This work combines experimental atomic force microscopy (AFM) and density functional theory (DFT) simulations to study oxidized-metal (oxidized copper & titanium) and 2D-material (graphene & MoS₂) interfaces. Combining AFM and DFT allowed identifying the interfacial interaction and established a correlation between tribological behavior, interfacial charge distribution, and variations in the potential energy profile with sliding along the metal/2D-materials interfaces. The TiO₂ (rutile) and CuO (cupric oxide) metal oxides were mostly found to chemisorb along the interface with the 2D-materials. Both the metal-oxide counter-surfaces (TiO₂ and CuO) exhibited higher friction force and adhesion on graphene than on MoS₂. The CuO surface was inferred to be copper rich based on comparison with DFT simulations. The interfacial electronic charge distribution and relative energy change were identified to strongly influence sliding and adhesive behavior between oxidized-metal/2D-material contacts when considering only electronic effects in the DFT simulations. More homogenous interfacial charge distribution/sharing and lower surface energy variation, as found on the MoS₂ surfaces, were identified to lower friction and adhesion. Non-electronic effects not captured by simulations were found to likely dominate interfacial shear strength measurements experimentally. Therefore, MoS₂ should be used in interfacial applications involving TiO₂ and copper-rich CuO surfaces requiring lower adhesion and friction.

Graphical abstract

中文翻译：

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金属氧化物/二维材料接触的界面相互作用和摩擦学行为

这项工作结合了实验原子力显微镜 (AFM) 和密度泛函理论 (DFT) 模拟来研究氧化金属（氧化铜和钛）和二维材料（石墨烯和 MoS ₂）界面。结合 AFM 和 DFT，可以识别界面相互作用，并建立摩擦学行为、界面电荷分布和势能分布变化与沿金属/2D 材料界面滑动之间的相关性。发现 TiO ₂（金红石）和 CuO（氧化铜）金属氧化物大多沿与 2D 材料的界面进行化学吸附。与在 MoS ₂上相比，金属氧化物对立面（TiO ₂和 CuO）在石墨烯上表现出更高的摩擦力和附着力. 根据与 DFT 模拟的比较，推断出 CuO 表面富含铜。当在 DFT 模拟中仅考虑电子效应时，界面电荷分布和相对能量变化被确定为强烈影响氧化金属/2D 材料接触之间的滑动和粘附行为。更均匀的界面电荷分布/共享和更低的表面能变化，如在 MoS ₂表面上发现的，被确定为降低摩擦和粘附。发现模拟未捕获的非电子效应可能在实验上主导界面剪切强度测量。因此，MoS ₂应用于涉及 TiO _{2 的}界面应用 和富含铜的 CuO 表面，需要较低的附着力和摩擦力。

图形概要