Curvature-directed electrochemical reactivity on topological carbon

Abstract

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  High-curvature pentagon carbon (HCPC) is built via an ionic nano-autoclave strategy
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  Curvature-enhanced local electric fields accelerate OH⁻ desorption
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  HCPC achieves ultrahigh ORR activity and specific capacitance in alkaline media
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  Atomic curvature engineering unlocks intrinsic reactivity of topological-defect carbon

Topological defects profoundly influence the electronic structure and electrochemical behaviors of carbon materials. While previous studies have primarily focused on increasing defect density, the decisive role of the geometric microenvironment surrounding defect sites remains largely unexplored. In this work, we systematically reveal that a high geometric curvature can fundamentally unlock the intrinsic reactivity of pentagonal carbon. By utilizing an “ionic nano-autoclave” strategy, we synthesize a nanobubble-like carbon framework with an ultralow curvature radius of 1.47 nm, which effectively stabilizes the highly strained pentagonal defects. We demonstrate, for the first time, that curvature-induced electronic redistribution and intensified local electric fields of pentagonal defects synergistically accelerate the oxygen reduction kinetics by promoting OH⁻ desorption and optimizing intermediate adsorption. More importantly, this work establishes geometric curvature as a new structure descriptor beyond conventional defect-density engineering, offering direct insights into the intrinsic activity origin of topological carbon. This study represents an important step toward understanding the curvature-regulated electrochemical behaviors in carbon systems and provides a new paradigm for designing advanced metal-free carbon catalysts for sustainable energy conversion and storage technologies in the future.

Topological carbon profoundly influences the electrochemical behavior of carbon frameworks. However, prevailing research primarily focuses on increasing topological defect densities, whereas the influence of geometric microenvironments, particularly curvature, on intrinsic activity remains unexplored. Here, we synthesize nanobubble-like high-curvature pentagon carbon (HCPC) with ultralow curvature radius of 1.47 nm via a molten salt-assisted strategy that stabilizes highly strained pentagonal motifs. HCPC exhibits a half-wave potential of 0.80 V for oxygen reduction and a specific capacitance of 250.4 F g⁻¹, outperforming low-curvature counterpart carbon (LCCC). Crucially, the intrinsic activity of pentagonal sites in HCPC is 2.48 and 1.61 times higher than that of LCCC at 0.80 and 0.85 V, respectively, indicating that high curvature fundamentally transforms site reactivity. Futher analyses unveil that curvature-induced electronic redistribution and intensified local electric fields synergistically facilitate rapid OH⁻ desorption, preventing site poisoning and accelerating reaction kinetics. The topological-defect curvature engineering provides a method for designing high-performance catalysts.

Topological carbon profoundly influences the electrochemical behavior of carbon frameworks. However, prevailing research primarily focuses on increasing topological defect densities, whereas the influence of geometric microenvironments, particularly curvature, on intrinsic activity remains unexplored. Here, we synthesize nanobubble-like high-curvature pentagon carbon (HCPC) with ultralow curvature radius of 1.47 nm via a molten salt-assisted strategy that stabilizes highly strained pentagonal motifs. HCPC exhibits a half-wave potential of 0.80 V for oxygen reduction and a specific capacitance of 250.4 F g⁻¹, outperforming low-curvature counterpart carbon (LCCC). Crucially, the intrinsic activity of pentagonal sites in HCPC is 2.48 and 1.61 times higher than that of LCCC at 0.80 and 0.85 V, respectively, indicating that high curvature fundamentally transforms site reactivity. Futher analyses unveil that curvature-induced electronic redistribution and intensified local electric fields synergistically facilitate rapid OH⁻ desorption, preventing site poisoning and accelerating reaction kinetics. The topological-defect curvature engineering provides a method for designing high-performance catalysts.

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