Study of model photocatalysts to optimize water splitting

This project aims to develop a fundamental understanding of photocatalytic (PC) reactions, in particular solar-driven water splitting, through a basic science approach. To this end, we propose to conduct detailed surface science studies using model systems to elucidate the complex mechanisms that underpin PC reactions. The insights we will obtain are intrinsically valuable to the field, yet are also expected to improve the performance of PC reactions, including the efficiency of solar to hydrogen (STH) conversion and the photocatalyst’s stability. Quantum Dots (QDs; their development was recognized by the 2023 Nobel Prize in Chemistry) are semiconductor nanocrystals whose optoelectronic properties can be tuned by varying their size, shape and composition; QD structure can be tailored to optimize light emission or absorption. As such, they are considered as promising building blocks for PC water splitting. Our model systems will consist of single crystal substrates made of the same materials as QDs used in PC reactions. The model experiments will be conducted under ultra-high vacuum conditions, to remove residual contaminants. We will use high resolution scanning tunnelling microscopy (STM, which can attain atomic resolution) to pinpoint active sites, map reaction pathways, investigate the role of defects and study degradation mechanisms. Imaging by STM will be complemented by spectroscopic studies and theoretical calculations. The experiments will be carried out under illumination using suitable radiation sources to underpin photoactivation mechanisms. This approach builds on methods developed by G. Ertl (Nobel Laureate in Chemistry, 2007), the father of Surface Science, who studied model systems in controlled environments to better understand chemical reactions, e.g. heterogeneous catalysis, in particular mapping the details of the Haber-Bosch process in which atmospheric nitrogen is converted into ammonia using an iron catalyst. The proposed research defines a special opportunity, as it “combines” two Nobel-winning fields of research towards a completely new direction. The expected impact includes a fundamental understanding of PC reactions, potential applications in solar fuels and training highly skilled scientists in these increasingly important areas.

This project aims to develop a fundamental understanding of photocatalytic (PC) reactions, in particular solar-driven water splitting, through a basic science approach. To this end, we propose to conduct detailed surface science studies using model systems to elucidate the complex mechanisms that underpin PC reactions. The insights we will obtain are intrinsically valuable to the field, yet are also expected to improve the performance of PC reactions, including the efficiency of solar to hydrogen (STH) conversion and the photocatalyst’s stability. Quantum Dots (QDs; their development was recognized by the 2023 Nobel Prize in Chemistry) are semiconductor nanocrystals whose optoelectronic properties can be tuned by varying their size, shape and composition; QD structure can be tailored to optimize light emission or absorption. As such, they are considered as promising building blocks for PC water splitting. Our model systems will consist of single crystal substrates made of the same materials as QDs used in PC reactions. The model experiments will be conducted under ultra-high vacuum conditions, to remove residual contaminants. We will use high resolution scanning tunnelling microscopy (STM, which can attain atomic resolution) to pinpoint active sites, map reaction pathways, investigate the role of defects and study degradation mechanisms. Imaging by STM will be complemented by spectroscopic studies and theoretical calculations. The experiments will be carried out under illumination using suitable radiation sources to underpin photoactivation mechanisms. This approach builds on methods developed by G. Ertl (Nobel Laureate in Chemistry, 2007), the father of Surface Science, who studied model systems in controlled environments to better understand chemical reactions, e.g. heterogeneous catalysis, in particular mapping the details of the Haber-Bosch process in which atmospheric nitrogen is converted into ammonia using an iron catalyst. The proposed research defines a special opportunity, as it “combines” two Nobel-winning fields of research towards a completely new direction. The expected impact includes a fundamental understanding of PC reactions, potential applications in solar fuels and training highly skilled scientists in these increasingly important areas.