Fe, N co-doped carbonaceous hollow sphere with self-grown carbon nanotubes as a high performance binary electrocatalyst

A novel kind of non-precious metal nanohybrid FeNC-900 is synthesized by hard-template with pyrolysis method using Fe-doped ZIF-8 as the precursor. The FeNC-900 has a superstructure of Fe, N co-doped carbonaceous hollow spheres crosslinked by some self-grown carbon nanotubes. The Fe, N co-doped carbonaceous matrix provides the binary electrocatalytic active sites of Fe–N–C and N-doped carbon as the electrocatalytic active sites. And the microstructure of carbonaceous hollow spheres as well as the crosslinked carbon nanotubes not only lead to the large surface area exposing the electrocatalytic active sites but also benefit the transport of the electrons and electrolyte ions and the stability of the microstructure of the nanocomposite. Thus, FeNC-900 shows the comparable electrocatalyst activities with that of state-of-the-art commercial Pt/C for ORR and RuO₂ for OER respectively in both alkaline and acidic electrolytes due to the synergetic binary electrocatalytic active sites as well as the hierarchical porous texture. More importantly, the low ΔE (= E_{10 mA cm} ⁻² - E_{-3 mA cm} ⁻²) of 0.691 and 0.784 V in 0.1 M KOH and 0.1 M HClO₄ electrolytes for FeNC-900, respectively, indicating its fascinating bifunctional electrocatalytic activities for ORR and OER in both alkaline and acidic electrolytes.