Recent demand for sustainable energy sources have led to active research on advanced materials/devices.
Electrochemical catalytic activity is one of the key mechanisms for fuel cell and hydrogen storage operation. Yet, the fundamental understanding of the oxygen evolution reaction (OER) is rather limited so far. The research team led by Prof. CHOI focused on fabrication of high quality single crystalline transition metal oxide thin film samples to unveil the fundamental physical/chemical mechanism for the OER activity. Introducing atomic-level control of elemental defects during pulsed laser epitaxy (PLE), a strong correlation between the lattice/electronic structure and electrocatalytic activity could be deduced. In particular, the structural phase transition from an orthorhombic to a tetragonal perovskite SrRuO3 resulted in substantial modification in the electronic structure, which led to a 30% reduction in the overpotential for the OER activity. Such change was explained systematically, in terms of hybridization within the Ru-O network, as well as the adsorption probability of oxygen or hydroxyl molecules. Based on this study, the strong correlation within the perovskite oxides which is the key ingredient for many intriguing emergent phenomena, is also considered as an essential part for the energy conversion mechanism. In addition, the study provides microscopic approach in studying the energy-related behavior. This research was published in April issue of Energy & Environmental Science.