Oxygen Deficient LaMn_0.75Co_0.25O_3-δ Nanofibers as an Efficient Electrocatalyst for Oxygen Evolution Reaction and Zinc-Air Batteries

The rational design of efficient and durable oxygen evolution reaction (OER) is important for energy conversion and storage devices. Here, we develop a two-step calcination method to prepare cobalt nanoparticles uniformly dispersed on perovskite oxide nanofibers and to tune oxygen vacancies in perovskite LaMn_0.75Co_0.25O_3-δ nanofibers. The obtained product shows enhanced activity toward OER. In particular, the oxygen deficient LMCO-2 catalyst prepared by a two-step calcination shows excellent OER performance that is 27.5 times that of the LMO catalyst and is comparable to that of the commercial RuO₂ catalyst. It also demonstates good stability because of its novel structure, abundant oxygen vacancies, and larger number of metal ions with a high oxidation state. As an air electrode for a flexible zinc-air battery, the cell with the LMCO-2 catalyst delivers a higher power density of 35 mW cm^-2 and excellent cycling stability for 70 h. Moreover, the cell exhibits excellent flexibility under different bending conditions.