Recent advances in Ru-based electrocatalysts for oxygen evolution reaction

The oxygen evolution reaction (OER), as a four-electron transfer process with large overpotential loss that is also kinetically sluggish, is one of the most crucial electrochemical processes to convert renewable energy into chemical fuels. Ruthenium (Ru)-based electrocatalysts for the OER have several advantageous features including high activity, pH-universality and the lowest price in the noble metal family. However, the instability of Ru-based catalysts in the OER is a central hurdle limiting their widespread application. This review focuses on recent developments made in the field of Ru-based OER catalysts. In the coverage, first the characteristics of Ru-based OER catalysts such as the OER mechanism, intrinsic activity and stability issue are discussed. Then, recently reported Ru-related catalysts falling in the Ru metal and Ru compound subclasses are described with special emphasis being given to a discussion of activity/stability-enhancing strategies. Finally, several challenges and future perspectives in this field are summarized. It is anticipated that this review will promote a better understanding of Ru-based OER catalysts and lead to new strategies to design active and stable Ru-materials.