Water-Mediated Conversion of BaTiO Nanoparticles into BaCO Nanorods in Electrospun Polymer Fibers: Implications for Carbon Capture Applications.

Under ambient conditions and in aqueous environments, transformations of nanoparticle-based ferroelectric components can raise important stability issues that are relevant for applications as multilayer capacitors, flexible piezoelectrics, or biomedical devices. We show that X-ray amorphous BaTiO nanoparticles that were grown by flame spray pyrolysis and which can be incorporated into electrospun polymer fibers undergo incongruent Ba dissolution in the presence of water. At pH > 5 and in contact with air, corresponding Ba solutes spontaneously convert into crystalline BaCO needles to produce characteristic nano- and microstructures. We compared the reactivity of amorphous BaTiO nanoparticle powders with those of nanocrystals after annealing-induced crystallization. The stability of aqueous nanoparticle-polymer formulations, which are typically part of nanoparticle encapsulation in polymers and electrospinning, was included in this analysis. Nanoparticle size, crystallinity, surface area, the presence of carbonaceous surface contaminants, and the effect of surface passivation with polymers are addressed to underline the critical role of condensed water during the synthesis, storage, and processing of BaTiO nanoparticle-based composites.