Solar Energy Conversion
Our inorganic chemistry research program aims to increase the contribution of solar energy to the global energy mix by: (i) making novel materials for converting sunlight to electricity; and (ii) developing metal-based catalysts to efficiently store this solar energy into clean hydrogen fuels.
With proven efficiencies now in excess of 15%, the dye-sensitized solar cell (DSSC) invented by Michael Gratzel in 1991 represents one of the most promising next-generation solar cell technologies. This device relies on electron-transfer from a photo-excited dye to a thin mesoporous semiconducting film on conducting glass. The dye molecule is subsequently reduced by a mediator, which, in turn, is regenerated at the cathode by electrons that migrate through the external load. To help bring the bulk manufacture of DSSCs to fruition, we are improving cell performance and stability by designing robust cyclometalated ruthenium dyes with improved absorptivities in the lower-energy region of the solar spectrum. We are also exploring ways to replace the expensive ruthenium chromophore using first-row transition metals and to replace conventional electrolytes in the DSSC.
The intermittent nature of renewable energy sources creates a fundamental mismatch between supply and demand that can only be bridged by a storage solution. The generation of clean fuels, such as hydrogen, is arguably the best solution for resolving this issue because of their inherently high energy densities and compatibility with our global energy infrastructure. The extraction of hydrogen from water and electricity (i.e., electrolysis) is widely viewed as the most sustainable option for storing clean electricity. Notwithstanding, there are significant kinetic barriers in carrying out this process resulting in efficiency losses.
Our program focuses on the design and synthesis of novel materials capable of mediating the important reactions related to electrolysis. This research includes the development of homogeneous catalysts that enable mechanistic insight into the complicated chemistry that occurs during electrolysis, and the rational design of commercially relevant mixed metal-metal oxide catalysts. A notable highlight from our program is the development of a scalable, facile photochemical technique for accessing amorphous metal oxide catalyst films that circumvents issues such as phase segregation.