OPTIMIZATION OF TRANSITION-METAL INCLUSIVE CARBON AEROGELS FOR ELECTROCHEMICAL ENERGY APPLICATIONS

Author

Allen Dalton Davis, Pittsburg State UniversityFollow

Date of Award

Winter 12-15-2023

Document Type

Thesis

Degree Name

Master of Science in Chemistry (MSChem)

Department

Chemistry

First Advisor

Dr. Ram Gupta

Second Advisor

Dr. Charles Neef

Third Advisor

Dr. Khamis Siam

Fourth Advisor

Dr. Timothy Dawsey

Keywords

Aerogel, Water Splitting, Oxygen Evolution, Hydrogen Evolution, Transition Metal

Abstract

The ever-growing need for energy alongside rising concerns for climate change demands the development of renewable energy technologies. Hydrogen fuel cells are a promising technology that can serve to either supplement energy generation or act as a lone power source. Yet for these devices to be truly green, the hydrogen that serves as fuel must be procured from a renewable resource. Electrolytic water splitting is a process that allows for the dissociation of water into H₂ and O₂. For this process to be practical, the electrolyzer needs to demonstrate high efficiency and stability, as well as a low overhead cost. Towards this end, transition-metal-based electrocatalysts demonstrate the desired properties.

In this study, transition-metal inclusive carbon aerogels (RF-CT_m) were initially synthesized by adding nickel acetate (RF-CNi), cobalt acetate (RF-CCo), or a 1:1 weight ratio of both (RF-CCoNi) to a resorcinol-formaldehyde (RF) hydrogel synthesis. The resulting hydrogels were then lyophilized to create their respective aerogels, followed by a calcination process to carbonize them. After synthesis, the various samples were employed towards electrode construction for use as bifunctional electrocatalysts. Furthermore, the initial success of RF-CCoNi encouraged the creation of more samples, which modified the wt.% of the 1:1 metal mixture added to the hydrogel synthesis.

Initial electrochemical testing demonstrated that the materials possessed a high affinity for the oxygen evolution reaction, with RF-C, RF-CCo, RF-CNi, and RF-CCoNi producing low overpotentials of 320, 360, 330, and 310 mV respectively. Additionally, these materials processed the reaction at a high rate, with corresponding Tafel slopes being 79, 65, 65, and 47 mV/dec. Meanwhile, the material provided solid results for the hydrogen evolution reaction, demonstrating overpotentials of 236, 207, 202, and 141 mV alongside Tafel slopes of 203, 168, 142, and 131 mV/dec. Considering the promising results of RF-CCoNi, further testing explored the adjustment of overall metal content added to the aerogel. The resulting samples, delineated as RF-CCoNi 25%, RF-CCoNi 50%, RF-CCoNi 75%, and RF-CCoNi 150% demonstrated oxygen evolution and hydrogen evolution overpotentials of 310, 370, 360, 360, and 188, 134, 158, 340 mV each. The results from these experiments advocate that RF-CCoNi aerogels possess desirable properties as a bifunctional electrocatalyst for water electrolysis.

Recommended Citation

Davis, Allen Dalton, "OPTIMIZATION OF TRANSITION-METAL INCLUSIVE CARBON AEROGELS FOR ELECTROCHEMICAL ENERGY APPLICATIONS" (2023). Electronic Theses & Dissertations. 467.
https://digitalcommons.pittstate.edu/etd/467