Electronic Theses and Dissertations

Identifier

3750

Date

2016

Date of Award

7-21-2016

Document Type

Thesis

Degree Name

Master of Science

Major

Physics

Concentration

Materials Science

Committee Chair

Sanjay R Mishra

Committee Member

Muhammad S Jahan

Committee Member

Jingbiao Cui

Abstract

Spinel Co3O4 exhibit remarkable photo and electro-chemical properties. Combined with its cost effectiveness and wide abundance, Co3O4 has emerged as a promising candidate for pseudocapacitor, fuel cell, lithium ion batteries, water splitting and energy applications. It is well documented in the literature that the pseudocapacitive performance of oxides depends on many factors such as type of oxide, surface area and morphology, electrolyte, temperature etc. In view of this, the present work delineates efforts to understand the effect of morphology on the electrocapacitive behavior of Co3O4 nanostructured particles. The systematic morphological changes in Co3O4 is achieved by varying hydrolyzing agent, urea content during the hydrothermal synthesis of particles. Morphology and size analysis using scanning electron microscopy (SEM), show hierarchical structures namely plate like architecture and brush like structures of particles. The electrochemical measurements are performed using standard three-electrode system with 3M KOH electrolyte via cyclic voltammetry and galvanostatic charge-discharge methods. Amongst the Co3O4 studied, Co3O4-U0.37 displayed moderate surface area (50.10 m2/g), highest specific capacitance (764 F/g at 5mV/s) and energy density (19.56 Wh/kg). The specific capacitance of all Co3O4 decreased with the increase in scan rate. The cyclic stability of Co3O4-U0.37 is studied up to 5,000 cycles and about 64% retention in charge storage capacity was observed. The superior electro-capacitive behavior of the Co3O4-U0.37 is attributed to high surface area, brush like structure, and high electrical conductivity amongst studied Co3O4. In conclusion, it is demonstrated that high specific capacitance is achievable in the same oxide material by the tight control of morphology of the material. The low hydrolyzing concentration aided in producing high surface area architecture.

Comments

Data is provided by the student.

Library Comment

dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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