Tahir, AsifAlruwaili, Manal2024-06-232024-06-232024-06-17https://hdl.handle.net/20.500.14154/72329Photoelectrochemical (PEC) water splitting is one of the most promising economic technologies for producing hydrogen (H2) energy, which splits water into oxygen and hydrogen with high efficiency, prolonged stability, and low cost. PEC cells employ semiconductor photocatalysts that utilise and convert solar energy into chemical bonds, which are used to generate stored hydrogen fuel—a sustainable and clean energy source. Traditionally, these cells have been considered holy grails because of their clean energy conversion ability without carbon emissions. Photocatalysts generate electrons and holes as charge carriers under illumination, allowing water- splitting reactions. As part of this research project, we synthesised, developed, characterised, and explored new materials that can achieve water-splitting reactions utilising solar energy. Moreover, we developed new photoanodes to overcome the limited functionality of appropriate n-type semiconductors. This study aimed to design and fabricate new materials that have never been explored before in PEC water-splitting applications. Towards developing stable and visible-light-active photoanodes, we synthesised single-phase TiVO4 for the first time, demonstrating its potential as a novel n-type photocatalyst. The prepared photoanode underwent PEC testing and exhibited a photocurrent density of 0.080 mA cm-2 at 1.23 V (vs. a reversible hydrogen electrode (RHE)), which was stable for up to 110 min. To understand the phase purity and thin-film growth mechanism, the annealing and substrate temperatures were optimised to obtain high-quality crystalline smooth films. Furthermore, we investigated the effect of loading cobalt 2 nanoparticles as a co-catalyst on spray-pyrolysed TiVO4 thin films to fabricate TiVO4:Co composite. We observed a significant enhancement in the PEC performance by carefully optimising the concentration of Co+2 (3 mM). The photocurrent density of TiVO4:Co (3 mM) reached 0.450 mA cm-2 at an applied bias potential of 1.23 V vs. RHE, approximately five times higher than that of bare TiVO4. In addition, the composite exhibited a notable improvement in photocatalytic activity for methylene blue (MB) degradation. To enhance the properties and performance of bare TiVO4 thin films, an underlayer of hydrothermally prepared WO3 was integrated beneath the spray-pyrolysed TiVO4 film. The resulting heterostructure demonstrated notable enhancements in optical, structural, and microstructural attributes, along with an improved photocurrent response. This improvement is attributed to the strategic deposition of a WO3 underlayer, forming a heterostructured composite electrode. This significantly increased the photocurrent density for the WO3/TiVO4 photoanode, reaching a peak of 0.740 mA cm-2 at an applied potential of 1.23 V vs. RHE–approximately nine times that of standalone TiVO4.172enphotocatalystsPhotoelectrochemical (PEC) water splittingsingle-phasephotocurrent densityThesis