Department of Mechanical and Industrial Engineering , University of Toronto , Toronto , Ontario M5S 3G8 , Canada.
ACS Appl Mater Interfaces. 2018 Jul 5;10(26):22537-22544. doi: 10.1021/acsami.8b03776. Epub 2018 Jun 21.
In this work, the effect of humidity and water intercalation on the friction and wear behavior of few-layers of graphene and graphene oxide (GO) was studied using friction force microscopy. Thickness measurements demonstrated significant water intercalation within GO affecting its surface topography (roughness and protrusions), whereas negligible water intercalation of graphene was observed. It was found that water intercalation in GO contributed to wearing of layers at a relative humidity as low as ∼30%. The influence of surface wettability and water adsorption was also studied by comparing the sliding behavior of SiO/GO, SiO/Graphene, and SiO/SiO interfaces. Friction for the SiO/GO interface increased with relative humidity due to water intercalation and condensation of water. In contrast, it was observed that adsorption of water molecules lubricated the SiOSiO interface due to easy shearing of water on the hydrophobic surface, particularly once the adsorbed water layers had transitioned from "ice-like water" to "liquid-like water" structures. Lastly, an opposite friction trend was observed for the graphene/SiO interface with water molecules failing to lubricate the interface as compared to the dry graphene/SiO contact.
在这项工作中，使用摩擦力显微镜研究了湿度和水插层对少层石墨烯和氧化石墨烯（GO）摩擦磨损行为的影响。厚度测量表明，GO 中存在大量的水插层，这会影响其表面形貌（粗糙度和突起），而石墨烯中几乎没有观察到水插层。结果发现，在相对湿度低至约 30%时，GO 中的水插层有助于层的磨损。还通过比较 SiO/GO、SiO/石墨烯和 SiO/SiO 界面的滑动行为研究了表面润湿性和水吸附的影响。由于水插层和水的凝结，SiO/GO 界面的摩擦力随相对湿度的增加而增加。相比之下，观察到水分子吸附润滑了 SiOSiO 界面，这是由于疏水表面上的水分子易于剪切，特别是一旦吸附的水分子层从“冰状水”转变为“液态水”结构。最后，对于与水相比未能润滑界面的干燥石墨烯/SiO 接触，与水分子相比，石墨烯/SiO 界面表现出相反的摩擦趋势。
