Boosting oxygen reduction reaction kinetics by Fe–V dual sites in ultrafine V-Fe3C nanoparticles for aluminum-air batteries

The electrochemical oxygen reduction reaction (ORR) plays a crucial role in air-breathing energy conversion systems. However, its kinetics are constrained by a multistep proton-coupled electron transfer process, wherein the adsorption of the OOH* introduces high energy barriers. Herein, we present N-doped carbon-supported ultrafine V-incorporated Fe 3 C nanoparticles (V-Fe 3 C@NC) featuring abundant Fe coupling with V, serving as reaction sites for efficient ORR. Experimental characterizations confirm the incorporation of V species leads to a significant enhancement in ORR kinetics. The prepared V-Fe 3 C@NC electrocatalyst demonstrates exceptional ORR activity with a half-wave potential of 0.91 V. Density functional theory calculations elucidate that the synergy between Fe and V sites facilitates direct O–O bond breakage, circumventing the formation of the OOH* and resulting in lower ORR energy barriers. Moreover, the aluminum-air (Al-air) batteries derived from ultrafine V-Fe 3 C@NC nanoparticles display outstanding performance with a high open-circuit voltage of 1.92 V and a large specific capacity of 2309 mAh g −1 under the air environment. The elucidation and understanding of synergy in dual reaction sites present a novel approach for the rational design of supported metal nanoparticle electrocatalysts for energy-related applications.