Key Takeaways & Executive Findings
- •• A self-constructed IrO2/IrTaOx bi-layer nanostructure, derived from an Ir–Ta metallic glass, achieves high-efficiency acidic OER with a mass activity of 1.06 A mgIr−1 at 300 mV overpotential, outperforming commercial Ir/C and IrO2 by 13.6 and 31.2 times, respectively. • The electronic interaction between Ir and Ta modulates the coordination environment of active Ir sites, preventing rapid oxidation to high-valence states and suppressing lattice oxygen participation, thereby enhancing both activity and stability. • The underlying amorphous IrTaOx layer dynamically replenishes depleted surface Ir sites via inward crystallization and selective dissolution, ensuring long-term durability under industrial-relevant current densities in acid. • This work provides a novel strategy for designing durable, low-Ir OER catalysts for PEM water electrolysis, addressing critical challenges of high noble metal loading and inadequate stability.
Abstract
Proton exchange membrane (PEM) water electrolysis presents considerable advantages in green hydrogen production. Nevertheless, oxygen evolution reaction (OER) catalysts in PEM water electrolysis currently encounter several pressing challenges, including high noble metal loading, low mass activity, and inadequate durability, which impede their practical application and commercialization. Here we report a self-constructed layered catalyst for acidic OER by directly using an Ir–Ta-based metallic glass as the matrix, featuring a nanoporous IrO2 surface formed in situ on the amorphous IrTaOx nanostructure during OER. This distinctive architecture significantly enhances the accessibility and utilization of Ir, achieving a high mass activity of 1.06 A mgIr−1 at a 300 mV overpotential, 13.6 and 31.2 times greater than commercial Ir/C and IrO2, respectively. The catalyst also exhibits superb stability under industrial-relevant current densities in acid, indicating its potential for practical uses. Our analyses reveal that the coordinated nature of the surface-active Ir species is effectively modulated through electronic interaction between Ir and Ta, preventing them from rapidly evolving into high valence states and suppressing the lattice oxygen participation. Furthermore, the underlying IrTaOx dynamically replenishes the depletion of surface-active sites through inward crystallization and selective dissolution, thereby ensuring the catalyst’s long-term durability.
1. Introduction
Green hydrogen produced through water electrolysis is considered a promising energy carrier for balancing the intermittency of renewable energy sources [1, 2]. Among various water electrolysis technologies, proton-exchange membrane (PEM) water electrolysis has recently garnered significant research interest due to its advantages of high current density, low resistance, and super gas purity [3–7], outperforming the dominant alkaline water electrolysis. However, the large-scale implementation of PEM water electrolysis is impeded by the scarcity of active and stable anodic oxygen evolution reaction (OER) electrocatalysts [8, 9]. Most existing OER catalysts are impaired by sluggish reaction kinetics in acidic environments and suffer from severe degradation under harsh corrosive and oxidative conditions [10–13].
To date, precious iridium (Ir)-based materials, such as IrO2, remain the only known practical OER catalysts [14–17]. Nevertheless, they still face challenges of low mass activity and thermodynamic instability during prolonged and high-current-density acidic oxygen evolution [18, 19]. Therefore, to enhance the competitiveness of PEM water electrolysis, it is highly desirable, yet remains a challenge, to develop novel acidic OER electrocatalysts with higher activity, long-term stability, and lower Ir content.
Recently, alloying strategies have emerged as a promising approach to enhancing acidic OER performance and reducing the content of Ir [20–22]. Various studies indicate that alloying or doping high-valence metals with strong electronegativity and high chemical stability, such as Ta, W, and Nb, can effectively enhance the OER activity and stability of Ir-based catalysts. For instance, synthesized compounds such as Ir0.1Ta0.9O2.45 [23], TaxTmyIr1−x−yO2−δ [24], Ir-W@Ir-WO3−x [25], and Ir/Nb2O5−x [26] demonstrate superior OER activity and stability compared to basic IrO2 nanoparticles in acid media due to the electronic structure manipulation induced by high-valence metals, which can effectively optimize the Ir–O bonding strength and thereby enhancing the OER electrocatalysis. However, the stability of these nanocatalysts is still limited under a low current density (e.g., 10 mA cm−2).
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Qi Guo, Rui Li, Yanan Zhang, Qiqin Zhang, Yi He, Zhibin Li, Weihong Liu, Xiongjun Liu, Zhaoping Lu (2025). Durable Acidic Oxygen Evolution Via Self-Construction of Iridium Oxide/Iridium-Tantalum Oxide Bi-Layer Nanostructure with Dynamic Replenishment of Active Sites. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01680-w
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Frequently Asked Questions
What is the main innovation of this research?
The research introduces a self-constructed catalyst with an in situ formed IrO2/IrTaOx bi-layer nanostructure derived from an Ir–Ta metallic glass, which significantly enhances acidic oxygen evolution reaction (OER) activity and durability while reducing iridium content.
How does the catalyst achieve high mass activity?
The nanoporous IrO2 surface formed in situ on the amorphous IrTaOx nanostructure increases the accessibility and utilization of iridium, achieving a mass activity of 1.06 A mgIr−1 at 300 mV overpotential, which is 13.6 and 31.2 times higher than commercial Ir/C and IrO2, respectively.
What is the role of tantalum in the catalyst?
Tantalum modulates the electronic structure of iridium through electronic interaction, preventing rapid oxidation to high-valence states and suppressing lattice oxygen participation, thereby enhancing both activity and stability.
How does the catalyst maintain long-term durability?
The underlying amorphous IrTaOx layer dynamically replenishes depleted surface iridium sites through inward crystallization and selective dissolution, ensuring sustained catalytic activity under industrial-relevant current densities in acid.
What are the potential applications of this catalyst?
This catalyst is designed for proton exchange membrane (PEM) water electrolysis, offering a promising solution for efficient and durable green hydrogen production with reduced noble metal loading.
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