Program: Energy and Environment
Department: Chemistry and Chemical Biology
Professor Li and her research team are engaged in design, synthesis, characterization and modification of new materials potentially important for energy storage and conversion. One area of research focuses on the development of hybrid semiconductors. Figure 1 shows two members from a unprecedented class of inorganic-organic hybrid semiconductor materials comprised of sub-nanometer-sized II-VI semiconductor motifs (inorganic component) and mono- or di-amine molecules (organic component). These hybrid materials possess a number of improved and enhanced properties over their parent bulk semiconductors, including broad band-gap tunability and high absorption coefficients, all desirable for optoelectronic applications. They also possess a rich structural chemistry and exhibit very interesting structure related photoemission, thermal expansion and thermal electric properties. More significantly, they show exceptionally strong structure-, rather than size-induced, quantum confinement effect (QCE), and such confinement can be systematically tuned by modifying the composition, crystal structure, and dimensionality of the inorganic motifs. Another area of focus is on microporous metal organic materials (MMOMs). As a subclass of MOFs these materials contain micropores (pore diameter less than 20Å) and demonstrate porosity associated multi-fold functionality that show promise for applications in gas storage, separation and catalysis. Compared to other porous materials such as zeolites and carbon nanotubes, MMOFs demonstrate numerous desirable features. Their crystal structures (e.g. dimensionality, framework connectivity, and topology), compositions (e.g. the type and form of metals and ligands) and pore properties (e.g., pore size and shape, pore volume and the chemical functionality of the pore walls) can be deliberately and systematically tailored to enhance targeted properties and to achieve improved performance. Figure 2 shows a highly porous MMOF structure.
Fig. 1. Hybrid semiconductors made of II-VI
slabs and organic diamine (left) and
mono-amine (right) molecules.
Fig. 2. AMMOF structure composed of M2
paddle wheel SBUs and TED molecules.