Multi‐Component PtFeCoNi Core‐Shell Nanoparticles on MWCNTs as Promising Bifunctional Catalyst for Oxygen Reduction and Oxygen Evolution Reactions

The development of commercially viable fuel cells and metal-air batteries requires effective and cheap bifunctional catalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Multi-component Pt−Fe−Co−Ni nanoparticles on multi-walled carbon nanotubes (MWCNTs) were synthesized by wet chemistry route via NaBH$_4$ reduction of metal salts, followed by sintering at different temperatures. The catalyst demonstrates an excellent ORR activity and a promising OER activity in 0.1 m KOH, with a bi-functional over-potential, ΔE of 0.83 V, which is comparable to the values of Pt/C or RuO$_2$. Furthermore, it shows outstanding long-term stability in ORR and OER, namely diffusion limited current density at a potential of 0.3 V decreased just by 5.5 % after 10000 cycles in ORR. The results of the PFCN@NT$^{300}$ indicate a significant effect of the substitution of Pt by the transition metal (TM) and the formation of nanoparticles on the catalytic performance, especially in the OER.