Rawal Aditya, Che Man Siti H, Agarwal Vipul, Yao Yin, Thickett Stuart C, Zetterlund Per B
NMR Facility, Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, NSW 2052, Australia.
Cluster for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
ACS Appl Mater Interfaces. 2021 Apr 21;13(15):18255-18263. doi: 10.1021/acsami.1c01157. Epub 2021 Apr 2.
Investigation of highly oxidized graphene oxide (GO) by solid-state nuclear magnetic resonance (NMR) spectroscopy has revealed an exceptional level of hitherto undiscovered structural complexity. A number of chemical moieties were observed for the first time, such as terminal esters, furanic carbons, phenolic carbons, and three distinct aromatic and two distinct alkoxy carbon moieties. Quantitative one-dimensional (1D) and two-dimensional (2D) C{H} NMR spectroscopy established the relative populations and connectivity of these different moieties to provide a consistent "local" chemical structure model. An inferred 2 nm GO sheet size from a very large (∼20%) edge carbon fraction by NMR analysis is at odds with the >20 nm sheet size determined from microscopy and dynamic light scattering. A proposed kirigami model where extensive internal cuts/tears in the basal plane provide the necessary edge sites is presented as a resolution to these divergent results. We expect this work to expand the fundamental understanding of this complex material and enable greater control of the GO structure.
通过固态核磁共振（NMR）光谱对高度氧化的氧化石墨烯（GO）进行研究，揭示了一种前所未有的、迄今未被发现的结构复杂性。首次观察到了许多化学基团，如末端酯基、呋喃碳、酚碳以及三种不同的芳香族和两种不同的烷氧基碳基团。定量一维（1D）和二维（2D）C{H} NMR光谱确定了这些不同基团的相对丰度和连接性，以提供一个一致的“局部”化学结构模型。通过NMR分析从非常大的（约20%）边缘碳分数推断出的2 nm GO片层尺寸与通过显微镜和动态光散射确定的>20 nm片层尺寸不一致。提出了一种kirigami模型，其中基面上广泛的内部切割/撕裂提供了必要的边缘位点，作为对这些不同结果的一种解决方案。我们期望这项工作能扩展对这种复杂材料的基本理解，并实现对GO结构的更好控制。
