Active and durable R2MnRuO7 pyrochlores with low Ru content for acidic oxygen evolution
Dmitry Galyamin, Jorge Torrero, Isabel Rodríguez‐García, Manuel J. Kolb, Pilar Ferrer, L. Pascual, Mohamed Abdel Salam, Diego Gianolio, Verónica Celorrio, Mohamed Mokhtar, Daniel García Sánchez, Aldo Saul Gago, K. Andreas Friedrich, M.A. Peña, J. A. Alonso, Federico Calle‐Vallejo, M. Retuerto, Sergio Rojas
Abstract
Abstract The production of green hydrogen in water electrolyzers is limited by the oxygen evolution reaction (OER). State-of-the-art electrocatalysts are based on Ir. Ru electrocatalysts are a suitable alternative provided their performance is improved. Here we show that low-Ru-content pyrochlores (R 2 MnRuO 7 , R = Y, Tb and Dy) display high activity and durability for the OER in acidic media. Y 2 MnRuO 7 is the most stable catalyst, displaying 1.5 V at 10 mA cm −2 for 40 h, or 5000 cycles up to 1.7 V. Computational and experimental results show that the high performance is owed to Ru sites embedded in RuMnO x surface layers. A water electrolyser with Y 2 MnRuO 7 (with only 0.2 mg Ru cm −2 ) reaches 1 A cm −2 at 1.75 V, remaining stable at 200 mA cm −2 for more than 24 h. These results encourage further investigation on Ru catalysts in which a partial replacement of Ru by inexpensive cations can enhance the OER performance.