Demonstrating the Activity and Stability of Conformal RuO2 "Nanoskins" on Technologically-Relevant, 3D Electrode Suports for Water Oxidation in Acid Electrolyte

Tuesday, 3 October 2017: 13:50
National Harbor 6 (Gaylord National Resort and Convention Center)
P. A. DeSario, C. N. Chervin (U.S. Naval Research Laboratory), E. S. Nelson (Pathways Student at US Naval Research Laboratory), M. B. Sassin, and D. R. Rolison (U.S. Naval Research Laboratory)
The commercial viability of many energy-storage and energy conversion devices is compromised by limited efficiency in oxidizing water to generate molecular oxygen (OER). Current state-of-the-art OER anodes fail to meet device-relevant rates of water oxidation at reasonable potentials and suffer from poor stability at the high oxidizing potentials they must adopt to sustain device-relevant O2 generation. Additionally, the high cost and scarcity of the most promising OER catalysts―RuO2 and IrO2―have motivated the search for electrode designs that deploy a nanoscopic amount of the active material while maintaining activity and stability. Most thin film preparations of IrO2 and RuO2 are not amenable with insulating supports and/or non–line of sight geometries. We leverage our solution-based electroless synthetic protocol to deposit conformal, ultrathin films of RuO2 (“nanoskins”) on three-dimensional supports and benchmark their activity under device-relevant conditions. When a self-wired RuO2 thin film is expressed as a nanoshell around the fibers in commercially available SiO2 paper, RuO2@SiO2 electrodes exhibit current densities (10 mA cm–2 @ η=280) 25-times higher than when expressed on planar, conductive supports. By wrapping the fibers with conductive graphitic carbon before nanoskin deposition, we retain the high specific activity of RuO2 nanoskins (40–60 mA mg–1 @ η=330 mV) and preserve the desirable macroscale properties of SiO2 fiber paper: porous, lightweight, flexible, and inexpensive. By efficiently expressing the electrocatalyst, we innately restrict the oxidizing potentials needed to meet a given rate of water oxidation, which diminishes dissolution of the catalyst and corrosion of its underlying current collector, thereby extending anode lifetime.