RuFe Alloy Nanoparticle-Supported Mesoporous Carbon: Efficient Bifunctional Catalyst for Li-O₂and Zn-Air Batteries

The design and fabrication of bifunctional catalysts with low cost and high efficiency is a great challenge for the practical application of Li-O2 batteries. This work presents a bifunctional electrocatalyst consisting of RuFe nanoparticles embedded in high-surface-area nitrogen-doped mesoporous carbon (RuFe@NC). The RuFe@NC-900 catalyst exhibits a specific surface area (677 m2 g-1), pore diameter (9.52 nm), and high pore volume (0.3 cm3 g-1). The catalyst displays high oxygen reduction and evolution reaction activity and exhibited excellent bifunctional activity (ΔE) of 0.73 V vs RHE compared to the benchmark catalyst, 40 wt % Pt/C + RuO2 substantiates the excellent catalytic activity as an oxygen electrode. The excellent bifunctional activity is attributed to the synergistic effect arising from RuFe@NC type sites, and the high electrical conductivity of the support material was key to tuning the catalytic activity. The potential practical application is further demonstrated by using it as an air cathode for rechargeable metal-air batteries. The Li-O2 battery constructed with the optimized RuFe@NC-900(5h) cathode exhibited robust reversibility with negligible discharge voltage loss. As a result, the discharge-specific capacity of 11,129 mAh g-1 at a current density of 100 mA g-1 shows a practical approach to explore the high-rate capability by constructing optimal cathode electrodes. In addition, the rechargeable zinc-air battery with RuFe@NC-900(5h) as a bifunctional catalyst exhibits high activity and stability during battery discharge, charge, and cycling processes. Therefore, RuFe@NC can be a potential air cathode for non-aqueous and aqueous rechargeable metal-air batteries.