Hydroxyl-assisted globally spontaneous dynamic oxygen migration on biphenylene

Abstract

Dynamic covalent interfaces (DCIs) can autonomously adjust their internal structures and dynamically respond to changes in the external environment, thus holding broad application prospects in drug delivery, molecular detection, and interface catalysis. However, the dynamic properties of such DCIs greatly rely on the localized exchanges or formations of chemical bonds, seriously constraining the adaptive response efficiency. To transcend the limitations of the dynamic two-dimensional (2D) scales, employing the experimentally synthesized biphenylene monolayer as a prototype, we systematically study the hydroxyl-assisted globally spontaneous dynamic oxygen migration on biphenylene interface based on the first-principles calculations and machine-learning-based molecular dynamics (MLMD) simulations. The calculated results indicate that the stable dangling oxygen atoms on the biphenylene monolayer can attract the proton in the interfacial water, which in turn undergoes a water dissociation process and produces hydroxyl groups on the biphenylene interface. Assisted by the hydroxyl groups, the dangling oxygen atoms can achieve long-range migration, exhibiting notably low energy barriers (0.09 eV, 0.04 eV) due to the reversible proton transfer reactions. Therefore, the local dynamic covalent behaviors of oxygen atoms on the biphenylene interface are broken with the oxygen atoms migrating between the adjacent C4 rings. More importantly, the charge density difference and Bader charge analysis demonstrate that the presence of hydroxyl groups significantly enhance the stability of the dangling oxygen, effectively reducing energy barriers of oxygen migration compared to epoxy on the biphenylene interface. Furthermore, the MLMD trajectories visually show the process of realizing large-area DCIs on the biphenylene monolayer. Our work not only clarifies the oxygen-related dynamic behavior of the biphenylene interface, but also provides new ideas for the realization of large-area dynamic covalent materials (DCMs) on other carbon-based or 2D materials.