Metal Organic Frameworks for Energy Storage Devices
Derived from the self-assembly of metal ions and organic linkers, MOFs are promising materials for devices such as fuel cells and batteries due to their intrinsic high surface area, periodicity, and thermal stability. However, most MOFs exhibit low conductivity, owing to the poor orbital overlap between the metal ion and the ligand. We apply chemical design principles such as the use of more covalent metal-linker bonds, pi-pi interactions, and host-guest chemistry to understand and promote electron transport. Using experimental data and calculations, we also use MOFs for enhancing the energy density and the lifetime performance of lithium sulfur batteries. We take advantage of the synthetic modularity of MOFs to install anchoring sites for polysulfides, which can prevent sulfide leaching and lower the energetic barrier for cycling. Moreover, the rich host-guest chemistry and high crystallinity of MOFs offer molecular models for elucidating cycling mechanism that is difficult to obtain in conventional electrode materials.
Small Molecule Activation by Molecular Catalysts
Our aim is to develop new and improved molecular electrocatalysts, utilizing non-precious metals, for small molecule activation and catalysis in the area of energy research and environmental chemistry. We are currently interested in the interplay between transition metal centers and ligand sphere interactions in catalytic carbon dioxide and proton reduction. Inspired by the elegant designs of active site in metalloenzymes, we will employ strategies that create protected catalytic pockets and flexible coordination environments. We rigorously analyze the mechanistic pathways in our catalytic systems from a kinetic and thermodynamic perspective. By understanding the steps and reactive intermediates involved in catalytic turnover, we hope to provide a framework for rational design of earth abundant catalysts.
Hybrid Metal-Carbon Systems For Artifical Photosynthesis
We develop solid state photocatalysts and electrocatalysts to utilize renewable solar energy and electricity for energy conversion and environmental applications. Our goal is to understand the complex interactions occurring at the solid-liquid-gas interfaces during catalysis. We tune the properties of our porous substrates such as surface area, porosity, chemical composition, and mesostructure to probe the solution dynamics. For instance, we aim to understand the relationship between substrate properties and catalytic CO2 reduction activity by systematically tuning the carbon aerogel, a porous carbon foam composed of graphitic sheets, and determining product distributions and yields. Other projects include studying structure-activity relationships in metal-carbon particles for reducing CO2 and other carbon precursors to fuels and developing novel metal sulfide catalysts for hydrogen evolution reaction