Center for Functional Nanomaterials Seminar
11 am, CFN, Bldg 735 Conference Room A, 1st Floor
Hosted by: '''Pawel Majewski'''
My research is focused on rational design of materials for efficient electrocatalysis and electrochemical energy conversion and storage. In particular, I am interested in electrochemical reduction of carbon dioxide, a potent greenhouse gas and a contributor to global warming. Given the fact that the CO2 molecule is very stable, its electroreduction processes are characterized by large overpotentials. To optimize the hydrogenation-type electrocatalytic approach, we have utilized nanostructured metallic centers (e.g. Pd, Pt or Ru) in a form of highly dispersed nanoparticles generated within a supramolecular network of distinct N-, S- or oxygen-coordination complexes. Another possibility to enhance electroreduction of carbon dioxide is to explore direct transformation of solar-to-chemical energy using transition metal oxide semiconductors. We showed that, by controlled combination of semiconducting oxides (TiO2 and Cu2O), we were able to drive photoelectrochemical reduction of carbon dioxide mostly to methanol.
Application of mixed-metal oxides as active matrices is important in electrocatalytic oxidation of small organic molecules in low-temperature fuel cells. The oxide's chemical properties and morphology, which favor hydrous proton mobility affect the overall reactivity during oxidation of ethanol (e.g. at PtRu). When metal nanoparticles were dispersed between WO3 and ZrO2 layers, significant current enhancements were observed. The result can be rationalized by the mechanism in which Rh induces splitting of C-C bonds in C2H5OH molecules before the actual electrooxidation.
We also consider nanoelectrocatalytic systems permitting effective operation of the iodine-based dye sensitized solar cells. The ability of Pd or Pt nanostructures to induce splitting of I-I bonds in the triiodide molecules is explored here to enhance electron transfers in the triiodide/iodide-containing 1,3-dialkylimidazolium ionic liquids.