A review on fundamentals for designing stable ruthenium-based catalysts for the hydrogen and oxygen evolution reactions

Clean and renewable energy is generally localized and intermittent. Thus, energy conversion and storage technologies are necessary to compensate for these shortcomings. Electrolytic water splitting presents a reliable and promising energy technology for producing high purity hydrogen (H2). Among the platinum metals, ruthenium (Ru) has gained significant attentions as it generally outperforms commercial catalysts in terms of activity at a more affordable price. Although great progress has been made in improving the catalytic activity of Ru-based catalysts, stability remains a major challenge hindering their practical applications. To this end, this review introduces the fundamentals of the stability over Ru-based catalysts for water splitting, including the reaction mechanisms of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), measurement methods and evaluation criteria, as well as deactivation mechanisms. Moreover, the up-to-date advances of representative strategies for improving HER and OER stability of Ru-based catalysts are further discussed with respect to specific design principles and underlying mechanisms. Ultimately, insights into the challenges and opportunities for Ru-based electrocatalysts are provided to promote the development of next-generation Ru-based catalysts with exceptional stability. This review aims at guiding the design and synthesis of superior catalysts, generating increased interest among researchers, and stimulating further advanced research.