Hosted by: 'Mingzhao Lu'

Harvesting energy directly from sunlight as nature accomplishes through photosynthesis is a very attractive and desirable way to solve the energy challenge. Many efforts have been made to find appropriate materials and systems that can utilize solar energy to produce chemical fuels. One of the most viable options is the construction of a photoelectrochemical cell that can directly utilize solar energy to drive chemical reactions (e.g. reduction of water to H2, reduction of CO2 to carbon-based molecules). For successful construction of photoelectrochemical cells, simultaneous developments of photoelectrodes, which will efficiently capture photons to generate and separate electron-hole pairs, and catalysts, which will facilitate the use of photogenerated electrons and holes for desired interfacial charge transfer reactions, are necessary. Furthermore, optimally interfacing photoelectrodes and catalysts is critical because the photoelectrode/catalyst interface can govern the overall efficiency of the integrated photoelectrode system. Our research group has been developing new electrochemical synthesis conditions to produce semiconductor electrodes and catalysts with precisely controlled compositions and architectures. In this seminar, we will discuss synthesis and properties of a few promising photoelectrode and catalyst systems for use in solar energy conversion. New synthesis strategies to improve photon absorption, charge transport properties, and catalytic properties will be presented. We will also discuss various strategies to increase the overall utility and efficiency of the photoelectrochemical cells, which include our new results on electrochemical and photoelectrochemical biomass conversion.

Hosted by: 'Anibal Boscoboinik'

Abstract: Solar is becoming increasingly economical, aided by rapidly declining panel cost and increases in energy efficiencies. As solar gains momentum, electrochemical processes in which solar electricity can be used to transform readily available resources such as water and carbon dioxide to create fuels and high-valued chemicals represents an opportunity ripe for development. Presently, these transformations are not yet cost-effective, because of the slow kinetics of the oxygen evolution reaction (OER). Research efforts in the past decade have attributed this inefficiency to the imperfect stabilization of the intermediates; even commercial IrO2 catalysts have limitations. I will present an experimental assessment of this hypothesis on model single-crystalline oxide catalysts. Advances in thin-film deposition developed in the past few decades in the microelectronic community can now enable single-crystalline transition-metal oxides to be routinely grown with high structural perfection. We utilize these advances to experimentally examine the relationship between surface adsorption and OER on rutile IrO2 and perovskite SrIrO3. I will discuss the implications of these studies, including mechanistic insights and how to explore novel oxide phases that are not accessible via thermochemical means for electrocatalysis applications. Biography: Jin Suntivich is an assistant professor in Materials Science and Engineering at Cornell University. Jin received B.S. in Materials Science and Engineering, and B.A. in Integrated Science from Northwestern University, Sc.D. in Materials Science and Engineering from MIT, and postdoctoral fellowship from Harvard University. At MIT and Harvard, Jin's research focused surface science investigations of oxide catalysts for electrochemical/chemical transformations of small molecules including reactions between oxygen, water, and methanol. At Cornell, Jin's group focuses on applying thin-film deposition and self-assembly synthesi