Amorphous Versus Nanocrystalline RuO2 Electrocatalysts: Activity and Stability for Oxygen Evolution Reaction in Sulfuric Acid

Ruthenium oxide (RuO2) electrocatalysts possessing high activity and stability are needed to sustain the oxygen evolution reaction (OER) under harsh anodic conditions in acidic water electrolysis systems. Herein, we report the activity and stability of RuO2 particles coated on a Ti-fibre felt substrate. Amorphous RuO2 particles of low crystallinity have large electrochemically active surface areas (ECSAs) and high OER activity, but are unstable during the OER in 0.1 M H2SO4. However, complete thermal decomposition of a RuCl3 precursor solution at temperatures above 250 C-degrees yields RuO2 particles with enhanced crystallinity and greater resistance to dissolution under anodic conditions in H2SO4. An optimum calcination temperature of 350 C-degrees produces RuO2 nanoparticles on a Ti-felt with balanced ECSAs and high crystallinity, while simultaneously achieving high OER activity and enhanced stability. The optimized nanocrystalline RuO2/Ti-felt(350) electrocatalyst was stable throughout 48 h of operation at 50 mA cm(-2) at pH 1.0 and delivered a stability number greater than 1 x 10(5), which is comparable to the value provided by more costly IrO2 electrocatalysts.