Department of Chemistry Seminar: Presentations by PhD Students II



Use of novel substrates for single molecule conductance measurement
Speaker: Qian Zhang

Recently, the unique structural and electronic characteristics of graphene make it an attractive contact for fundamental single-molecule electrical studies. Here we have probed the electrical conductance of a molecular junction based on α,ω-diaminoalkane chains sandwiched between a gold and a graphene electrode. Using an STM based I(s) method combined with density functional theory-based transport calculations, we demonstrated that the resulting attenuation factor is much lower when compared to the standard molecular junction between two gold electrodes. This effect is attributed to asymmetric coupling of the molecule through strong chemisorption at the gold electrode and weaker van der Waals contact at graphene. Moreover, this asymmetric coupling induces higher conductance than that in the same hybrid metal−graphene molecular junction using standard thiol anchoring groups.


Cr-poisoning of La0.6Sr0.4Co0.2Fe0.8O3 in Solid Oxide Fuel Cells and Solid Oxide Electrolysis Cells
Speaker: Meigeng Gao

Solid oxide fuel cell technology demonstrates remarkable achievements over last two decades. Solid oxide fuel cell (SOFC) has high efficiency (over 60%) and fuel compatibility (H2, CO, CH4 etc). Recently, the fuel cell technology has been adapted for tackling the energy storage challenges. A solid oxide electrolyzer cell (SOEC), which has similar components as SOFCs, but working in the regenerative mode, can be used for efficient and economically viable hydrogen/syngas production. Cr-containing steels and alloys are widely applied as interconnects in SOFC/SOEC systems. However, the volatile chromium species evaporate from interconnects, migrate with air stream, deposit within electrodes cathode, and result in the degradation of the electrochemical performance. The research project is focused on the identification of Cr- poisoning mechanism for La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode under the SOFC and SOEC conditions.