NiCo Alloy Nanoparticles Anchored on Carbon Nanotube-Decorated Carbon Nanorods as a Durable and Efficient Oxygen Electrocatalyst for Zinc-Air Flow Batteries

The exploring of oxygen electrocatalysts with outstanding durability and efficiency toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is greatly desired for zinc-air flow batteries (ZAFBs). Herein, NiCo alloy-based nanoparticles anchored on carbon nanotube-decorated carbon nanorods (CNRs) used as a durable and efficient oxygen electrocatalyst for ZAFBs were obtained from the pyrolysis of NiCo metal–organic frameworks synthesized by a facile oil bath method. By tailoring the ratio of Ni²⁺ and Co²⁺, the prepared sample, Ni₂Co₂-CNR, exhibits excellent ORR (E_1/2 = 0.80 V) and OER catalytic performances (a low overpotential of 310 mV at 10 mA cm^–2). Impressively, the ZAFB assembled with a Ni₂Co₂-CNR catalyst shows a narrow voltage gap and remarkable operation durability with 1200 cycles at 5 mA cm^–2 with every cycle of 20 min.