For further interpretation of the Raman spectra, peak deconvolution was conducted with a four-peak model which takes two "peak shoulders" into consideration. These two additional small peaks centred at around 1500 cm -1 (D'' band) and 1200 cm -1 (I band) arise from the activation of forbidden vibration modes due to structural disorder, consistent with previous studies We note that a simple two-peak model was not able to provide good fits across the full series of carbons (Figure ).