Date of Award
Doctor of Philosophy (PhD)
Due to the harsh environment issues such as air pollution and global warming and global energy crisis raised by using fossil fuels, it is urgent to find an alternative sustainable energy source. How to utilize solar energy-the most clean and abundant energy source on earth is challenging. Convert solar energy to clean fuel energy like H2 or hydrocarbons is ideal energy conversion strategy. Thus, design new materials for hydrogen generation or CO2 reduction have attract researcher’s attention.The present study focuses on two types of materials of interest, the first of which is Metal Organic Frameworks (MOFs), including enhancing the light harvesting ability of ZIF-67 via energy transfer from RuN3, electron transfer in hybrid Pt-Ru-UIO-67, Co-Ru-UIO-67 and Ce-TCPP MOF. Since MOFs have potential to be used as photocatalytic materials for artificial photosynthesis due to their unique porous structure and ample physicochemical properties of the metal centers and organic ligands in framework, we also examine the photocatalytic activity of these materials for hydrogen generation. By using the combination of X-ray absorption spectroscopy (XTA), transient absorption spectroscopy (TA), the fundamental roles of hybrid MOF that plays during catalysis were uncovered. The second type of materials that we are interested in is Covalent Organic Frameworks (COFs). A 2D COF with incorporated Re complex was designed, which can efficiently reduce CO2 to form CO under visible light illumination with high electivity (98%). More importantly, using advanced transient optical and X-ray absorption spectroscopy and in situ diffuse reflectance spectroscopy, three key intermediates that are responsible for charge separation (CS), the induction period, and rate limiting step in catalysis were found, which is expected to provide important guidance on designing efficient materials for CO2 reduction, thus facilitating the development of solar to fuel conversion.