Fe-N carbon black oxide as catalysts for oxygen reduction reaction and application to room temperature direct lignin fuel cells

The progress in developing inexpensive and highly effective catalysts is vital for overcoming the current limitations of oxygen reduction reaction (ORR) and the practical application of fuel cells. This study constructed a three-dimensional (3D) composite catalyst using etra-β-(8-quinolinoxy) iron phthalocyanine (EFePc) as the sites of catalytic activity, nitrogen-doped reduced graphene oxide (NRGO) as the basal plane, and oxidized carbon black (OCB) as the intercalating agent. The morphological and structural characteristics of the composite catalyst were thoroughly analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis, Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Evidence from the results suggested that the 3D catalyst has been synthesized successfully. The EFePc-NRGO/OCB exhibited a half-wave potential (E 1/2 ) of 0.80 V, closely approximating those of commercial Pt/C (20 wt%). The average electron transfer number was 3.77, indicating a 4-electron transfer process. Furthermore, when the catalyst was applied to direct lignin fuel cells (DLFCs), the maximum power density reached 247.87 mW/m² which far exceeded Pt/C (53.13 mW/m²). This offers a novel perspective for the advancement of high-efficiency non-noble metal catalysts and the high-value utilization of lignin.