Interlayer Electron Redistribution Engineering for Ultralow Friction in 2D Electrides

Qi, Jingcheng;Materzanini, Giuliana;Rignanese, Gian-Marco;Righi, Maria;Wang, Junjie
(2025) Advanced Functional Materials — Vol. 36, n° 26, p. e25865 (2025)

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Authors
  • Qi, JingchengState Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072 P. R. China
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  • Materzanini, GiulianaUCLouvain
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  • Rignanese, Gian-MarcoUCLouvain
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  • Righi, MariaDepartment of Physics and Astronomy University of Bologna Bologna 40127 Italy
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  • Wang, Junjieorcid-logoState Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072 P. R. China
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Abstract
(en) Friction accounts for up to 30% of global energy consumption, underscoring the urgent need for superlubricity in advanced materials. 2D electrides feature cationic layers separated by 2D confined anionic electrons. Ab initio calculations reveal that interlayer friction correlates with cationic charge and sliding-induced charge redistribution. Remarkably, the 2D electride Ba 2 N exhibits lower interlayer friction than graphene despite stronger interlayer adhesion, contradicting conventional tribological understanding. This anomaly stems from electron redistribution serving as the dominant energy dissipation pathway. Deep potential molecular dynamics (DPMD) simulations show that incommensurate twisted interfaces (2°< < 58°) in Ba 2 N achieve structural superlubricity by suppressing out-of-plane buckling and energy corrugation. Notably, a critical normal load of 2.3 GPa enables barrier-free sliding in commensurate Ba 2 N (= 0°), with an ultralow shear-to-load ratio of 0.001, suggesting superlubricity potential. Furthermore, electron doping effectively reduces interlayer friction by controllably modulating stacking energies. These findings establish 2D electrides as a transformative platform for energy-efficient tribology, enabling scalable superlubricity through twist engineering, load adaptation, or electrostatic gating. This work advances the fundamental understanding of electron-mediated friction, with Ba 2 N serving a model for cost-effective, high-performance material design.
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Qi, J., Materzanini, G., Rignanese, G.-M., Righi, M., & Wang, J. (2025). Interlayer Electron Redistribution Engineering for Ultralow Friction in 2D Electrides. Advanced Functional Materials, 36(26), e25865. https://doi.org/10.1002/adfm.202525865 (Original work published 2025)