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

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