Discovery and Optimization of Multi-Cation Nitride Semiconductors via Reactive Sputtering for Photoelectrochemical Water Splitting
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Beschreibung
This thesis focuses on the development and application of novel semiconducting transition metal nitride materials for photoelectrochemical (PEC) water splitting and renewable hydrogen production. PEC water splitting is a promising approach to
generating green hydrogen, which is considered a sustainable energy source critical for mitigating climate change. However, identifying efficient photoanode materials remains a challenge due to the complex water oxidation process. Although transition
metal nitrides offer potential as high-performance photoanodes, their experimental exploration has been limited by challenging synthesis conditions and their low natural occurrence. To address these issues, novel multi-cation nitride and oxynitride
semiconductors are synthesized by reactive magnetron co-sputtering and nitridation techniques, followed by comprehensive material characterization, including structural, chemical, and optoelectronic analyses to assess the functional properties
of these materials. The findings highlight the potential of these nitride phases for enhanced charge transport, bandgap tuning, defect engineering, and overall photoelectrochemical utilization, as well as their application as high-index materials for
optical applications. By providing insights into the synthesis and functionality of multi-cation transition metal nitrides, the results presented here contribute to the overall goal of identifying efficient photoanode materials. This work advances the fundamental understanding of these novel materials and their role in enabling sustainable hydrogen production through solar water splitting.
This thesis opens with an introduction to solar water splitting using nitride semiconductors, the fundamentals of photoelectrochemistry, and charge transport in semiconductors.
It then covers the synthesis and properties of nitride materials, focusing on tantalum-based semiconductors and their performance-limiting defects. The subsequent chapters detail the synthesis and characterization tools, focusing on methods
and experimental systems used within this work to evaluate the structure, composition, and optoelectronic properties of new materials. Next, two novel solid solution material systems are synthesized and investigated: bixbyite-type zirconium tantalum
oxynitride and hafnium tantalum oxynitride. Next, Ti-doped Ta3N5 photoanodes are investigated, with particular emphasis on defect engineering and photoelectrochemical optimization, followed by a combinatorial approach to explore Hf-doped tantalum
nitride thin films.
Autor*in
Laura Idoya Wagn
Themen in »Discovery and Optimization of Multi-Cation Nitride Semiconductors via Reactive Sputtering for Photoelectrochemical Water Splitting«
semiconductor reactive sputtering nitrides