The effect of heat treatment and vacuum conditions on the textural properties and electrochemical performance of commercially available activated carbons (ACs) was investigated. The AC after post-heat treatment was characterized by nitrogen adsorption–desorption, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy measurements. The ACs treated under vacuum conditions exhibit a higher specific surface area and micropore surface area than those treated under nitrogen atmospheric pressure without significantly affecting the graphite structure of the AC. Under 800 °C temperature and vacuum conditions (AC-V800), the AC with the highest Brunauer– Emmett–Teller surface area of 1951.9 m2 g−1 (16.4% improvement relative to that of the original AC (1677.2 m2 g−1)) was obtained. This is attributed to the removal of oxygen-containing functional groups and volatile matters in the carbon by thermal treatment under vacuum conditions. Consequently, the electric double-layer capacitor using ACs treated under vacuum conditions (1 kPa) at 800 °C (AC-V800) shows considerably improved electrochemical performance in terms of higher specific capacitance and better cycling stability at a high working voltage (3.1 V), compared to the nitrogen-treated and commercial ACs.

    Abstract
    1 Introduction
    2 Experimental
        2.1 Material preparation
        2.2 Characterizations
        2.3 Electrochemical measurements
    3 Results and discussion
        3.1 Physical characteristics
        3.2 Electrochemical properties
    4 Conclusion
    Acknowledgements 
    References

• Junam Kim(Department of Chemistry, Kunsan National University)
• Hoai Van T. Nguyen1(Department of Chemistry, Kunsan National University)
• Gyung Jin Bahk(Department of Food and Nutrition, Kunsan National University)
• Kyungwon Kwak(Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Korea University, Department of Chemistry, Korea University)
• Kyung‑Koo Lee(Department of Chemistry, Kunsan National University)