Thermally degraded polyurea as cathode catalyst of an anion exchange membrane fuel cell

Abstract

Cobalt-doped, MDI (methylene diphenyl diisocyanate)-based polyurea (Co-MPUr) is prepared from the condensation polymerization between p-phenylene diamine (PDA) and MDI in the presence of cobalt ions (Co(II)), which is calcined to become the Co, N–co-doped carbonaceous cathode catalysts (Co–N–Cs). Fourier Transform Infrared Spectrometer (FT-IR) is used to prove the successful synthesis of the MDI-based polyurea (MPUr) structure. The porous and coral-like morphologies of the calcined Co-MPUr are characterized by transmission electron microscope (cryo-TEM) and high-resolution transmission electron microscope (HR-TEM), and field-emission scanning electron microscope (FE-SEM). The extremely high specific surface area (> 900 m2 g–1) and porosity are analyzed by BET analyzer. Sharp graphite diffraction peaks are found in the x-ray diffraction (XRD) patterns, resulting from the high crystallinity, and Raman spectra demonstrate higher G-band intensity than D-band. The cathode catalyst performance (ORR: oxygen reduction reaction) of the Co–N–Cs compared with commercial Pt/C catalysts are characterized by current-voltage (CV) and linear sweeping voltage (LSV) curves. The single cell using Co–N–C catalyst as cathode catalyst (CC) demonstrates a high maximum power density (Pmax) of 327.6, compared to 286.4 mW cm−2 of Pt/C.