(Invited) Atomic Layer Deposition-Enabled Functionalization of 3D Nanostructures for Oxygen Electrocatalysis

Abstract

Since the performance of a fuel cell is largely limited by the oxygen reduction kinetics, a rationale design and development of active and durable cathodes is very important. For catalysis per mass, catalysts with a maximized surface area are preferred. This is even more the case for low- and intermediate-temperature solid oxide fuel cells (SOFCs) where the even more sluggish cathodic kinetics should be addressed for commercially acceptable performance. However, electrodes with a high surface area is susceptible to thermal agglomeration during operation at elevated temperatures, leaving the long-term durability of the structure as a major concern.In this talk, I will present our recent efforts to address this issue by atomic-/nano-scale surface treatment of both noble metal (Pt)-based electrodes and more SOFC-relevant cathode materials mainly by the use of atomic layer deposition (ALD). An ultrathin overcoat have proved highly effective in suppressing the sintering kinetics of the underlying electrode structure and thus enhancing the overall cell durability by a significant margin. I also present our recent study successfully demonstrating that even an angstrom-thick oxide overcoat improves thermal durability of high-surface-area electrodes by maintaining the morphology of nanoparticle-decorated (wet-impregnated) cathode structures. The benefits of the surface overcoat is not limited to the enhancement of thermal durability. A discussion on the underlying mechanism of the enhanced electrode kinetics will be also provided.We acknowledge the support from the Korea Institute of Industrial Technology (KITECH) and U.S. National Science Foundation CAREER Award (DMR 1753383).