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Vol. 18 (2026)

High Polarity Doping of CoFe Layered Hydroxides: Bifunctional and Corrosion-Resistant Anion Exchange Membrane Seawater Electrolyzers

https://doi.org/10.1007/s40820-026-02230-8
Anandhan Ayyappan Saj
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, South Korea
Sampath Prabhakaran
Division of AI Convergence Research, Korea Institute of Ceramic Engineering and Technology (KICET), Jinju 52851, Republic of Korea
Mohsin Rasool
University of Ulsan, Ulsan 44776, Republic of Korea
Kousik Bhunia
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, South Korea
Dongho Lee
University of Ulsan, Ulsan 44776, Republic of Korea
Hyunseok Ko
Division of AI Convergence Research, Korea Institute of Ceramic Engineering and Technology (KICET), Jinju 52851, Republic of Korea
Tukaram D. Dongale
Computational Electronics and Nanoscience Research Laboratory, School of Nanoscience and Biotechnology, Shivaji University, Kolhapur, Maharashtra 416004, India
Muthukumar Perumalsamy
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, South Korea
Arul Saravanan Raaju Sundhar
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, South Korea
Do Hwan Kim
Division of Science Education and Institute of Fusion Science, Department of Energy Storage/Conversion Engineering (BK21 FOUR), Jeonbuk National University, Jeonju, Jeonbuk 54896, Republic of Korea
Sang Jae Kim
Nanomaterials & System Lab, Major of Mechatronics Engineering, Faculty of Applied Energy System, Jeju National University, Jeju 63243, South Korea

Corresponding Author: Sang Jae Kim

kimsangj@jejunu.ac.kr

Nano-Micro Letters, Vol. 18 (2026), Article Number: 393

Abstract

Green hydrogen production through seawater electrolysis is a promising strategy, although challenges such as sluggish oxygen evolution reaction (OER) kinetics and chlorine (Cl−) corrosion hinder its practical applicability. A novel fluorine (F)-doped cobalt (Co) and iron (Fe) layered metal hydroxide (F-CoFe LMH-8) is developed as a robust bifunctional catalyst achieving 81.23 and 265.5 mV at 10 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Theoretical and experimental studies demonstrate that the F-doping modulates the electronic structure, effectively tuning Fe sites toward a high-spin configuration that optimizes binding energies and induces a chlorophobic effect that repel corrosive (Cl−) ions. Notably, the F-CoFe LMH-8( +|| −) bifunctional catalyst integrated anion exchange membrane water electrolyzer (AEMWE) exhibited outstanding performance for continuous H2 production, achieves a current density of 1.2 A cm−2 in 1 M KOH, 1.02 A cm−2 in 1 M KOH + 0.5 M NaCl, and 1 A cm−2 in 1 M KOH in seawater at 2.3 V. Furthermore, a long short-term memory-based machine learning model was employed to forecast and predict the stability of F-CoFe LMH-8. This approach provides a comprehensive pathway for heuristic design of durable, chlorophobic, and advanced electrocatalyst for seawater-based AEMWE and large-scale hydrogen production.


Highlights:
1 CoFe layered metal hydroxide (LMH) was synthesized via a MgO nanoparticle assisted method, fluorine (F) doping effectively modulated the electronic structure of CoFe LMH by selectively tuning Fe sites while preserving Co integrity, resulting in a high spin Fe configuration conducive to enhanced catalytic activity.
2 F-CoFe LMH-8 as a bifunctional catalyst , exhibiting strong hydrophilic and oxophilic behavior while effectively repelling chloride ions (chlorophobic) in seawater conditions.
3 F-CoFe LMH-8 (+||–) anion exchange membrane device delivered a current density of 1 A cm–2 at 2.3 V in seawater and maintained exceptional operational durability, exhibiting a degradation rate of only 0.15 μV h–1 over 500 h of continuous operation.

Keywords

Corrosion resistance F-doping H2 generation Seawater electrolysis Long short-term memory (LSTM)
Saj, Anandhan Ayyappan, Sampath Prabhakaran, Mohsin Rasool, Kousik Bhunia, Dongho Lee, Hyunseok Ko, Tukaram D. Dongale, Muthukumar Perumalsamy, Arul Saravanan Raaju Sundhar, Do Hwan Kim, and Sang Jae Kim. 2026. “High Polarity Doping of CoFe Layered Hydroxides: Bifunctional and Corrosion-Resistant Anion Exchange Membrane Seawater Electrolyzers”. Nano-Micro Letters 18 (June):393. https://doi.org/10.1007/s40820-026-02230-8.
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