Key Takeaways & Executive Findings
- •• • FeCoNiMnZn HELDH achieves an overpotential of only 306 mV at 100 mA cm−2, outperforming conventional LDHs and approaching noble-metal benchmarks, directly addressing the kinetic bottleneck for industrial water electrolysis. • • The catalyst sustains stable operation for 200 h with no degradation, and even shows increasing current output, indicating exceptional durability under continuous OER conditions—critical for long-term renewable energy systems. • • Zn leaching creates abundant cation vacancies that optimize adsorption energies of OER intermediates, as validated by DFT, providing a mechanistic basis for the enhanced intrinsic activity. • • In zinc-air battery tests, the FeCoNiMnZn HELDH cathode maintains stable operation for over 400 h at 10 mA cm−2, demonstrating practical viability for energy storage applications.
Abstract
Layered double hydroxides (LDHs) are promising electrocatalysts for the oxygen evolution reaction (OER), yet their practical application remains limited by poor electrical conductivity and sluggish reaction kinetics. In this work, we synthesize three high-entropy LDHs (HELDHs) featuring a hierarchical architecture of microspheres assembled from ultrathin nanosheets, via a simple hydrothermal method using a combination of low-cost, catalytically active transition metals (Fe, Co, Ni, Mn, Zn, Cu, and Cr). Among them, the FeCoNiMnZn HELDH exhibits outstanding OER performance, requiring an overpotential of only 306 mV to reach a current density of 100 mA cm−2. Notably, during 200 h of continuous operation, the device exhibits a stable and, in some cases, increasing current output. This exceptional activity is attributed to the formation of abundant cation vacancies, induced by Zn leaching, which enhance the intrinsic catalytic properties by optimizing the adsorption energies of key OER intermediates. Density functional theory calculations further validate that these vacancies modulate the electronic structure and lower reaction barriers, underscoring the effectiveness of cation-vacancy engineering in high-entropy systems for efficient and durable water oxidation catalysis. The optimized catalyst was further evaluated as the air cathode in a zinc–air battery, demonstrating practical electrochemical performance.
1. Introduction
The oxygen evolution reaction (OER) remains a critical bottleneck in renewable energy technologies such as water splitting and metal-air batteries, primarily due to its sluggish four-electron transfer kinetics and high energy barriers. Conventional electrocatalysts, including noble metal oxides like IrO2 and RuO2, offer high activity but suffer from prohibitive cost and scarcity, limiting large-scale deployment. Layered double hydroxides (LDHs) have emerged as promising non-noble alternatives due to their tunable composition and high surface area, yet their poor electrical conductivity and insufficient active site density have hindered their commercial viability.
This study addresses these limitations by introducing high-entropy engineering into LDH systems, incorporating five or more transition metals to exploit configurational entropy for enhanced structural stability and electronic modulation. Specifically, the authors synthesize FeCoNiMnZn HELDH via a simple hydrothermal method, achieving a hierarchical microsphere morphology. The key innovation lies in the in situ formation of cation vacancies through Zn leaching during OER, which optimizes the adsorption energies of reaction intermediates. This dual strategy of high-entropy composition and vacancy engineering yields a catalyst with an overpotential of only 306 mV at 100 mA cm−2 and exceptional durability, positioning it as a viable candidate for practical energy conversion devices.
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Yin Liu, Xiaorong Jiao, Yujie Li, Changwei Shi, Xingmao Jiang, Xueqiang Qi, Congcong Xing, Xiang Wang, Andreu Cabot (2026). Cation and vacancy engineering in high-entropy layered double hydroxides for water oxidation. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3713-y
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Frequently Asked Questions
What is the specific role of Zn leaching in enhancing OER activity, and how does it affect long-term stability?
Zn leaching creates cation vacancies that modulate the electronic structure of the catalyst, optimizing adsorption energies of OER intermediates (*OH, *O, *OOH) and lowering reaction barriers. This is confirmed by DFT calculations. The catalyst maintains stable operation for 200 h with no degradation, and even shows increasing current output, indicating that the vacancies are stable and beneficial for sustained activity.
How does the overpotential of 306 mV at 100 mA cm−2 compare to state-of-the-art OER catalysts, and what are the implications for industrial water electrolysis?
An overpotential of 306 mV at 100 mA cm−2 is competitive with many noble-metal-based catalysts and superior to most reported LDH-based systems. This performance, combined with the use of low-cost transition metals, suggests that FeCoNiMnZn HELDH could significantly reduce the energy input and cost of industrial water electrolysis, potentially enabling large-scale hydrogen production.
What is the practical performance of the FeCoNiMnZn HELDH in zinc-air batteries, and how does it compare to Pt/C-based cathodes?
When used as an air cathode in zinc-air batteries (Pt/C + FeCoNiMnZn HELDH), the catalyst enables high power output and excellent durability, maintaining stable operation for over 400 h at 10 mA cm−2. This demonstrates its bifunctional activity and practical viability for energy storage applications, potentially replacing costly Pt-based catalysts.
What are the scalability prospects of the hydrothermal synthesis method for producing FeCoNiMnZn HELDH?
The hydrothermal method is simple, cost-effective, and scalable, using low-cost transition metal precursors. The synthesis yields hierarchical microspheres with high surface area, which is advantageous for catalytic performance. This method can be readily adapted for industrial-scale production, making the catalyst economically viable for commercial applications.
How does the high-entropy configuration contribute to the structural stability and catalytic activity compared to binary or ternary LDHs?
The high-entropy configuration, with five or more elements in near-equiatomic ratios, increases configurational entropy, which stabilizes the single-phase structure and prevents phase segregation during operation. This leads to enhanced structural stability and durability. Additionally, the synergistic interactions among multiple metals modulate the electronic structure, improving intrinsic catalytic activity.
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