Oxidation Mechanism and Protection Strategy of Ultrathin Indium Selenide: Insight from Theory

Ultrathin indium selenide (InSe), as a newly emerging two-dimensional material with high carrier mobility and a broad absorption spectrum, has been the focus of current research. However, the long-term environmental instability of atomically thin InSe seriously limits its practical applications. To develop an effective strategy to protect InSe, it is crucial to reveal the degradation mechanism at the atomic level. By employing density functional theory and ab initio molecular dynamics simulations, we provide an in-depth understanding of the oxidation mechanism of InSe. The defect-free InSe presents excellent stability against oxidation. Nevertheless, the Se vacancies on the surface can react with water and oxygen in air directly and activate the neighboring In–Se bonds on the basal plane for further oxidation, leading to complete degradation of InSe into oxidation products of In2O3 and elemental Se. Furthermore, we propose an efficient strategy to repair the Se vacancies by thiol chemistry. In this way, the repaired surface can resist oxidation from oxygen and retain the original high electron mobility of pristine InSe simultaneously.超薄硒化铟（InSe）作为一种新兴二维材料，兼具高载流子迁移率与宽吸收光谱，是当前的研究热点。然而，原子级超薄InSe的长期环境不稳定性严重制约了其实际应用。为开发有效的InSe防护策略，在原子层面揭示其降解机制至关重要。本研究借助密度泛函理论（Density Functional Theory, DFT）与从头算分子动力学（Ab Initio Molecular Dynamics, AIMD）模拟，深入阐明了InSe的氧化机制。无缺陷的InSe展现出优异的抗氧化稳定性，但表面的硒空位可直接与空气中的水和氧气发生反应，并激活基面内相邻的In–Se键以推动进一步氧化，最终使InSe完全降解为三氧化二铟（In₂O₃）与单质硒。此外，本研究提出一种基于硫醇化学的高效硒空位修复策略，经该方法修复后的表面可抵御氧气氧化，同时保留原始InSe固有的高电子迁移率。