Raymond Taziwa

By Raymond Taziwa and Edson Meyer

Ultrasonic spray pyrolysis (USP) methods offer an economical, efficient, and dependable method of depositing nanoparticles (NPs) with consistent crystalline structure and stoichiometry. The need for precise control of structural, morphological, and optical properties has stimulated researches on development spray pyrolysis (SP) methods for depositing titanium dioxide nanoparticles (NPs) and thin films (TF) to substitute traditional sophisticated and expensive wet chemistry methods and solid state techniques. SP methods, as compared to other solid state techniques, offer precise control of the stoichiometry of precursor’s solutions prepared by wet chemistry methods. Moreover, SP methods offer deposition simplicity as the NPs and TFs are deposited at room temperature and pressure. The deposited NPs and TFs are produced in a single‐step route without the need for laborious, expensive purification and excessive annealing procedures. The present chapter offers the experimental challenges and accomplishments experienced while working with the USP systems. Knowledge gathered was key to the development of the present USP system presented herein. This book chapter starts by presenting a review of the current methods available for fabrication of TiO2 NPs and TFs. This chapter also provides a detailed report on the numerous experimental considerations utilized in the optimization of the novel USP system for depositing titanium dioxide NPs and TFs. Finally, the design of the USP system is presented.

Part of the book: Pyrolysis

By Pardon Nyamukamba, Omobola Okoh, Henry Mungondori, Raymond Taziwa and Simcelile Zinya

Titanium dioxide (TiO2) semiconductor nanoparticles are one kind of important and promising photocatalysts in photocatalysis because of their unique optical and electronic properties. Their properties, which are determined by the preparation method, are very crucial in photocatalysis. In this chapter, an overview was carried out on the different methods that are used or have been used to prepare titanium dioxide nanoparticles. There are various methods that can be used to synthesize TiO2 and the most commonly used methods include sol-gel process, chemical vapor deposition (CVD) and hydrothermal method among others. This review will focus on selected preparation methods of titanium dioxide photocatalyst.

Part of the book: Titanium Dioxide

By Luyolo Ntozakhe and Raymond Tichaona Taziwa

It is very important to find new methods for improving the properties of nanostructured materials that can be used to replace the highly expensive and complicated techniques of fabricating ZnO nano-powders for solar cell applications. Pneumatic spray pyrolysis method offers a relatively inexpensive way of fabricating ZnO nanomaterials of controllable morphology, good crystallinity and uniform size distribution, which makes it a good candidate for the production of ZnO nanoparticles. Additionally, it has the advantage of producing ZnO NPs in one step directly on the substrate without the need for other wet chemistry processes like purification, drying and calcination. To that end, the present study emphasizes more on the design and optimization of spray pyrolysis system as well as on the pneumatic spray pyrolysis conditions for the production of carbon-doped ZnO nanoparticles. The un-doped and carbon-doped ZnO NPs were prepared using pneumatic spray pyrolysis employing zinc acetate as a precursor solution and tetrabutylammonium as a dopant. The fabricated un-doped and C-ZnO NPs were characterized for their morphological, structural and optical properties using SEMEDX, XRD and DRS. SEM analysis has revealed that the fabricated un-doped and C-ZnO NPs have spherical shape with mesoporous morphology. The cross-sectional SEM has also revealed that the film thickness changes with increasing dopant concentration from 0.31 to 0.41 μm at higher concentrations. Moreover, the EDX spectra have confirmed the presence of Zn and O atoms in the PSP-synthesized ZnO NPs. XRD analysis of both un-doped and C-ZnO has revealed the peaks belonging to hexagonal Wurtzite structure of ZnO. Additionally, the DRS has revealed a decrease in energy band gap of the synthesized ZnO NPs, with the increase in carbon dopant level.

Part of the book: Zinc Oxide Based Nano Materials and Devices

By Ntalane S. Seroka, Raymond Taziwa and Lindiwe Khotseng

South Africa produces approximately 7 million tons of sugarcane bagasse annually as an agricultural residue, which is treated as waste and its disposal is known to have negative impacts on the environment. To lessen reliance on petroleum and polymers, consideration is given on use of sugarcane bagasse ash as substitute materials for the development of fillers for rubber and other large-scale commodity polymers. This work reports on the mechanical, physiochemical, and structural properties of sugarcane bagasse ash to define the compatibility with the specific polymers that will pave way to the engineering of composites to utilize the potential benefits of these residue-derived fillers. The structural and morphological properties of the untreated and treated sugarcane bagasse ash were performed using XRD, FTIR, and SEM-EDX, respectively. The obtained results confirmed the successful treatment of the sugarcane bagasse ash. The study was successful in showing that sugarcane bagasse ash as potential filler in rubber polymer matrix is a natural resource of silica, which is sustainable and cost-effective, thus should be harnessed for industrial purposes in South Africa.

Part of the book: Application and Characterization of Rubber Materials