Graphene Oxide Synthesis: Optimizing the Hummers and Marcano Methods
Graphene Oxide Synthesis: Optimizing the Hummers and Marcano Methods
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DOI：
10.1166/nnl.2020.3074
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发表时间：
2020-01-01
影响因子：
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通讯作者：
Nair, Rahul R.
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文献类型：
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作者：
Al-Ruqeishi, Majid S.;Mohiuddin, Tariq;Nair, Rahul R.
以具有成本效益的高效方式制造氧化石墨烯（GO）仍然具有挑战性。一些研究人员通过修改Hummers的方法制造由少量层组成的GO，如下：（1）尽量减少使用NaNO 3，有毒气体的来源;和（2）使用MnO 2作为氧化剂。其他研究人员通过Marcano的方法制造GO，其中KMnO 4取代MnO 2。这里，使用9：1体积比的H2SO 4/H3 PO 4。KMnO 4的作用是在石墨层间缓慢扩散，并在整个氧化过程中充当过氧化剂。对于大规模生产，在H2SO 4中使用KMnO 4存在爆炸风险，并且石墨氧化不完全。我们克服了这些挑战，通过生长GO片表现出类似于3.1 +/- 0.2 μ m的平均尺寸厚度，通过优化作为氧化剂离子源的KMnO 4和H2SO 4/H3 PO 4的量，在Hummers和Marcano方法的修改中，不使用NaNO 3。优化反应时间和使用小石墨片优化氧化以提供高产率的GO片。X-射线衍射显示，对于GO，层间d-间距为5.7埃，对于较少量的剩余非剥离石墨颗粒，层间d-间距为2.9埃。傅里叶变换红外光谱显示，石墨域内的拉伸振动没有峰，特别是对于通过修改的Hummers方法生长的GO。紫外-可见光谱和拉曼光谱表明，与先前的研究相比，具有相互连接的碳原子的sp（2）域的层数以及边缘平面处的波纹和主要缺陷等无序减少。GO片的拉曼Id/IG比为1.21至1.75。根据X射线光电子能谱从C 1 s核心能级推导出的碳/氧原子比（R-C/O）范围为0.43至6.84。
Fabricating graphene oxide (GO) in a cost-effective, efficient manner remains challenging. Some researchers manufacture GO that is comprised of a small number of layers by a modification of Hummers' method, as follows: (1) minimize use of NaNO3, a source of toxic gases; and (2) use MnO2 as the oxidizer. Other researchers fabricate GO by Marcano's method, where KMnO4 substitutes for MnO2. Here, one uses a 9:1 volume ratio of H2SO4/H3PO4. The role of KMnO4 is to diffuse slowly in the graphite interlayer and act as a peroxidation agent throughout the oxidation. For large-scale production, there is an explosion risk from using KMnO4 in H2SO4, and incomplete graphite oxidation. We overcame these challenges by growing GO sheets exhibiting an average size thickness of similar to 3.1 +/- 0.2 mu m by optimizing the quantity of KMnO4 and H2SO4/H3PO4 as oxidizer ion sources, in modifications of both the Hummers and Marcano methods, without using NaNO3. Optimizing the reaction time and using small graphite flakes optimized oxidation to afford a high yield of GO sheets. X-ray diffraction showed an interlayer d-spacing of 5.7 angstrom for GO and 2.9 angstrom for the lesser quantity of remaining non-exfoliated graphite grains. Fourier-transform infrared spectroscopy showed no peaks for stretching vibrations within the graphitic domains, especially for GO grown via the modified Hummers method. Ultraviolet-visible and Raman spectroscopy showed that the number of layers with sp(2) domains of interconnected carbon atoms, and disorder such as ripples and major defects at the edge planes, decreased compared to prior research. The Raman Id/Ig ratio of the GO sheets ranged from 1.21 to 1.75. The carbon/oxygen atomic ratio (R-C/O), deduced from the C 1 s core level as per X-ray photoelectron spectroscopy, ranged from 0.43 to 6.84.