of carbon-based electrochemical systems, to realize several important applications including electrochemical sensing, catalysis, and energy storage. Specifically, I have examined two classes of carbon-based electrochemical systems: electrospun carbon nanofibers (ECNFs) and redox polymer/carbon hybrid systems. For the first type of material system, I have studied the effects of synthesis condition, architecture design, and post-treatment of ECNFs on their electrochemical properties, and explored the applications of ECNFs in electrochemical sensing and energy storage. I have studied the effects of the carbonization condition of ECNFs on their densities of electronic states (DOS) and electrochemical activities for a wide range of redox-active molecules. Additionally, I have demonstrated ultrawide-range electrochemical sensing using substratesupported continuous high-DOS ECNFs. Furthermore, I have examined microwave-assisted controlled oxidation of high-DOS ECNFs for tailoring their electrocapacitive performance. For the second type of material system, I have investigated the assembly methods and structural manipulation of redox polymer/carbon hybrid systems, and explored their applications in energy storage and catalysis. I have demonstrated that a redox-responsive polymer, polyvinylferrocene (PVF), is useful for noncovalent dispersion and redox-controlled precipitation of pristine carbon nanotubes (CNTs) in nonaqueous media. Moreover, using the stable PVF/CNT dispersion, I have demonstrated solution-based fabrication of PVF/CNT hybrids with controlled nanostructures for supercapacitor applications. Furthermore, I have 'demonstrated local oxidation-induced deposition of PVF onto a carbon fiber matrix for electrochemical control over heterogeneous catalysis.