A Systematic Study on Hydrogen Photogeneration Performance of Lanthanide Doped and Nitrogen-Lanthanide Co-Doped Strontium Titanate

The urgent challenges of global warming and the ongoing energy crisis necessitate the development of sustainable and efficient energy gathering and carrying solutions. One promising approach is the use of photocatalysis to convert abundant resources into high-value chemicals using clean solar energy. Hydrogen is recognized as one of the most efficient energy vectors, and its photogeneration from water is a highly researched topic. This thesis investigates the modification of strontium titanate (Strontium Titanium Oxide, STO, SrTiO3) for this purpose, focusing on lanthanide doping and nitrogen-lanthanide co-doping strategies, as well as platinum co-catalyst loading via photodeposition, testing under UV-Vis irradiation. STO is a well-known semiconductor for hydrogen production under UV light, and this research aligns with the recent trend of exploring doping strategies aimed at extending its photoactivity into the visible spectrum. This study explores the effects of cerium, praseodymium, erbium, and ytterbium dopants on STO. The experimental results demonstrate that lanthanide-nitrogen co-doping, especially with platinum co-catalyst loading, significantly enhances the photocatalytic activity of STO. Despite the presence of anatase impurities in co-doped specimens, which complicates the identification of the most effective dopant, erbium emerged as a particularly promising candidate. In terms of hydrogen generation rate, erbium-doped STO showed the highest result of 163.9 µmol g-1 h-1 among the lanthanide-only doped specimens with platinum loading, while the nitrogen-erbium co-doped variant achieved the highest score of 143.4 µmol g-1 h-1 without platinum loading and the second best of 774.7 µmol g-1 h-1 with platinum loading among the lanthanide-nitrogen co-doped specimens. The flower-like morphology, with its high surface area, likely contributed to improved performance across the specimens, and stability tests confirmed the durability of this material over extended periods of photoactivity. While the findings demonstrate promising progress in photocatalytic hydrogen production with STO, further optimization of experimental parameters is required. Refining synthesis parameters to reduce impurities and improve the morphological properties and consistency of specimens, conducting deeper bandgap and band positioning analysis, getting insight into the effective amount of dopant incorporation, testing under visible light or solar conditions, exploring alternative co-catalysts, improving some experimental protocols, and a comparison with undoped STO and nitrogen-only doped STO are recommended for future research. These insights offer a foundation for enhancing the efficiency of STO in hydrogen photogeneration and advancing sustainable energy technologies.