In this work, we demonstrate that crystallographic site control of ruthenium in spinel Co₃O₄ is decisive for efficient and durable acidic oxygen evolution. Selective octahedral Ru substitution forms a cooperative Ruₒct–O–Coₒct active motif that activates the oxide-path mechanism, suppresses cobalt over-oxidation, and enables stable OER performance with only minimal Ru content. The optimized Oct-Ru₀.₁₃Co₂.₈₇O₄ catalyst therefore delivers low overpotential and long-term stability, highlighting site-specific engineering as a practical strategy for low-precious-metal PEM electrolysis anodes.

Key Insights

• Site-selective Ru doping in spinel Co₃O₄ enables direct comparison between octahedral (Co³⁺) and tetrahedral (Co²⁺) substitution.
• Octahedral Ru incorporation creates a synergistic Ruₒct–O–Coₒct dual-metal active center, enabling the oxide-path mechanism with a reduced reaction barrier.
• The optimized Oct-Ru₀.₁₃Co₂.₈₇O₄ achieves a low overpotential of 240 mV at 10 mA cm⁻² and remains stable for over 240 h in acidic electrolyte.
• Tetrahedral Ru substitution disrupts orbital overlap, leading to higher overpotential and rapid degradation.
• Electron transfer within the Ru–O–Co framework suppresses cobalt over-oxidation and dissolution, accounting for the enhanced durability.

Why It Matters

• Identifies octahedral Co³⁺ sites as the intrinsic active centers for acidic OER in spinel Co₃O₄.
• Demonstrates that high activity and durability can be achieved with only ~4 at% Ru, substantially reducing noble-metal demand.
• Establishes crystallographic site engineering as a general, scalable design principle for next-generation PEM water-electrolysis anodes.

Authors, Corresponding Authors, and Affiliations

Authors: Yumeng Wang, Yaling Zhang, Shiyao Chen, Yameng Fan, Jian Peng, Tofik Ahmed Shifa, Alberto Vomiero, Yaping Li*, Fengmei Wang*, and Xiaoming Sun* (corresponding authors).

Corresponding Authors (Emails):

• Yaping Li — liyp@mail.buct.edu.cn
• Fengmei Wang — wangfm@buct.edu.cn
• Xiaoming Sun — sunxm@mail.buct.edu.cn

Affiliations: State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing, China; School of Science, RMIT University, Melbourne, Australia; Eastern Institute for Advanced Study, Eastern Institute of Technology, Ningbo, China; Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Venice, Italy.

How to Cite

Wang, Y., Zhang, Y., Chen, S. et al. Site-selective Ru doping in spinel Co3O4 unlocks dual-site synergy for acidic water electrolysis. Catal 2, 4 (2026). https://doi.org/10.1007/s44422-026-00018-w