Research

Realizing new energy technologies based on photochemistry and electrochemistry requires developing materials with properties that increase device efficiencies and performance, and in particular understanding how the molecular and material structure can be tuned to achieve these properties. The key processes underlying these technologies involve heterogeneous charge transfer induced by either light or electrical potential. Our particular emphasis is on charge transfer processes at interfaces between inorganic solids and molecules in solution. Computational and theoretical techniques provide powerful tools to gain atomic-level insight into these properties that is difficult to obtain experimentally, particularly in these complex non-uniform environments.

The Gieseking group develops and implements multi-scale approaches combining quantum mechanical and classical molecular dynamics methods to develop understanding of the photochemical and electrochemical properties and dynamics of materials with applications in energy technologies. Although our work involves a broad range of computational approaches, our development efforts focus primarily on semiempirical methods, which can predict charge-transfer energies more accurately than typical DFT functionals due to their lack of self-interaction error at a substantially lower computational cost.

The goal of our work is to use our computational tools, in collaboration with researchers in experimental materials synthesis and characterization, to develop material design principles that will aid in accelerating the development of materials with controlled properties.

Photochemistry and Excited-State Dynamics

Storing solar energy as chemical fuels is critical to reduce our dependence on fossil fuels and meet increasing energy demands. Photocatalytic synthesis of these fuels typically involves photoinduced electron transfer between the catalyst and the reactant molecule, which can occur via two mechanisms: (1) direct excitation to a charge-transfer state, and (2) an indirect process in which excitation of the metal generates hot charge carriers, which transfer to the acceptor.

We are particularly interested in photocatalysis involving plasmonic metal nanostructures and noble metal nanoclusters because of their strong and highly tunable absorption spectra. Our work on understanding the excited-state dynamics in these systems is aimed toward understanding the structural features that influence the mechanism, yield, and lifetime of the charge-transfer state to enable rational tuning of these structures to enhance photocatalysis.