Mechanistic Understanding of Curvature Effects on ORR/OER Activity in Single‐Atom Catalysts From Atomic‐Scale Perspective

Why It Matters

The curvature‑driven orbital engineering provides a new design lever for high‑performance single‑atom catalysts, potentially accelerating metal‑air battery commercialization and reducing dependence on scarce precious metals.

Key Takeaways

• Curvature alters d-orbital energy ordering in Cu-doped BNNTs.
• Inverted dz2 level boosts ORR/OER catalytic activity.
• Strain shifts d-band center, but curvature has larger effect.
• Scaling relationships broken, enabling higher efficiency.
• BN nanotubes viable electrocatalysts per cohesive energy analysis.

Pulse Analysis

Oxygen reduction and evolution reactions remain the kinetic bottlenecks in metal‑air batteries, prompting intense research into atom‑efficient electrocatalysts. Single‑atom catalysts anchored on two‑dimensional supports have shown promise, yet their activity is often constrained by linear scaling relationships between reaction intermediates. Introducing curvature—by rolling a monolayer into a nanotube—adds a geometric degree of freedom that can reshape electronic structures without altering composition, offering a fresh pathway to break those limits.

In the recent computational study, copper atoms were substituted into boron nitride nanotubes of varying diameters, and density‑functional theory revealed that curvature redistributes the d‑orbital sub‑levels. The dz2 orbital, typically highest in energy, flips to the lowest, while the dxy and dx2‑y2 degeneracy lifts. This inversion changes adsorption strengths for *OH, *O, and *OOH intermediates, effectively decoupling the otherwise linear energy correlations. Tensile strain also modulates the d‑band center, but its impact is modest compared with the profound orbital reordering induced by curvature, highlighting curvature as the dominant tuning knob.

The implications extend beyond academic curiosity. By leveraging curvature, catalyst designers can engineer single‑atom sites that achieve optimal binding energies without resorting to expensive noble metals. This approach could accelerate the development of high‑energy‑density metal‑air batteries for electric vehicles and grid storage. Moreover, the methodology—combining curvature engineering with strain and dopant selection—offers a versatile toolkit for next‑generation electrocatalyst discovery across a range of energy conversion technologies.