Tribology Research Institute, State Key Laboratory of Traction Power, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu610031, China.
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China.
ACS Nano. 2023 Feb 14;17(3):2497-2505. doi: 10.1021/acsnano.2c10084. Epub 2023 Feb 3.
The mechanical performance and surface friction of graphene oxide (GO) were found to inversely depend on the number of layers. Here, we demonstrate the non-monotonic layer-dependence of the nanowear resistance of GO nanosheets deposited on a native silicon oxide substrate. As the thickness of GO increases from ∼0.9 nm to ∼14.5 nm, the nanowear resistance initially demonstrated a decreasing and then an increasing tendency with a critical number of layers of 4 (∼3.6 nm in thickness). This experimental tendency corresponds to a change of the underlying wear mode from the overall removal to progressive layer-by-layer removal. The phenomenon of overall removal disappeared as GO was deposited on an H-DLC substrate with a low surface energy, while the nanowear resistance of thicker GO layers was always higher. Combined with density functional theory calculations, the wear resistance of few-layer GO was found to correlate with the substrate's surface energy. This can be traced back to substrate-dependent adhesive strengths of GO, which correlated with the GO thickness originating from differences in the interfacial charge transfer. Our study proposes a strategy to improve the antiwear properties of 2D layered materials by tuning their own thickness and/or the interfacial interaction with the underlying substrate.
研究发现，氧化石墨烯（GO）的力学性能和表面摩擦与层数呈反比关系。在这里，我们证明了沉积在天然氧化硅衬底上的 GO 纳米片的纳米磨损阻力与层数呈非单调关系。当 GO 的厚度从约 0.9nm 增加到约 14.5nm 时，纳米磨损阻力最初表现出先减小后增大的趋势，其中有一个关键的 4 层（约 3.6nm 厚）。这种实验趋势对应于磨损模式从整体去除到逐层去除的变化。当 GO 沉积在具有低表面能的 H-DLC 衬底上时，整体去除现象消失，而较厚 GO 层的纳米磨损阻力始终较高。结合密度泛函理论计算，发现少层 GO 的耐磨性与衬底的表面能有关。这可以追溯到 GO 对衬底的粘附强度的依赖性，这与界面电荷转移引起的 GO 厚度有关。我们的研究提出了一种通过调节自身厚度和/或与底层衬底的界面相互作用来提高二维层状材料抗磨损性能的策略。
