Transition metal and phosphorus co-doped porous carbon as electrocatalyst for oxygen reduction

Carbon-based materials, as non-noble catalysts, have attracted extensive attention in the field of cathode catalysts for fuel cells due to their high conductivity, long-term stability, low-cost and environmental friendliness. Especially, the oxygen reduction reaction (ORR) activity of carbon materials can be significantly improved after co-doping with transition metal and heteroatoms. In this work, transition metal (Co, Fe, Ni, Mn) and phosphorus (P) co-doped porous carbon (TM-P-C) was prepared via self-assembly method combined with a carbonization process, in which polyether (F127) was introduced as soft template, phenol and formaldehyde as carbon precursor, tetraphenylphosphine bromide as phosphorus source, and nitrate as transition metal source. The electrocatalytic activity of TM-P-C for ORR in alkaline electrolyte was studied by using the rotating ring-disk electrode (RRDE) technique. The results reveal that TM-P-C exhibits high electrocatalytic performance for ORR in 0.1 mol/L KOH, and the activity follows P-Co-C＞P-Ni-C＞P-Fe-C＞P-Mn-C. Moreover, the ORR performance of P-Co-C is compared to that of commercial 20wt%Pt/C catalyst. The diffusion limiting current density of P-Co-C reaches that of 20wt%Pt/C and a negative shift of about 66 mV exists in the half-wave potential of P-Co-C as compared to 20wt%Pt/C, indicating the four-electron pathway during the ORR. The enhancement in the activity for ORR is mainly attributed to the synergistic effect of P and transition metal doping in carbon of TM-P-C. Moreover, TM-PC shows excellent long-term stability and methanol toxicity resistance, superior to that of commercial 20wt%Pt/C. © 2023 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.