In-situ reconstructed Ru atom array on α-MnO2 with enhanced performance for acidic water oxidation

The development of acid-stable oxygen evolution reaction electrocatalysts is essential for high-performance water splitting. Here, we report an electrocatalyst with Ru-atom-array patches supported on α-MnO 2 (Ru/MnO 2 ) for the oxygen evolution reaction following a mechanism that involves only *O and *OH species as intermediates. This mechanism allows direct O–O radical coupling for O 2 evolution. Ru/MnO 2 shows high activity (161 mV at 10 mA cm −2 ) and outstanding stability with small degradation after 200 h operation, making it one of the best-performing acid-stable oxygen evolution reaction catalysts. Operando vibrational and mass spectroscopy measurements were performed to probe the reaction intermediates and gaseous products for validating the oxygen evolution reaction pathway. First-principles calculations confirmed the cooperative catalysis mechanism with a reduced energy barrier. Time-dependent elemental analysis demonstrated the occurrence of the in-situ dynamic cation exchange reaction during the oxygen evolution reaction, which is the key for triggering the reconstruction of Ru atoms into the ordered array with high durability. Proton exchange membrane water electrolysers require the development of active, stable and cost-effective catalysts for water oxidation. Now, a Ru/α-MnO 2 catalyst with in-situ-formed arrays of Ru atoms is presented for acidic water oxidation, which follows the oxide path mechanism and achieves enhanced activity and stability.