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Competitive Oxygen Evolution in Acid Electrolyte Catalyzed at Technologically Relevant Electrodes Painted with Nanoscale RuO2

Author:
DeSario, Paul A., Chervin, Christopher N., Nelson, Eric S., Sassin, Megan B., Rolison, Debra R.
Source:
ACS Applied Materials & Interfaces 2017 v.9 no.3 pp. 2387-2395
ISSN:
1944-8252
Subject:
anodes, carbon, catalysts, electrolytes, foil, oxygen, oxygen production, paper, silica, superoxide anion
Abstract:
Using a solution-based, non−line-of sight synthesis, we electrolessly deposit ultrathin films of RuO₂ (“nanoskins”) on planar and 3D substrates and benchmark their activity and stability for oxygen-evolution reaction (OER) in acid electrolyte under device-relevant conditions. When an electrically contiguous ∼9 nm thick RuO₂ nanoskin is expressed on commercially available, insulating SiO₂ fiber paper, the RuO₂@SiO₂ electrode exhibits high current density at low overpotential (10 mA cm–² @ η = 280 mV), courtesy of a catalyst amplified in 3D; however, the mass-normalized activity falls short of that achieved for films deposited on planar, metallic substrates (Ti foil). By wrapping the fibers with a <100 nm thick graphitic carbon layer prior to RuO₂ deposition (RuO₂@C@SiO₂), we retain the high mass activity of the RuO₂ (40–60 mA mg–¹ @ η = 330 mV) and preserve the desirable macroscale properties of the 3D scaffold: porous, lightweight, flexible, and inexpensive. The RuO₂@C@SiO₂ anodes not only achieve the 10 mA cm–² figure of merit at a low overpotential (η = ∼270 mV), but more importantly they do so while (1) minimizing the mass of catalyst needed to achieve this metric, (2) incorporating the catalyst into a practical electrode design, and (3) improving the long-term stability of the catalyst. Our best-performing anodes achieve state-of-the-art or better performance on the basis of area and mass, and do so with a catalyst density 300–580× less than that of bulk RuO₂. By limiting the oxidizing potential required to evolve O₂ at the electrode, even at 10 mA cm–², we achieve stable activity for 100+ h.
Agid:
5620377