Synthesis and NOx sensing evaluation of hollow/porous La0.8Sr0.2MnO3 microspheres

Abstract

To improve the nitric oxide (NO) gas reaction properties, we synthesized microspherical La_0.8Sr_0.2MnO₃ (LSM) particles. We investigated the NO sensing properties of NO_x sensors fabricated using electrodes based on hollow/porous LSM (hp-LSM) and solid sphere LSM particles. The hp-LSM particles were synthesized using a novel process combining spray pyrolysis with carbonization using citric acid. The resulting particles were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM), and their specific surface area was estimated using Brunauer–Emmett–Teller (BET) theory. The particle and pore size of the hp-LSM particles were estimated to be 1–3 μm and 100–500 nm, respectively, and their highest specific surface area was determined to be 6.8 m² g⁻¹. Sintered pellets made from hp-LSM particles had a relative density of 68% and a broad pore size distribution between 100 and 1000 nm, estimated by the Archimedes method and mercury intrusion porosimetry measurements. The hp-LSM-based gas sensing electrode exhibited a faster NO response/recovery time than the one based on solid LSM. This synthetic method is expected to be widely applicable to other materials, and hollow/porous particles may be used for various applications such as gas sensors, batteries and chemical reactors.