Selective Activation of S or N-Containing Carbon Segments by Alkalic or Acidic Activators
To date, the activation reactions of heteroatom-containing carbon segments have not been systematically studied. Here, activation of S,N dual-doped petroleum coke (SNC) by acidic (CO2), alkalic (KOH and NH3), and neutral (H2O) activators is investigated. The reactions between activators and S/N-containing segments are similar to the typical acid–base reactions. SNC exhibits higher activation reactivity as compared to the undoped carbon, thus leading to a high SSA even at low activation temperature. S-Containing groups exhibit higher reactivity to alkalic activators, and N-containing groups show higher reactivity to acidic activators. Compared to the activation by KOH, activation by CO2 and NH3 can lead to a high retention of S and N content, thus resulting in higher area-normalized capacitance in a three-electrode supercapacitor. Our results give better understanding of the activation mechanism of heteroatom-doped carbons and provide an easy method to selectively remove or keep heteroatoms during activation.