Manipulating single oxygen at Cu2O-island surfaces through thermomechanical coupling

Single oxygen diffusion event, the most favorable rate-limiting process of epitaxial Cu₂O oxide-island layer-by-layer growth kinetics, may lead to oxygen defects due to thermomechanical coupling. However, the formation rules of oxygen defects remain unclear, preventing the realization of controllable oxygen defects on oxide-island surfaces. Here, we utilize the first-principles method to investigate the formation rules of intrinsic oxygen defects in the surface layers of prototypical metal-oxide (Cu₂O) surfaces under thermomechanical coupling effects. We establish the thermodynamic phase diagram for oxygen-defect-modulated Cu₂O surfaces, enabling the prediction of the growth of oxide islands during Cu oxidation, which aligns closely with in-situ environmental transmission electron microscopy (ETEM) experiment observations. By exploring the strain-modulated phase diagrams, we propose a potential strategy for controlling the type and concentration of oxygen defects on oxide-island surfaces. Our findings provide an effective approach to theoretically understanding the oxidation process of metal surfaces, thus enabling the computational design of high-performance corrosion-resistant surfaces.