A highly active and durable PtCoFe/nitrogen-incorporated carbon skeleton catalyst evolved from HA-CoFe-ZIF template for methanol electrooxidation

Zeolite imidazolate frameworks (ZIFs) are a subclass of metal–organic frameworks (MOFs) containing N element, which are always exploited to prepare N-incorporated carbon materials containing rich carbon nanotubes (CNTs) via the pyrolysis. Humic acid layers are regarded as a natural GO-like material due to similar laminate size and thickness, physical and chemical structures, surface polarity, and activity to graphene oxide (GO). Here, a layered humate-ZIF (HA-CoFe-ZIF) composite template is elaborately designed and first constructed by a hydrothermal method using sodium humate as the substrate. An N-incorporated carbon skeleton (NCS) support assembled by CNTs and graphene layers is then achieved after the segmented pyrolysis and acid etching. Afterwards, a PtCoFe/NCS electrocatalyst with high catalytic activity and cycling stability for methanol oxidation reaction (MOR) is purposefully synthesized by loading PtCoFe nanoparticles on the NCS surface via ethylene glycol-sodium borohydride (EG-NaBH 4 ) double reduction. The supported catalyst constructs a composite structure with good dispersibility of metal nanoparticles on the NCS surface due to the oriented coordination bonding between metal and nitrogen incorporated in the NCS. The large specific surface and good electrical conductivity of the NCS support together guarantee high MOR electrocatalytic activity, stability, and CO tolerance ability of PtCoFe nanoparticles.