ZIF-8 derived nitrogen, phosphorus and sulfur tri-doped mesoporous carbon for boosting electrocatalysis to oxygen reduction in universal pH range

It is highly urgent but challenging to develop the alternative oxygen reduction reaction (ORR) catalysts to the traditional noble-metals (such as Pt). In this study, a facile and cost-efficient route is designed to construct nitrogen, phosphorus and sulfur tri-doped mesoporous carbon (NPSpC) by direct pyrolysis of ZIF-8 after pretreatment with sodium phytate solution and dodecyl mercaptan. The resultant NPSpC exhibits a large specific surface area (1641 m2/g) and excellent catalytic activity toward ORR. The values for its onset potential (0.923 V vs RHE), half wave potential (0.821 V vs RHE) and limiting diffusion current density (4.89 mA/cm2) in 0.1 M KOH are close to those of commercial Pt/C (0.945 V, 0.839 V and 5.01 mA/cm2, respectively). It also displays the superior methanol tolerance and long-time stability to Pt/C in alkaline medium. Additionally, NPSpC demonstrates the comparable ORR performance to and much better stability than the commercial Pt/C in acidic and neutral solutions. The desirable ORR performance is originated from the synergistic effects including the tri-doping of N, P and S heteroatoms, the large active surface area, the more exposed catalytic sites, well mesoporous nanostructure for sufficient accessibility of the reactants and rapid mass transfer.