Synergetic FeCo nanorods embedded in nitrogen-doped carbon nanotubes with abundant metal-NCNT heterointerfaces as efficient air electrocatalysts for rechargeable zinc-air batteries

Commercialization of rechargeable zinc-air batteries (ZABs) is blocked by low stability and battery performance. Herein, we synthesized a series of cobalt/iron nanorods embedded into nitrogen-doped carbon nanotubes and utilized them as air electrodes for rechargeable ZABs. The electrochemical results suggest that the FeCo-alloyed structure exhibits better stability and electrocatalytic activities toward the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) than the Fe-NR/NCNT and Co-NR/NCNT. This is ascribed to the presence of more metal-NCNT heterointerfaces, resulting in more active sites for catalyzing ORR and OER. The Fe0.33Co0.67-NR/NCNT requires only 285 mV overpotential to deliver 10 mA cm(-2)in the OER catalysis indicating a better catalytic activity compared to Co-NR/NCNT (298 mV) and Fe-NR/NCNT (363 mV) as well as the benchmark of the IrO2(313 mV). Moreover, Fe0.33Co0.67-NR/NCNT with a half-wave potential of 857 mVvs.RHE (comparable to commercial Pt/C (853 mVvs.RHE)) outperforms Fe-NR/NCNT (842 mVvs.RHE) and Co-NR/CNT (839 mVvs.RHE). Consequently, the assembled rechargeable ZAB from Fe0.33Co0.67-NR/NCNT (164 mW cm(-2)) exhibits higher battery performance and stability than Co-NR/NCNT (70 mW cm(-2)), Fe-NR/NCNT (89 mW cm(-2)) and Pt/C-IrO2(71 mW cm(-2)). Furthermore, the all-solid-state ZAB fabricated from Fe0.33Co0.67-NR/NCNT shows a considerably high battery performance (54 mW cm(-2)) and stability.