Solid-State Gelation for Nanostructured Perovskite Oxide Aerogels

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-LaMnO3 +/-delta perovskite oxide aerogels by way of a solid-state gelation process, generating aerogels with specific surface areas exceeding 74.2 m(2) g(oxide)(-1). The r-LaMnO3 +/-delta 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 V-RHE, the r-LaMnO3 +/-delta aerogel achieved a mass activity of 66.2 A g(oxide)(-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 LaMnO3, LaFeO3, LaNiO3, LaCoO3, La0.5Sr0.5CoO3, and La0.5Sr0.5Co0.5Fe0.5O3, thereby demonstrating the versatile nature of our synthetic route for the fabrication of a wide range of nanostructured perovskite oxides.