Sign of Mechanochemical Curvature Governing O2 Activation Mechanisms and Reactivity on Rippled Supports

Abstract

Two-dimensional (2D) materials are inherently prone to forming ripples and wrinkles that create regions of nonzero curvature-a mechanochemical landscape arising from intrinsic deformation-thereby modulating their electronic structure and a range of associated properties. Such curvature effects have implications for stability, quantum processes, and adsorption phenomena. The influence of curvature-treated as a vector descriptor distinguishing positive and negative curvature-on reactivity remains underexplored, particularly in the context of small-molecule activation and multistep catalytic reactions. Here, we investigate rippled N-doped graphene and quantify how curvature, viewed as a local mechanochemical deformation, modulates O 2 reactivity on single-atom sites, denoted as M-N-C (M = Fe, Co, Mn, Pt), using density functional theory. We find that the sign of curvature determines the O 2 activation mode: for Mn and Fe, negatively curved regions (mountain-shaped) favor an η 2 side-on configuration, whereas positively curved regions (valley-shaped) promote an η 1 end-on mode. In contrast, Co and Pt exhibit only curvature-independent η 1 binding. The η 2 mode observed for Fe and Mn resembles molecular O 2 adducts in transition-metal complexes. curvature overpotential + -