Surface chemistry of UHMCFs was analyzed through an AxisUtltradld model X-ray photoelectron spectroscopy (XPS) with anachromatic Mg Kα X-ray as radiation source. Curve fitting was carriedout using a non-linear least squares fitting program with a Gaussian/Lorentzian mix function and background subtraction. The C1s electronbinding energy corresponding to graphitic carbon was referenced at284.6 eV for calibration [19,32].