Engineering of hollow mesoporous Fe-graphitic carbon Nitride@CNTs for superior electrocatalytic oxygen reduction reaction

Abstract

The engineering of hollow mesoporous materials has recently gained increasing interest due to their tremendous potential as an attractive nanoplatform to catalyze the oxygen reduction reaction (ORR), a key reaction in H2-O2 fuel cells. Herein, a hollow mesoporous Fe-graphitic carbon nitride supported on carbon nanotubes (Fe-C3N3@CNTs) was constructed via polymerization of 1,3,5-triazine and cyanuric chloride on the surface of the CNTs under microwave irradiation. The Fe-C3N3@CNTs composite dominated the 4e-ORR route and demonstrated a 40 mV anodic shift in E1/2ORR relative to 20% Pt catalyst due to its large surface area, good conductivity, mesoporous architecture, and high density of Fe-N4 sites. Furthermore, Fe-C3N3@CNTs demonstrated exceptional methanol tolerance and durability during ORR. Theoretical analyses revealed that Fe-C3N3 catalytic moieties easily transferred the e- density into π* orbital of O2, lowering the energy barrier for the O2 adsorption and desorption with active site, endowing 4e- ORR. This work offered a simple method of constructing a superior ORR electrocatalyst from inexpensive raw precursors, paving the way for future use of nanostructures in fuel cells.