Revisiting necessity of high-entropy electrocatalysts

Comment https://doi.org/10.1038/s41467-026-73502-5 Revisiting necessity of high-entropy electrocatalysts 1234567890():,; 1234567890():,; Jiali Wang, Feng-Ze Tian & Hao Ming Chen High-entropy alloys are often presumed stable and intrinsically beneficial for electrocatalysis. This Comment argues that in situ structural evolution can diminish configurational entropy, necessitating rigorous identification of active phases under operando conditions before attributing catalytic performance to high-entropy effects. High-entropy alloys (HEAs) have recently emerged as compelling candidates in the field of electrocatalysis owing to their ability to form compositionally complex solid solutions that integrate a diverse array of surface active sites within a single-phase structure1–3. Thermodynamically, their high configurational entropy suppresses phase segregation, and kinetically, sluggish diffusion effect confers kinetic stability, leading to expectations of superior physical and chemical stability over conventional alloys4. However, experimental studies under electrocatalytic conditions have revealed critical concerns5,6. During reactions such as the oxygen evolution reaction (OER) at anodic potentials or hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR) in cathodic environments, HEAs have been shown to undergo surface reconstructions7–12. These transformations raise a fundamental question: can the high-entropy configuration still be regarded as the catalytically active phase if an HEA undergoes significant structural or compositional changes during reaction? Moreover, once the in situ-formed active structure is a simpler phase, it is essential to consider whether comparable performance could be achieved using a conventional catalyst. This knowledge gap is particularly critical, as such transformations are intimately linked to catalytic properties and mechanistic insights. This Comment calls for a more critical evaluation of HEA design in electrocatalysis, with particular emphasis on how structural and compositional changes may compromise the intended high-entropy state. By clarifying the conceptual foundations of high-entropy catalyst design and outlining plausible transformation pathways, we aim to promote more rigorous investigation of HEAs as functional and reliable electrocatalysts. Entropy-driven principles in electrocatalyst design Unique surface ensembles. Unlike monometallic/binary alloys, HEAs create a vast array of local atomic configurations on a single catalyst surface13. This inherent structural heterogeneity results in a wide distribution of adsorption energies for reaction intermediates rather than a narrow or singular binding energy profile. Theoretically, such diversity enhances the likelihood of encountering surface sites with near-optimal adsorption energies for specific intermediates3. nature communications Check for updates Consequently, HEAs have the potential to circumvent the limitations imposed by conventional volcano-type relationships by spanning a broader region of the activity-binding energy curve. Breaking scaling relations. Another compelling feature of HEAs is their potential to overcome the limitations imposed by linear scaling relationships between adsorbed reaction intermediates. The distinct chemical roles of neighboring elements can create synergistic effects, enabling the concerted tuning of catalytic activity beyond the reach of conventional alloys. Furthermore, the multifunctional nature of HEA surfaces provides the possibility for versatile active sites to participate in discrete stages of a reaction pathway. Stability expectations. HEAs are also widely regarded as intrinsically stable materials. At elevated temperatures, the high configurational entropy favors the formation of a single-phase, chemically disordered structure, while at lower temperatures, sluggish atomic diffusion provides kinetic barriers that suppress phase separation and elemental migration3. These characteristics have led to the expectation that HEAs are inherently resistant to degradation pathways commonly observed in conventional alloys during electrocatalysis. Building on these proposed advantages, HEAs have been actively investigated in electrocatalytic applications, benefiting from so-called “synergistic effects” or the “high-entropy effect”14. However, a critical assumption underlying numerous reports is that the HEA maintains its single-phase, multi-elemental configuration during reactions. The following sections critically assess the validity of this assumption under practical electrochemical conditions and explore potential transformation pathways that may undermine the fundamental integrity of HEA electrocatalysts. Traits that may lead to entropy loss Dealloying and leaching. Electrocatalytic operation can trigger irreversible surface degradation through dealloying and leaching, particularly during anodic reactions like OER, which directly dismantle the multi-elemental complexity of HEAs. High anodic potentials and reactive oxygen species drive selective dissolution of the most electrochemically vulnerable metals, as predicted by Pourbaix diagrams, yielding a structurally and compositionally simplified surface oxide with reduced configurational entropy (Fig. 1). For instance, IrFeCoNiCu HEA nanoparticles under acidic OER conditions leach 3d transition metals, forming an Ir-enriched surface oxide shell15, questioning the original high-entropy contribution despite enhanced stability. Similarly, the Cantor alloy (CoCrFeNiMn) in alkaline conditions loses Cr and Mn16, resulting in a Ni/Fe/Co oxyhydroxide surface that reduces the HEA to a conventional ternary oxide. Although such restructuring may occasionally improve activity (e.g., exposing active IrOx species), it often disrupts synergistic interactions or causes irreversible material loss, undermining the intended benefits of high‑entropy design. (2026)17:5278 | 1 Comment Configurational entropy (ΔSmix) ΔSmix = –R∑ 1.61R 1.39R 1.10R 0.69R Surface reconstruction Dealloying/ leaching Alloying/atomic redistribution Chemical reactions with reactants Fig. 1 | Schematic of potential pathways for entropy loss in HEAs under electrocatalytic conditions. The thermodynamic driving force for these transformations is underpinned by the change in configurational entropy (ΔSmix). For a multicomponent alloy system (represented by colored spheres) with an equimolar composition, ΔSmix can be simplified as Rln(n), where R is the molar gas constant, and n is the number of elements. The ideal ΔSmix values for binary, ternary, quaternary and quinary systems are calculated as 0.69 R, 1.10 R, 1.39 R, and 1.61 R, respectively. The arrows depict representative degradation routes from a highentropy solid solution towards lower-entropy states. Surface reconstruction, oxidation, and formation of new phases. Under anodic potentials, 3d transition metals in HEAs readily form oxyhydroxide layers (Fig. 1), widel (...truncated)