A Comparison of Photodeposited RuOX for Alkaline Water Electrolysis

The storage of renewable energy is a pressing challenge to overcome in the transition toward a power grid based on plentiful, yet intermittent energy supplies. The renewables-driven electrolysis of water to form hydrogen fuel is an attractive avenue, but requires better oxygen-evolution reaction (OER) catalysts to be feasible at scale. RuO2 is touted as one of the superior OER catalysts but only under acidic conditions; RuO2 electrocatalysts suffer from poor stability under alkaline conditions. In this work, we evaluate three photodeposited RuOx OER electrocatalysts, all prepared via a scalable photodeposition method. Based on electrochemical and spectroscopic studies (X-ray photoelectron spectroscopy and X-ray absorption spectroscopy), our main findings are that nanocrystalline RuOx catalysts outperform their amorphous counterpart and are more stable under alkaline (0.1 M KOH) conditions. This works thus lifts a major hurdle toward the use of RuOx for alkaline water electrolysis.