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Vol. 18 (2026)

Decoding the Oxygen Reduction Reaction: Mechanistic Insights from Transition Metal Heterostructures

https://doi.org/10.1007/s40820-026-02197-6
Mingyu Sun
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Xiayan Zhang
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Jia Wang
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Jialu Liu
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Jinhai He
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Wanmiao Ge
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Shengwei Kong
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Guoqing Zhang
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Mai Gao
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Jingqiang Wang
College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, Inner Mongolia, People’s Republic of China
Zixu Sun
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Yaping Yan
Henan Engineering Technology Research Center for Fiber Preparation and Modification, Henan University of Engineering, Zhengzhou 451191, People’s Republic of China
Xinjian Shi
National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, School of Nanoscience and Materials Engineering, Henan University, Kaifeng 475004, People’s Republic of China
Yao Xiao
College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, People’s Republic of China

Corresponding Author: Yao Xiao

xiaoyao@wzu.edu.cn

Nano-Micro Letters, Vol. 18 (2026), Article Number: 351

Abstract

The oxygen reduction reaction (ORR) plays a central role in determining the efficiency and durability of a broad range of electrochemical energy conversion technologies, while its intrinsically slow kinetics and multistep reaction nature remain key challenges. Transition metal-based heterogeneous electrocatalysts, particularly those incorporating Fe, Mn, Co, Ni, and Cu, have been extensively investigated as ORR active systems owing to their earth abundance, diverse coordination environments, and tunable electronic structures. Recent studies show that ORR on these catalysts can diverge into two-electron and four-electron pathways from a common O2 reactant, with pathway selectivity governed by atomic-scale coordination and electronic effects. This review summarizes current understanding of ORR mechanisms on transition metal-based catalysts, with a focus on how atomic-scale structural features are related to reaction activity, selectivity, and stability under different electrolyte conditions. Representative applications in metal–air batteries, fuel cells, and electrochemical hydrogen peroxide production are also discussed to illustrate how mechanistic insights are reflected in practical electrochemical systems. By distilling shared mechanistic features across different systems, this review provides a coherent framework for understanding and guiding ORR catalyst design.


Highlights:
1 This review presents a unified mechanistic framework for oxygen reduction reaction catalysis across diverse transition metal systems (Fe, Mn, Co, Ni, Cu), linking electronic structure, coordination environment, and interfacial effects to pathway selectivity.
2 In situ/operando techniques and interfacial engineering are emphasized as critical tools for atomic-level active site probing and performance optimization.
3 A cross-scale design paradigm bridges molecular-level insights with practical applications in fuel cells, metal-air batteries, and H2O2 electrosynthesis.

Keywords

Oxygen reduction reaction Transition metal catalysts Heterogeneous electrocatalysis
Sun, Mingyu, Xiayan Zhang, Jia Wang, Jialu Liu, Jinhai He, Wanmiao Ge, Shengwei Kong, Guoqing Zhang, Mai Gao, Jingqiang Wang, Zixu Sun, Yaping Yan, Xinjian Shi, and Yao Xiao. 2026. “Decoding the Oxygen Reduction Reaction: Mechanistic Insights from Transition Metal Heterostructures”. Nano-Micro Letters 18 (May):351. https://doi.org/10.1007/s40820-026-02197-6.
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