Date of Award
8-1-2019
Thesis Type
masters
Document Type
Thesis (Restricted Access)
Divisions
advanced
Department
Institute of Advanced Studies
Institution
Universiti Malaya
Abstract
Titanium dioxide (TiO2) nanocrystals in intermediate phase of amorphous and anatase has been successfully synthesized through a simple, low temperature peroxo sol gel approach. Tranmission electron microscopy revealed that the TiO2 nanocrystals obtained have an average diameter of 8-133 nm. The effects of calcination temperature on the morphology and phase transformation were studied by annealing the samples at 200-800 °C. TiO2 nanocrystals annealed at 200 °C with diameter of 12 nm exhibited the highest specific capacitance of 26.46 C g?1 at current density of 0.2 A g?1 in 1M KOH as the electrolyte. The high specific capacity is attributed to the intermediate phase of amorphous and anatase structure which enhanced the redox active sites of the TiO2 nanocrystals. A hybrid material of reduced graphene oxide/titanium dioxide (rGO/TiO2) was successfully synthesized by facile hydrothermal technique. A different amount of GO ratios at 5%, 10%, 20%, and 30% were loaded with TiO2. It is a well-known fact that porous structure and crystallinity of resultant rGO/TiO2 play a crucial role in synergistic effect which facilitate electron transfer movement and reduce the volume changes during a charge-discharge cycle process. Based on the results obtained, an optimum of 10 wt. % GO loading with TiO2 nanocrystals revealed that electrochemical performance achieved the highest specific capacity of 116.70 C g-1 with 0.2 A g-1 among the samples. This result inferred that high efficiency of ion diffusion was obtained with low charge transfer resistance between TiO2 nanocrystals and rGO. The supercapattery was assembled in a configuration of optimized 10% rGO/TiO2 nanocomposites as anode while activated carbon as cathode. The result obtained a superior energy density of 54.37 Wh kg-1 at power density of 420.48 W kg-1. Additionally, the specific capacity still remained at 92% for 3000 charging-discharging cycles under a current density of 1 A g-1. Hence, good life cycle stability, high specific capacity and low charge transfer resistance of rGO/TiO2 nanocomposites electrode suggested that the prepared materials was a promising anode material for supercapattery application.
Note
Dissertation (M.A.) - Institute of Advanced Studies, Universiti Malaya, 2019.
Recommended Citation
Ivy, Heng, "High performance supercapattery with RGO/TiO2 nanocomposites anode and an activated carbon cathode / Ivy Heng" (2019). Student Works (2010-2019). 6566.
https://knova.um.edu.my/student_works_2010s/6566