There are five different kinds of phosphorus functionalities over carbon materials as displayed in Fig. . They are phosphate, alkoxy phosphine, phosphine oxide, phosphonic and phosphinic acid. It has been reported in the literature that the P-doped carbon has delivered the specific capacitance of 385 F g -1 at 0.2 A g -1 in 1 M H2SO4 which is comparatively higher than 1 M Na2SO4 (203 F g -1 at 0.3 A g -1 ) . This is because of the fact that the size of H + ions is smaller than Na + and higher ionic conductivity as well as mobility of H + ions. As a result, the pseudocapacitive influence of H + ions are stronger than Na + ions. Additionally, oxygen atoms which are directly bonded with phosphorus significantly participate in faradaic reactions with H + ions to produce the protonated version. It has been apparently revealed that not only the doped phosphorus atoms but also the oxygen functionalities are responsible for the amplified supercapacitive performance of P-doped carbon materials. The possible electrochemical mechanism of phosphorus-based carbon materials in acidic electrolyte is expressed as shown below: