材料科学与化学工程学院学术报告——Thermo-iono-electronic materials: Functional oxides in gas separation and energy harvesting
报告人：Prof. Dr. Armin Feldhoff
Prof. Armin Feldhoff got his PhD degree from the Martin-Luther University Halle-Wittenberg (Germany) in 1997. He was Postdoctoral associate at the Department of Materials Science and Engineering at Cornell University in Ithaca, NY (USA) and the Centre d’Études de Chimie Métallurgique of the CNRS in Vitry sur Seine (France). Since 2003, he has been the Head of Nanostructure Laboratory, research staff member, and lecturer at the Institute of Physical Chemistry and Electrochemistry of the Leibniz Universität Hannover (Germany). In 2012, he has been appointed as an Extraordinary Professor at the Faculty of Natural Sciences of the Leibniz Universität Hannover. Prof. Feldhoff has published almost 150 papers in international peer-reviewed journals including Angewandte Chemie (International Edition), ACS Catalysis and Chemistry of Materials. His research focuses on solid state chemistry, gas permeation membranes (oxygen, hydrogen, helium), thermoelectrics, photocatalysis, energy harvesting, 2D nanomaterials, complex oxides (perovskites, Ruddlesden-Popper phases, spinels), metal-organic framework materials, zeolithes, nanoparticles, nanofibers, ceramics, transmission electron microscopy, scanning electron microscopy, X-ray diffraction. He is acting as associate editor of Energy Harvesting and Systems (de Gruyter) since 2013, and the Journal of Electronic Materials (Springer) since 2015.
It is proposed to look at energy conversion from the point of view of thermo-ionic-electronic (TIE) materials or systems. In addition to ionic and/or electric charge carriers, entropy is considered as further basic quantity being transported through the material or system if the TIE is simultaneously placed in gradients of temperature and electrochemical potential (ionic and/or electronic). In the basic transport equation, the TIE appears as tensor, which is a major advantage over the concept of the so-called thermodynamics of irreversible processes. The role of energy and its conversion is easily understood by the flux of entropy, ionic charge carriers, and electronic charge carriers at their respective local potentials, which are the temperature, the ionic electrochemical potential, and the electronic electrochemical potential. Conversion of energy is easily understood as the loading of energy from entropy current (thermal energy) to ionic current or electronic current (both electrochemical energy) or vice versa. Analogies between the Soret coefficient (thermo-ionic), the Seebeck coefficient (thermoelectric) and the ionic transfer number (ionic-electronic) become evident. The latter plays an important role in the context of the mixed ionic-electronic conductors (MIECs), which can be considered as TIEs under isothermal conditions and are of potential use in gas separation membranes. Also the thermoelectric (TE) coupling is considered to some detail with a focus on energy harvesting.