A Facile Synthesis of Size-Controllable IrO₂ and RuO₂ Nanoparticles for the Oxygen Evolution Reaction

The efficiency of the water electrolysis process is restricted by the sluggish kinetics of the oxygen evolution reaction (OER). Developing efficient catalysts and their synthesis methods is highly desired to improve the kinetics of the OER and therefore the overall efficiency of the water electrolysis. In this report, we present a facile wet-chemical method for synthesizing IrO₂ and RuO₂ nanoparticles (NPs) for the OER. The nanoparticles were synthesized by reducing metal chlorides in ethylene glycol in the presence of polyvinylpyrrolidone, followed by annealing in air. The particle size was controlled by adjusting the annealing temperature. The activity of IrO₂ and RuO₂ NPs supported on carbon black was investigated by cyclic voltammetry (CV) in alkaline (0.1 M KOH) electrolyte. As-synthesized IrO₂ and RuO₂ NPs showed high OER activity. The IrO₂ NPs exhibited a specific activity of up to 3.5 (±1.6) μA/cm² _oxide at 1.53 V (vs. RHE), while the RuO₂ NPs achieved a value of 124.2 (±8) μA/cm² _oxide. Moreover, RuO₂ NPs showed a mass activity for OER, up to 102.6 (±10.5) A/g_oxide at 1.53 V (vs. RHE), which represents the highest value reported in the literature to date. [Figure not available: see fulltext.]