Solid-phase preparation of defective carbon supported PtNi alloy electrocatalyst and analysis of its oxygen reduction mechanism

Abstract

In the present work, PtNi-loaded defective carbon (Pt/ZnPPC) was prepared by solid-phase method. Carbon support with specific defect types, such as Zn metal nitrogen carbon (ZnPPC850), N-doped carbon (ZnPPC950) and defective carbon (ZnPPC1050), were selectively obtained by optimizing the pyrolysis temperature to explore the effect of defect types on oxygen reduction reactions (ORR). Electrochemical measurements showed that the half-wave potential of the PtNi metal nanoparticle-loaded ZnPPC1050 catalyst (PtNi-ZnPPC1050) outperformed the commercial JM-Pt/C by 35 mV, and by 45 mV compared to the PtNi-loaded ZnPPC950 catalyst (PtNi-ZnPPC950), suggesting that the defects in the ZnPPC1050 support resulting from the evaporation of N by pyrolysis can interact well with Pt metal electrically, allowing the PtNi nanoparticles to be uniformly distributed. Meanwhile, the defects lead to the carrier containing a large number of active sites making its catalytic performance even much better than the pyridine nitrogen sites in ZnPPC950. The carbon defect structure is loosened and porous with high specific surface area, which can effectively load PtNi nanoparticles and enhance the mass transfer. We obtained a new bimetallic oxygen reduction catalyst loaded with PtNi on defective carbon and elucidated the effect of five-membered ring carbon defect structure and N-doped structure on metal-carrier interaction.