One-step, in situ formation of WN-W₂C heterojunctions implanted on N doped carbon nanorods as efficient oxygen reduction catalyst for metal-air battery

Transition metal nitrides and carbides have attracted intensive attentions in metal-air battery application due to their metallic electron transport behavior and high chemical stability toward the oxygen reduction reaction (ORR). Herein, the polyoxometalate@polyaniline composite derived WN-W₂C heterostructured composite (WN-W₂C@pDC) has been fabricated through an in situ nitriding-carbonization strategy, with WN-W₂C nanoparticles implanted on N doped carbon nanorods. As-fabricated WN-W₂C@pDC demonstrates prominent electrocatalytic performance towards ORR and excellent cycling stability in metal-air battery, which possesses positive half-wave potential and large diffusion limiting current density (0.81 V and 5.8 mA·cm⁻²). Moreover, it demonstrates high peak power density of 157.4 mW·cm⁻² as Al-air primary cathode and excellent stability at the discharge–charge test (> 500 h) of Zn-air secondary battery. The excellent activity and durability of WN-W₂C@pDC catalyst should be attributed to the combined effect of intimate WN-W₂C heterointerfaces, unique embedded nanoparticles structure, and excellent electrical media of N doped carbon, confirmed by a series of contrast experiments.