Fabricating La0.7Sr0.3MnO3 nanofibers by electrospinning as efficient and stable oxygen reduction electrocatalysts for direct ammonia fuel cells

Porous La 0.7 Sr 0.3 MnO 3 nanofibers are synthesized via facile electrospinning for DAFC cathodes. • The fuel cell reaches a peak power density of 40 mW cm -2 . • Half/full-cell durability tests confirm the good stability of La 0.7 Sr 0.3 MnO 3  nanofiber. Synthesizing anti-ammonia poisoning oxygen reduction reaction (ORR) electrocatalysts with low cost and high activity is pivotal for the development of high-performance direct ammonia fuel cells (DAFCs). ABO 3 -type perovskites are deemed as promising non-noble metal alternatives to noble-metal catalysts, thanks to their facile preparation, tunable structure and intrinsic ORR activity. Nevertheless, conventional ABO₃ perovskites synthesized via the sol-gel method are plagued by low specific surface area and severe particle agglomeration, which drastically suppress their practical ORR performance in DAFCs. Herein, one-dimensional (1D) La 0.7 Sr 0.3 MnO 3 nanofibers were fabricated via PVP-assisted electrospinning to overcome the bottlenecks of traditional perovskite catalysts. Results demonstrate that the half-wave potential (0.76 V) and limiting-current density (5.78 mA cm −2 ) of La 0.7 Sr 0.3 MnO 3 nanofibers are superior to those of the nanoparticle counterparts, which primarily benefits from its 1D porous structure enhancing the mass/electron transfer and exposing more active sites. The DAFC with a La 0.7 Sr 0.3 MnO 3 cathode yields a peak power density of 40 mW cm −2 , comparable to the DAFC using a Pt/C cathode. Moreover, the good stability of La 0.7 Sr 0.3 MnO 3 nanofibers has been experimentally verified by the half-cell and whole-cell durability tests. This work confirms that 1D porous La 0.7 Sr 0.3 MnO 3 nanofibers are a competitive non-noble-metal ORR catalyst, offering a feasible strategy for developing high-performance DAFCs.