Chemical Dynamics in Condensed Phases
The focus of our research is understanding the chemical dynamics related to photocatalytic and electrocatalytic reactions. In light of the ever growing energy needs, understanding and employing such reactions are crucial for future solar light harvesting and sustainable energy technologies. The following diagram illustrates our central questions.
Many reactions of interest for photocatalysis occur at interfaces. Two persistent challenges in modern chemistry have been understanding reactions at interfaces and reactions in the excited state. At the nexus of these two resides photoelectrochemical light harvesting (artificial photosynthesis) as a contemporary scientific and technological goal. Chemistry at interfaces is known to be complex and not a mere extrapolation of bulk phenomena. This stems from experimental difficulties in accessing interfacial properties and theoretical challenges in describing them. Simple quantities such as dielectric constant, pKa, local electric field, and molecular polarization, which are reasonably well-understood in the bulk, become complicated to measure and describe for interfaces. A second level of challenge is describing reactions that occur in the excited state, for which the rules of ground-state chemistry often do not hold. For example, the commonplace concepts of acidity and basicity are fundamentally modified for a molecule in the excited state. While these are challenges, they equally open opportunities to engineer and harness the chemistry near an interface and in the excited states. Therefore, a systematic experimental and theoretical effort is desired to understand the physical foundations of interfacial and excited state redox reactions. This general idea drives our research. The diagram below shows how our recent work is inspired by interfacial and redox phenomena.