Nano-Science Center, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark; Department of Chemical Engineering, Delft University of Technology, Van Der Maasweg 9, Delft 2629 HZ, The Netherlands.
Nano-Science Center, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
J Colloid Interface Sci. 2019 Nov 15;556:458-465. doi: 10.1016/j.jcis.2019.08.089. Epub 2019 Aug 26.
The unambiguous determination of the chemical functionality over graphene oxide (GO) is important to unleash its potential applications. However, the mapping of oxygen functionalities distribution remains to be unequivocally determined because of highly inhomogeneous non-stoichiometric structures and ultra-thin layers of GO. In this study, we report an experimental observation of the spatial distribution of oxygen functional groups on monolayer and multilayer GO using AFM-IR, atomic force microscopy coupled with infrared spectroscopy. Overcoming conventional IR diffraction limit for several micrometers, the novel AFM-IR reaches high spatial resolution ∼20 nm and could detect IR absorption on ∼1 nm thickness of monolayer GO. With nanoscale chemical mapping, the distribution of different oxygen functional groups is distinguished with AFM-IR over the GO surface. It allows us to observe that these oxygen functional groups prefer to sit on the fold areas, in discrete domains and on the edges of GO, which gave more insights into its chemical nature. The determination of the position of functional groups through precise imaging contributes to our understanding of GO structure-properties relations and paves the way for targeted tethering of polymers, biomaterials, and other nanostructures.
明确确定氧化石墨烯（GO）的化学功能对于发挥其潜在应用至关重要。然而，由于 GO 具有高度不均匀的非化学计量结构和超薄层，其氧官能团分布的映射仍然需要明确确定。在这项研究中，我们使用原子力显微镜-红外光谱（AFM-IR）报告了对单层和多层 GO 上氧官能团空间分布的实验观察。该新型 AFM-IR 克服了传统红外衍射的几微米限制，达到了高空间分辨率约 20nm，并能够检测单层 GO 约 1nm 厚度的红外吸收。通过纳米级化学映射，AFM-IR 可以区分 GO 表面上不同氧官能团的分布。这使我们能够观察到这些氧官能团更喜欢位于折叠区域、离散域和 GO 的边缘，这使我们更深入地了解了其化学性质。通过精确成像确定官能团的位置有助于我们理解 GO 的结构-性能关系，并为聚合物、生物材料和其他纳米结构的靶向连接铺平道路。
