Solid-State Gelation for Nanostructured Perovskite Oxide Aerogels

Abstract

Fabricating nanostructured perovskite oxide aerogel to access a dramatic increase in the specific surface area has proved challenging despite continued efforts. Here, we report a versatile and general method for synthesizing nanosized perovskite oxides. Specifically, we used bimetallic “LaMnOx” oxide nanoparticles as the precursors to synthesize r-LaMnO[subscript 3±δ] perovskite oxide aerogels by way of a solid-state gelation process, generating aerogels with specific surface areas exceeding 74.2 m[superscript 2] g oxide[superscript –1]. The r-LaMnO[subscript 3±δ] aerogel featured an increased Mn valence state compared to the bulk form of the material, facilitating the oxygen reduction reaction kinetics in alkaline medium. At 0.8 VRHE, the r-LaMnO[subscript 3±δ] aerogel achieved a mass activity of 66.2 A g oxide[superscript –1], which is 153-fold higher mass activity compared to the conventional bulk LaMnO3. The solid-state gelation synthesis route was extended to other perovskite oxides with high compositional diversity, including LaMnO[subscript 3], LaFeO[subscript 3], LaNiO[subscript 3], LaCoO[subscript 3], La[subscript 0.5]Sr[subscript 0.5]CoO[subscript 3], and La[subscript 0.5]Sr[subscript 0.5]Co[subscript 0.5]Fe[subscript 0.5]O[subscript 3], thereby demonstrating the versatile nature of our synthetic route for the fabrication of a wide range of nanostructured perovskite oxides.