Step-Induced Strain in Curved van der Waals Nanoribbons.

Surface atoms generally experience tensile stress owing to reduced coordination. For example, Pt(111) steps can induce up to 5.5% strain and nearly a 50-fold activity enhancement. This step picture, however, is fundamentally altered in van der Waals (vdW) layered materials, where weak interlayer coupling largely relaxes step-induced strain. Here, we revisit vdW structures and show that one-dimensional curved edges intrinsically sustain localized step-induced strain. Density functional theory calculations reveal that narrowing the terrace width enables localized compressive strain and favorable hydrogen adsorption. Using PtSe2 as a model system, we synthesize monolayer nanoribbons with high-curvature edges and link their average curvature to the effective terrace width through an equivalent terrace model. Further, microelectrochemical measurements verify the resulting enhancement in hydrogen evolution activity. Our work reveals that discrete in-plane atomic steps induce spatially heterogeneous strain and modulate catalytic performance in vdW materials.