The present work focused on the determination of texture, morphology, crystallinity, and gas adsorption characteristics of porous graphene prepared from rice husks ashes at different stabilization temperature. The stabilization temperature applied in this work is 100 °C, 200 °C, 300 °C, and 400 °C to convert rice husk into rice husk ashes (RHA). Chemical activation was adopted at temperature 800 °C using potassium hydroxide (KOH) as dehydrating agent at (1:5) impregnation ratio to convert RHA into rice husk ashes-derived graphene (GRHA). The resultant GRHA were characterized in terms of their morphological changes, SSA, crystallinity, and functional group with TEM, the BET method, Raman spectroscopy, and XRD analysis, respectively. Results from this study showed that the SSA of the GRHA at stabilization temperature 200 °C (1556.3 m2/g) is the highest compared to the other stabilization temperature. Raman spectroscopy analysis revealed that all GRHA samples possess D, G, and 2D bands, which confirm the successful synthesis of the rice husks into porous graphene-like materials, known as GRHA. Appearance of diffraction peak in XRD at 44.7° indicating the graphitic structure of all the GRHA samples. Meanwhile, the TEM images of GRHA200 exhibited wrinkled structures due to the intercalation of oxygen and a few layers of graphene flakes. These wrinkled structures and graphene layers are the other factors that lead to the highest SSA of GRHA200 compared to other prepared samples GRHA. Furthermore, the adsorption capacity of CH4 for GRHA200 is up to 43 cm3/g at 35 bar and ambient temperature, almost double the adsorption capacity performance of GRHA400 at the same operating pressure and temperature.

    Abstract
    1 Introduction
    2 Materials and methods
        2.1 Fabrication of RHA at different pre-treatment temperatures
        2.2 Activation of RHA
        2.3 Characterization
        2.4 Methane adsorption measurement
    3 Results and discussion
        3.1 Porosity characteristics and gas adsorption measurements
        3.2 Raman analysis
        3.3 X-ray diffraction analysis
        3.4 Structural morphology
        3.5 Study of methane adsorption capacity on GRHA samples
    4 Conclusion
    Acknowledgements 
    References

• Faten Ermala Che Othman(Advanced Membrane Technology Research Centre (AMTEC), School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM))
• Mohd Shafri Ismail(Advanced Membrane Technology Research Centre (AMTEC), School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM))
• Norhaniza Yusof(Advanced Membrane Technology Research Centre (AMTEC), School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM))
• Sadaki Samitsu(Data‑driven Polymer Design Group, Research and Services Division of Materials Data and Integrated System (MaDIS), National Institute for Materials Science (NIMS))
• Mohd Zamri Yusop(Department of Materials, School of Mechanical Engineering, Faculty of Engineering, School of Mechanical Engineering, Universiti Teknologi Malaysia (UTM))
• Nur Fatihah Tajul Arifin(Advanced Membrane Technology Research Centre (AMTEC), School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM))
• Nur Hashimah Alias(Department of Oil and Gas Engineering, Faculty of Chemical Engineering, Universiti Teknologi Mara)
• Juhana Jaafar(Advanced Membrane Technology Research Centre (AMTEC), School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM))
• Farhana Aziz(Advanced Membrane Technology Research Centre (AMTEC), School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM))
• Wan Norharyati Wan Salleh(Advanced Membrane Technology Research Centre (AMTEC), School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM))
• Ahmad Fauzi Ismail(Advanced Membrane Technology Research Centre (AMTEC), School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM))