Fabrication and Optimisation of Engineered Nanostructured Thin Films for Enhanced Photoelectrochemical Applications

Abstract

This thesis presents an extensive study on the development and enhancement of nanostructured photoelectrode materials for photoelectrochemical (PEC) water splitting, a critical area in sustainable energy technology advancement. The research is divided into three focused areas: the development of a robust n-type semiconductor photoanode, the fabrication of heterojunction-based metal oxide semiconductors, and the integration of efficient co-catalysts with photoanodes. The first chapter, which has led to a publication, delves into the fabrication of thin films using radio frequency (RF) sputtering. This process involved an in-depth examination of the factors influencing the films' morphology and phase. A significant development was achieved with the synthesis of vertically aligned Fe2O3 nanorods, which were enhanced by incorporating cadmium oxide (CdO) nanoparticles. This unique combination resulted in a considerable boost in PEC activity, characterised by increased photocurrent density and stability. The innovative corn-like morphology and high crystallinity of these nanorods, combined with the synergistic effect of the CdO co-catalyst, led to improvements in photocurrent generation and stability, which are essential for applications in environmental remediation and sustainable energy conversion. The second chapter, which has also resulted in a publication, explores the creation of a type II nano-heterojunction by integrating HfO2 with α-Fe2O3. Preliminary results indicate that this heterostructure significantly improves charge separation and transport, showing promise for substantial enhancements in PEC performance. The increased photocurrent density and improved photon absorption in the visible spectrum are indicative of the potential improvements this research could provide to PEC systems. The third chapter, which has also resulted in a publication, investigates the deposition of cobalt nanoparticle-based co-catalysts on WO3 thin films. This approach has successfully enhanced carrier separation and interface charge transfer efficiency, leading to a significant improvement in photocurrent density under simulated solar radiation. This achievement marks a development in the field, demonstrating the potential of nanoparticle-based co-catalysts in enhancing the efficiency of PEC systems. In summary, this thesis provides valuable insights and new methods in the study of photoelectrochemical (PEC) water splitting. The research, especially the findings from the first and third chapters, represents important progress in photoelectrochemistry. These contributions pave the way for future developments in sustainable energy technologies.