Heterogeneous interfaces enable robust macroscale superlubricity of trihydric alcohols via H-bond networks and wall slip

Achieving macroscale superlubricity (friction coefficient <0.01) under high-load conditions remains a fundamental challenge due to inadequate load capacity and interfacial instability. Here, a molecularly engineered lubrication paradigm is reported that integrates in-situ passivated heterogeneous interfaces with trihydric alcohol lubricants (e.g., glycerol) to realize ultralow friction (μ ≈ 0.006) and negligible wear. Electrochemical boronizing of 304 stainless steel creates a chemically graded interface comprising a polar SiO₂ surface and a nonpolar hydrocarbon (-C_xH_y) passivation layer. Tribological tests reveal that trihydric alcohols outperform mono-/dihydric analogs by an order of magnitude in friction reduction. Molecular dynamics simulations demonstrate that their dense hydrogen-bond (HB) networks form solid-like films with exceptional load-bearing capacity (>500 MPa), while dynamic HB stability (lifetime >20 ps) and multidirectional connectivity enable wall slip at the lubricant/passivation interface, minimizing shear dissipation. This synergy of robust cohesion and interfacial slip mirrors 2D material superlubricity yet operates under high contact pressures on general engineering alloys. The work establishes a scalable strategy—combining surface boronizing with industrial-compatible trihydric alcohols—to bridge molecular design with macroscale energy-efficient applications in bearings, gears, and sustainable machinery.