Latest progresses of Ru-based catalysts for alkaline hydrogen oxidation reaction: From mechanism to application

The efficient energy conversion of hydroxide exchange membrane fuel cells (HEMFCs) is restrained by slow anodic hydrogen oxidation reaction (HOR) kinetics. Recently, Ru-based nanomaterials have emerged as the promising catalysts for alkaline HOR because of its much more attractive price advantage and reasonable intermediates binding ability, yet a comprehensive timely review on major achievements of Ru-based alkaline HOR catalysts is missing. Under the background, we aim to provide thorough knowledge of alkaline HOR on Ru-based catalysts, such as the developed mechanism viewpoints based on diverse experimental and advanced theoretical studies, the effective strategies to optimize both the catalytic activity and stability as well as the current progresses in the HEMFCs devices with Ru-anodes. Specifically, this review first covers three seemingly contradictive activity descriptors. In the following, the structure-activity relationship is shared to elucidate underlying performance improvement mechanisms. Then, the possible physical chemistry behind catalysts instability, including electrochemical degradations, oxides poisoning and CO susceptibility, is presented, and corresponding promising strategies for improving their stability are summarized. Next, the performance progresses of HEMFCs constructed by Ru-based anodic catalysts are provided. Finally, possible research directions for further enhancing Ru-based catalysts performance are suggested. Wherever is appropriate, our opinions are shared, hoping this review will serve as a guidance for the construction and development of efficient Ru-based catalysts for energy conversion.