Date of Award

Spring 5-7-2021

Document Type

Thesis

Degree Name

Master of Science in Chemistry (MSChem)

Department

Chemistry

First Advisor

Dr. Ram Gupta

Second Advisor

Dr. Khamis Siam

Third Advisor

Dr. Charles Neef

Fourth Advisor

Dr. John Franklin

Keywords

PANI, Supercapacitors, HER, OER

Abstract

To address increasing energy demands, more energy storage options are needed. N-doped carbon with rich open mesoporous structures are formed by high-temperature activation using potassium hydroxide. The effect of different mass ratios of polyaniline and potassium hydroxide on the microscopic morphology of activated carbon materials was studied. In addition, composite materials of polyaniline and transition metal oxides were synthesized by in-situ polymerization. The surface morphology, pore distribution, specific surface area, and pore structure of these materials were explored by scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) methods, respectively. The results show that all these materials are rich in mesoporous structures. A three-electrode system was used to test the energy storage performance of all these materials. In addition, the transition metal oxides and their composite materials with polyaniline were also tested for their performance as electrolyzed water catalysts. When the mass ratio of PANI and polyaniline is 1:1, the specific surface area of the material was as high as 3259 m2/g, which yielded good supercapacitor energy storage performance, with a specific capacitance as high as 194.3 F/g at a charge-discharge current density of 1 mA/g. In addition, the PANI: KOH (1:1) exhibited excellent rate performance shown through the charge and discharge current density being increased ten times from 3 mA/g to 30 mA/g, while still completing 84.4% charging. In addition, PANI: KOH (1:1) showed good stability as seen after 10,000 charge-discharge cycles since the specific capacitance retention was as high as 92%. PANI/Co2NiO4 and Co2NiO4 coated electrodes exhibited good electrochemical performance, especially as a catalyst for electrolysis of water. The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) exhibited low overpotentials of 145 mV for Co2NiO4 and 320 mV for Co2NiO4, respectively. In addition, both Co2NiO4andPANI/ Co2NiO4showed good electrochemical stability via an 18 hours Chronoamperometry test, as the conductivity of the material did not attenuate but increased by nearly 60%. These results suggest that the porous carbon nanotube synthesized with PANI as the precursor had good electrical double-layer capacitor characteristics and that PANI/Co2NiO4and Co2NiO4exhibited good electrolytic water catalytic performance.

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