Synergistic Oxygen Vacancy and Ru–N Coordination in RuO₂@NCC for Enhanced Acidic Oxygen Evolution Reaction

Abstract

Developing efficient and durable electrocatalysts for acidic oxygen evolution reaction (OER) is pivotal for advancing proton exchange membrane water electrolysis (PEMWEs), yet balancing activity and stability remains a formidable challenge. Herein, we propose a dual-engineering strategy to stabilize Ru-based catalysts by synergizing the oxygen vacancy site-synergized mechanism-lattice oxygen mechanism (OVSM-LOM) with Ru–N bond stabilization. The engineered RuO₂@NCC catalyst exhibits exceptional OER performance in 0.5 M H₂SO₄, achieving an ultralow overpotential of 215 mV at 10 mA cm^–2 and prolonged stability for over 327 h. The catalyst delivers 300 h of continuous operation at 1 A cm^–2, with a negligible degradation rate of only 0.067 mV h^–1, further demonstrating its potential for practical application. Oxygen vacancies unlock the OVSM-LOM pathway, bypassing the sluggish adsorbate evolution mechanism (AEM) and accelerating reaction kinetics, while the Ru–N bonds suppress Ru dissolution by anchoring low-valent Ru centers. Quasi-in situ X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and isotopic labeling experiments confirm the lattice oxygen participation with *O formation as the rate-determining step. The Ru–N bonds reinforce the structural integrity by stabilizing low-valent Ru centers and inhibiting overoxidation. Theoretical calculations further verify that the synergistic interaction between O_Vs and Ru–O(N) active sites optimizes the Ru d-band center and stabilizes intermediates, while Ru–N coordination enhances structural integrity. This study establishes a novel paradigm for designing robust acidic OER catalysts through defect and coordination engineering, bridging the gap between activity and stability for sustainable energy technologies.

Keywords

OVSM-LOM / oxygen evolution reaction / oxygen vacancy / Ru–N / XAFS

References

[1] L. An, C. Wei, M. Lu, et al., “Recent Development of Oxygen Evolution Electrocatalysts in Acidic Environment,” Advanced Materials 33 (2021): e2006328.

[2] N. Han, W. Zhang, W. Guo, et al., “Designing Oxide Catalysts for Oxygen Electrocatalysis: Insights From Mechanism to Application,” Nano-Micro Letters 15 (2023): 185–218.

[3] R. Ram, L. Xia, H. Benzidi, et al., “Water-Hydroxide Trapping in Cobalt Tungstate for Proton Exchange Membrane Water Electrolysis,” Science 384 (2024): 1373–1380.

[4] L. Liang, T. Zhou, P. Tsiakaras, and P. Shen, “Anion Exchange Membrane Water Electrolysis Enhanced by Reverse Electron Redistribution Caused by La Introduction,” Applied Catalysis B: Environment and Energy 373 (2025): 125332.

[5] C. He, L. Yang, J. Wang, et al., “Research Progress on Electronic and Active Site Engineering of Cobalt-Based Electrocatalysts for Oxygen Evolution Reaction,” Carbon Energy 6 (2024): e573.

[6] J. Zhu, Y. Guo, F. Liu, et al., “Regulative Electronic States Around Ruthenium/Ruthenium Disulphide Heterointerfaces for Efficient Water Splitting in Acidic Media,” Angewandte Chemie International Edition 60 (2021): 12328–12334.

[7] Y. Wen, P. Chen, L. Wang, et al., “Stabilizing Highly Active Ru Sites by Suppressing Lattice Oxygen Participation in Acidic Water Oxidation,” Journal of the American Chemical Society 143 (2021): 6482–6490.

[8] E. Pastor, Z. Lian, L. Xia, et al., “Complementary Probes for the Electrochemical Interface,” Nature Reviews Chemistry 8 (2024): 159–178.

[9] G. Gao, Z. Sun, X. Chen, et al., “Recent Advances in Ru/Ir-Based Electrocatalysts for Acidic Oxygen Evolution Reaction,” Applied Catalysis, B: Environmental 343 (2024): 123584.

[10] M. Kim, J. Park, M. Wang, et al., “Role of Surface Steps in Activation of Surface Oxygen Sites on Ir Nanocrystals for Oxygen Evolution Reaction in Acidic Media,” Applied Catalysis, B: Environmental 302 (2022): 120834.

[11] J. Li, “Oxygen Evolution Reaction in Energy Conversion and Storage: Design Strategies Under and Beyond the Energy Scaling Relationship,” Nano-Micro Letters 14 (2022): 112–144.

[12] X. Liu, Z. He, M. Ajmal, et al., “Recent Advances in the Comprehension and Regulation of Lattice Oxygen Oxidation Mechanism in Oxygen Evolution Reaction,” Transactions of Tianjin University 29 (2023): 247–253.

[13] Z. Jia, Y. Yuan, Y. Zhang, et al., “Optimizing 3d Spin Polarization of COOOH by In Situ Mo Doping for Efficient Oxygen Evolution Reaction,” Carbon Energy 6 (2023): e418.

[14] H. Jin, S. Choi, G. J. Bang, et al., “Safeguarding the RuO₂ Phase Against Lattice Oxygen Oxidation During Acidic Water Electrooxidation,” Energy & Environmental Science 15 (2022): 1119–1130.

[15] J. Song, C. Wei, Z. F. Huang, et al., “A Review on Fundamentals for Designing Oxygen Evolution Electrocatalysts,” Chemical Society Reviews 49 (2020): 2196–2214.

[16] M. Sohail, W. Lv, and Z. Mei, “Recent Progress in Ruthenium-Based Electrocatalysts for Water Oxidation Under Acidic Condition,” ACS Sustainable Chemistry & Engineering 11 (2023): 17564–17594.

[17] H. Zhang, D. Guan, Y. Gu, et al., “Tuning Synergy Between Nickel and Iron in Ruddlesden–Popper Perovskites Through Controllable Crystal Dimensionalities Towards Enhanced Oxygen-Evolving Activity and Stability,” Carbon Energy 6 (2024): e465.

[18] N. Zhang and Y. Chai, “Lattice Oxygen Redox Chemistry in Solid-State Electrocatalysts for Water Oxidation,” Energy & Environmental Science 14 (2021): 4647–4671.

[19] X. Li, C. Deng, Y. Kong, et al., “Unlocking the Transition of Electrochemical Water Oxidation Mechanism Induced by Heteroatom Doping,” Angewandte Chemie International Edition 62 (2023): e202309732.

[20] C. F. Dickens and J. K. Nørskov, “A Theoretical Investigation Into the Role of Surface Defects for Oxygen Evolution on RuO₂,” Journal of Physical Chemistry C 121 (2017): 18516–18524.

[21] A. Zagalskaya and V. Alexandrov, “Role of Defects in the Interplay Between Adsorbate Evolving and Lattice Oxygen Mechanisms of the Oxygen Evolution Reaction in RuO₂ and IrO₂,” ACS Catalysis 10 (2020): 3650–3657.

[22] Y. Tian, S. Wang, E. Velasco, et al., “A Co-Doped Nanorod-Like RuO(2) Electrocatalyst With Abundant Oxygen Vacancies for Acidic Water Oxidation,” iScience 23 (2020): 100756.

[23] Y. Li, Y. Wang, J. Lu, B. Yang, X. San, and Z. S. Wu, “2D Intrinsically Defective RuO₂/Graphene Heterostructures as All-pH Efficient Oxygen Evolving Electrocatalysts With Unprecedented Activity,” Nano Energy 78 (2020): 105185.

[24] J. Zhang, D. Yang, Z. Yang, and L. Wang, “Utilizing Cationic Vacancy Defects to Switch Oxygen Evolution Mechanisms on Atomically Dispersed Ru for Enhanced Acidic Catalytic Performance,” Applied Catalysis B: Environment and Energy 364 (2025): 124845.

[25] S. Hao, M. Liu, J. Pan, et al., “Dopants Fixation of Ruthenium for Boosting Acidic Oxygen Evolution Stability and Activity,” Nature Communications 11 (2020): 5368–5379.

[26] T. Xia, C. Liu, Y. Lu, et al., “Regulating Ru-Based Double Perovskite Against Lattice Oxygen Oxidation by Incorporating Ir for Efficient and Stable Acidic Oxygen Evolution Reaction,” Applied Surface Science 605 (2022): 154727.

[27] X. Long, B. Zhao, Q. Zhao, et al., “Ru-RuO₂ Nano-Heterostructures Stabilized by the Sacrificing Oxidation Strategy of Mn₃O₄ Substrate for Boosting Acidic Oxygen Evolution Reaction,” Applied Catalysis, B: Environmental 343 (2024): 123559.

[28] L. Zhang, H. Jang, H. Liu, et al., “Sodium-Decorated Amorphous/Crystalline RuO(2) With Rich Oxygen Vacancies: A Robust pH-Universal Oxygen Evolution Electrocatalyst,” Angewandte Chemie International Edition 60 (2021): 18821–18829.

[29] J. Kang, X. Qiu, Q. Hu, et al., “Valence Oscillation and Dynamic Active Sites in Monolayer Nico Hydroxides for Water Oxidation,” Nature Catalysis 4 (2021): 1050–1058.

[30] Z.-F. Huang, J. Song, Y. Du, et al., “Chemical and Structural Origin of Lattice Oxygen Oxidation in Co–Zn Oxyhydroxide Oxygen Evolution Electrocatalysts,” Nature Energy 4 (2019): 329–338.

[31] N. Yao, H. Jia, J. Zhu, et al., “Atomically Dispersed Ru Oxide Catalyst With Lattice Oxygen Participation for Efficient Acidic Water Oxidation,” Chem 9 (2023): 1882–1896.

[32] L. Zhang, W. Li, S. Ren, et al., “Manipulating d-Band Center of Ru Sites in Branched RuO₂ Nanofibers Enables Significantly Enhanced Alkaline Overall Water Splitting Performance,” Advanced Energy Materials 15 (2024): 202403136.

[33] P. Ma, H. Cao, Q. Hao, et al., “Neighbouring Synergy in High-Density Single Ir Atoms on CoGaOOH for Efficient Alkaline Electrocatalytic Oxygen Evolution,” Angewandte Chemie International Edition 63 (2024): e202404418.

[34] H. Yan, Z. Jiang, B. Deng, Y. Wang, and Z. Jiang, “Ultrathin Carbon Coating and Defect Engineering Promote RuO₂ as an Efficient Catalyst for Acidic Oxygen Evolution Reaction With Super-High Durability,” Advanced Energy Materials 13 (2023): 202300152.

[35] M. Luo, J. Cai, J. Zou, Z. Jiang, G. Wang, and X. Kang, “Promoted Alkaline Hydrogen Evolution by an N-Doped Pt–Ru Single Atom Alloy,” Journal of Materials Chemistry A 9 (2021): 14941–14947.

[36] J. R. McBride, K. C. Hass, B. D. Poindexter, and W. H. Weber, “Raman and X-Ray Studies of Ce_1−xRe_xO_2−y, Where Re=La, Pr, Nd, Eu, Gd, and Tb,” Journal of Applied Physics 76 (1994): 2435–2441.

[37] J. Jiang, F. Sun, S. Zhou, et al., “Atomic-Level Insight Into Super-Efficient Electrocatalytic Oxygen Evolution on Iron and Vanadium Co-Doped Nickel (Oxy)Hydroxide,” Nature Communications 9 (2018): 2885–2897.

[38] G. Assat and J.-M. Tarascon, “Fundamental Understanding and Practical Challenges of Anionic Redox Activity in Li-Ion Batteries,” Nature Energy 3 (2018): 373–386.

[39] M. Zhang, M. de Respinis, and H. Frei, “Time-Resolved Observations of Water Oxidation Intermediates on a Cobalt Oxide Nanoparticle Catalyst,” Nature Chemistry 6 (2014): 362–367.

[40] Y. Lin, L. Yu, L. Tang, F. Song, R. Schlögl, and S. Heumann, “In Situ Identification and Time-Resolved Observation of the Interfacial State and Reactive Intermediates on a Cobalt Oxide Nanocatalyst for the Oxygen Evolution Reaction,” ACS Catalysis 12 (2022): 5345–5355.

[41] M. Qi, X. Du, X. Shi, et al., “Single-Atom Ru-Triggered Lattice Oxygen Redox Mechanism for Enhanced Acidic Water Oxidation,” Journal of the American Chemical Society 147 (2025): 18295–18306.

[42] H. Liu, Z. Zhang, J. Fang, et al., “Eliminating Over-Oxidation of Ruthenium Oxides by Niobium for Highly Stable Electrocatalytic Oxygen Evolution in Acidic Media,” Joule 7 (2023): 558–573.

[43] G. Kresse and J. Hafner, “Ab Initio Molecular-Dynamics Simulation of the Liquid-Metal-Amorphous-Semiconductor Transition in Germanium,” Physical Review B 49 (1994): 14251–14269.

[44] G. Kresse and J. Furthmüller, “Efficiency of Ab-Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set,” Computational Materials Science 6 (1996): 15–50.

RIGHTS & PERMISSIONS

2025 The Author(s). Carbon Energy published by Wenzhou University and John Wiley & Sons Australia, Ltd.