Effect of Heteroatoms on Pseudocapacitance for N/O Co-doped Porous Carbon in an Alkaline Aqueous Electrolyte

The primary objective of this investigation is to assess the electrochemical properties of porous carbon, concurrently doped with nitrogen and oxygen, featuring a diverse array of surface heteroatoms. We synthesized this type of porous carbon material from Houttuynia cordata, subjected to procedures of nitrogen infusion and activation. Our findings indicate a strong relationship between the pseudocapacitance of the dually doped porous carbon and the concentration of pyridinic-nitrogen. As the pyridinic-nitrogen content increases, the pseudocapacitance first increases due to the growing tendency of active sites. After the pyridinic-nitrogen/carbon atomic ratio reaches 0.027, the pseudocapacitance decreases because the conductivity of the carbon material decreases. Density functional theory simulations indicate that the band gap of pyridinic-nitrogen-doped graphene is 0.021 eV, which is larger than that of nitrogen-free graphene. The increased band gap makes electronic transitions less likely, and the conductivity decreases.