Aluminum is produced in chemical electrolysis by the Hall–Heroult process using carbon-based materials in electrodes (cathode and anode). The amorphous calcined petroleum coke is normally used as the carbon material. During the electrolysis of alumina, a voltage drop of about 0.15–0.25 V occurs due to the formation of gas bubbles at the anode which therefore reduces the electrolysis reaction kinetics. To improve the electrolysis efficiency, graphite material is partly used in both the cathode and anode. To further improve the efficiency of the electrolysis, the graphite may be replaced by graphene oxide (GO) and reduced graphene oxide (RGO) because of their outstanding electrical, mechanical and chemical properties. As the demand for graphene oxide and graphene is increasing daily, large-scale and economic processes should be developed to meet this challenge. This study was carried out to produce GO and RGO from natural high-purity graphite (HPG) by applying oxidation and reduction processes through chemical and mechanical exfoliation processes. In the chemical exfoliation process, multi-metal alloys of zinc, iron, aluminum and silicon are used as the reductant instead of using hazardous chemical materials. In the mechanical exfoliation process, a planetary ball mill is used to exfoliate the natural graphite by purging gaseous oxidants and reductants such as O₂ and H₂ for the oxidation of GO and the reduction of RGO, respectively. The morphology, structure and composition of HPG, GO and RGO have been characterized using different analytical techniques, such as X-ray diffraction, scanning electron microscopy, and transmission electron microscopy with selected area electron diffraction, micro-Raman spectroscopy and Fourier-transform infrared spectroscopy. The number of layers of the GO and RGO samples has been determined based on the characterization data and found to be four to five layers.

中文翻译：

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铝业天然石墨化学机械剥离制备GO和RGO的研究

铝是通过Hall-Heroult工艺在化学电解过程中使用电极（阴极和阳极）中基于碳的材料生产的。通常将无定形的煅烧石油焦用作碳材料。在氧化铝电解过程中，由于在阳极上形成气泡而导致约0.15-0.25 V的电压降，从而降低了电解反应动力学。为了提高电解效率，在阴极和阳极中都部分使用了石墨材料。为了进一步提高电解效率，由于石墨的出色的电，机械和化学性能，可以用氧化石墨烯（GO）和还原的氧化石墨烯（RGO）代替石墨。随着对氧化石墨烯和石墨烯的需求每天都在增加，应该发展大规模和经济的过程来应对这一挑战。通过化学和机械剥离工艺，通过氧化和还原工艺，利用天然高纯石墨（HPG）生产GO和RGO。在化学剥离过程中，锌，铁，铝和硅的多金属合金用作还原剂，而不使用危险的化学材料。在机械剥离过程中，使用行星式球磨机通过清除气态氧化剂和还原剂（例如O）来剥离天然石墨 铁，铝和硅用作还原剂，而不使用危险的化学材料。在机械剥离过程中，使用行星式球磨机通过清除气态氧化剂和还原剂（例如O）来剥离天然石墨 铁，铝和硅用作还原剂，而不使用危险的化学材料。在机械剥离过程中，使用行星式球磨机通过清除气态氧化剂和还原剂（例如O）来剥离天然石墨₂和H _2分别用于GO的氧化和RGO的还原。HPG，GO和RGO的形态，结构和组成已使用不同的分析技术进行了表征，例如X射线衍射，扫描电子显微镜和具有选定区域电子衍射，显微拉曼光谱和傅里叶变换红外的透射电子显微镜光谱学。已经基于特征数据确定了GO和RGO样本的层数，发现是4到5层。