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. RuO 2 is touted as one of the superior OER catalysts but only under acidic conditions; RuO 2 electrocatalysts suffer from poor stability under alkaline conditions. In this work, we evaluate three photodeposited RuO x 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 RuO x 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 RuO x for alkaline water electrolysis.

The storage of renewable energy is a pressing challenge to overcome in the transition towards a power grid based on plentiful, yet intermittent energy supplies. The renewables-driven electrolysis ofwater to formhydrogen 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 RuO2 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 RuO2 catalysts outperform their amorphous counterpart, and are stable under alkaline (0.1 M KOH) conditions. This works thus lifts a major hurdle towards the use of RuO2 for alkaline water electrolysis.