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Title:	Graphitic carbon nitride and bismuth vanadate-based photoelectrodes for solar water splitting
Authors:	Javad Safaei (P88892)
Supervisor:	Mohd Asri Mat Teridi, Dr.
Keywords:	Solar cells Photoelectrochemistry Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	27-Nov-2018
Description:	Solar cells cannot generate electricity during night. One of the approaches to tackle this challenge is to deploy photoelectrodes that split water into hydrogen and oxygen using sunlight. Hydrogen can be further employed directly as a fuel, being reacted with CO2 for producing other hydrocarbon fuels, or to be used in fuel cells. Being a two dimensional semiconductor, g-C3N4 became recognized in the field of photocatalysis due to its environmentally friendly nature, high stability, and excellent redox potentials. However, the research on g-C3N4-based electrodes is not fully developed due to difficult thin film fabrication methods. This work is based on five papers. Each paper utilizes a range of characterization methods to study the synthesized materials. Some of these methods include XRD for phase analysis, FTIR and XPS for studying chemical bodings, EDX for elemental analysis, FESEM and AFM for morphological analysis, UV-Vis and PL for probing optical properties, and LSV for studying the actual performance of electrodes and also their responses to external bias. The first paper gives a detailed literature review on the methods of fabricating g-C3N4 thin films with applications in water splitting, solar cells, and supercapacitors. The second paper is on the fabrication of g-C3N4 thin film using a simple spin coating method. Exfoliated g-C3N4 demonstrated a significantly higher photocurrent and also depicted a more uniform thin films compared with unexfoliated g-C3N4. The third paper is on developing heterojunction photoelectrodes via g-C3N4 and BiVO4. TiO2 was also utilized as electron extraction layers with BiVO4 but demonstrated lower photocurrent response compared with g-C3N4. This is principally due to the formation of oxygen vacancy sites by g-C3N4 that improved the chemisorption and also the charge transportation properties of BiVO4. The fourth paper is on optimizing g-C3N4/BiVO4 via incorporating molybdenum into BiVO4. Molybdenum not only increased charge carrier mobility of BiVO4 but also reduced its band gap down to 2.24 eV. The optimized heterojunction demonstrated photocurrent of ~0.8 mA/cm2 at 1.23 V vs. RHE that is the highest among g-C3N4-based Z-scheme photoelectrodes. The last paper is on studying different types of annealing on BiVO4 using furnace and microwave annealing. The enhanced heat absorption of microwave annealing increased the crystallinity and light absorption of BiVO4 that nearly resulted in a double photocurrent response compared with furnace annealing. This work contribute to the utilization of g-C3N4 in photoelectrochemical devices. Moreover, the contribution can be to the field of materials science, especially pertaining to solar energy conversion and storage, using g-C3N4 and BiVO4.,Master of Science
Pages:	225
Call Number:	TK2960.S234 2018 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Solar Energy Research Institute / Institut Penyelidikan Tenaga Suria (SERI)

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