Dual template-approach of hierarchical porous carbon with high N-doping structure for oxygen reduction reaction and supercapacitor

Abstract

A novel strategy has been developed to prepare hierarchical porous carbon with ultra-high N-doping through a dual template-approach, including simple polycondensation of precursor between melamine and formaldehyde, introduction of magnesium oxide and titanium dioxide dual templates, carbonization, and removal of template. The dual template-approach creates hierarchical nanopores in the prepared nanoporous carbons (TMCs) and improves the specific surface area of the TMCs (960 m2/g). Additionally, cations and anions of MgO and TiO2 can improve thermal stability of N atoms, leading to high N content of TMCs (11.7–26.31 at.%). With excellent surface area and high N content, the prepared TMCs achieves unique electrochemical performances. For oxygen reduction, the onset potential of TMC800 is 1.02 V (vs. RHE); the kinetic current density (Jk) of TMC800 is 6.78 mA cm−2 (0.6 V); for Zn-air batteries, the maximum power density of TMC800 is 87 mW cm−2 (vs. 70 mW cm−2 of commercial Pt/C catalyst). For supercapacitor, TMC900 has high specific capacitance (805F g−1), and its symmetrical supercapacitor has an energy density of 9.8 Wh kg−1 at a power density of 250 W kg−1.