MXene is considered as a promising solid lubricant due to facile shearing ability and tuneable surface chemistry. However, it faces challenges in high‐humidity environments where excessive water molecules can significantly impact its 2D structure, thus deteriorating its lubricating properties. In this work, the self‐assembled monolayers are formed on MXene by surface chlorination (MXene‐Cl) and fluorination (MXene‐F), and their friction behaviors in high/low humidity are investigated. The results indicate that MXene‐F and MXene‐Cl can maintain a relatively constant friction coefficient (CoF) (MXene‐F ∼0.76, MXene‐Cl ∼0.48) under both high (75%) and low (25%)‐relative humidity (RH) environments. Meanwhile, the MXene‐F and MXene‐Cl display a lower CoF than the pristine MXene (MXene CoF∼1.18) in high humidity. The above phenomena are mainly attributed to the preservation of its 2D layered structure, the increased layer spacing, and superficial partial oxidation for SAMs‐functionalized MXene under high humidity during friction. Interestingly, MXene‐Cl with moderate water resistance has a lower CoF than that of MXene‐F with complete water resistance. The nanostructured water adsorption capacity and larger interlayer spacing of MXene‐Cl make it exhibit a lower CoF compared to MXene‐F. The findings of this study offer valuable guidance for tailoring MXene by surface chemical functionalization as an efficient solid lubricant in high humidity.

中文翻译：

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通过自组装单分子层保持 MXene 的二维结构，实现高湿度下的高效润滑


由于容易的剪切能力和可调节的表面化学性质，MXene 被认为是一种有前途的固体润滑剂。然而，它在高湿度环境中面临挑战，过多的水分子会显着影响其二维结构，从而恶化其润滑性能。在这项工作中，通过表面氯化（MXene-Cl）和氟化（MXene-F）在MXene上形成自组装单分子层，并研究了它们在高/低湿度下的摩擦行为。结果表明，MXene-F 和 MXene-Cl 在高（75%）和低（25%）相对湿度下都能保持相对恒定的摩擦系数（CoF）（MXene-F ∼0.76，MXene-Cl ∼0.48） (RH) 环境。同时，MXene-F 和 MXene-Cl 在高湿度下表现出比原始 MXene (MXene CoF∼1.18) 更低的 CoF。上述现象主要归因于SAMs功能化MXene在摩擦过程中高湿度下其二维层状结构的保存、层间距的增加以及表面部分氧化。有趣的是，具有中等耐水性的 MXene-Cl 的 CoF 低于具有完全耐水性的 MXene-F。 MXene-Cl 的纳米结构水吸附能力和较大的层间距使其表现出比 MXene-F 更低的 CoF。这项研究的结果为通过表面化学功能化将 MXene 定制为高湿度下的高效固体润滑剂提供了宝贵的指导。