Recent advance of Ru-based bifunctional electrocatalysts for Zn–air batteries

Zinc-air batteries (ZABs) hold significant promise for next-generation energy storage due to their high theoretical energy density, inherent safety, and low cost. Nevertheless, commercialization is impeded by sluggish oxygen redox kinetics at air cathodes, which causes substantial charge-discharge polarization and low round-trip efficiency. While existing bifunctional catalysts struggle to balance activity and stability, Ru-based catalysts have emerged as a transformative solution by optimizing electronic structures to facilitate oxygen intermediate adsorption/desorption. This review examines recent advances in Ru-based catalysts, categorizing strategies into composites, compounds, and single-atom supported catalysts. We analyze the roles of compositing, doping, and support engineering in enhancing activity-stability synergy, extracting design principles for each category. Furthermore, we outline key research directions including ultralow Ru loading, multi-site synergy, and corrosion mitigation. By mapping cost-activity-stability relationships and identifying development pathways, this work provides a roadmap toward industrial ZAB deployment for Ru-based catalysts.