Biomass carbon with defective structures as effective ORR catalyst for DMFC

Abstract

Oxygen reduction reaction (ORR), as an important reaction carried out on the cathode of direct methanol fuel cells (DMFC), directly affects the performance of the cell. Previous experimental studies have shown that there are some interactions between the defect structure and N doping to promote the ORR performance of the catalysts. In this work, the binder was first utilized to reduce the lignin content in the cotton straw (CS) system, thereby increasing the defective structure of the carbon substrate. Here, we obtained 5C-NP-Fe catalysts by increasing the defectivity of the carbon substrate through binder. The coordination environment surrounding the Fe-N₄ sites is optimized by the synergistic action of the N and P atoms and the faulty structure, as shown by DFT theoretical calculations. In alkaline medium, half-wave potentials as high as 0.88 V in the three-electrode system and a peak power density of 10.8 mW cm⁻² in a direct methanol fuel cell at 60℃. Compared to a 20 wt% commercial Pt/C catalyst (0.84 V, 7.5 mW cm⁻²), 5C-NP-Fe showed good ORR activity. The binder modification strategy provides a simple and green approach to the structural optimization of biomass-based catalysts.