Continuous precipitation of ceria nanoparticles from a continuous flow micromixer

Cerium oxide nanoparticles were continuously precipitated from a solution of cerium(III) nitrate and ammonium hydroxide using a static microchannel T-mixer. T-mixer synthesis results were compared with synthesis results from batch precipitation. Findings show that the method of mixing is important in the ceria precipitation process. Uniform porous film structures and nanorods were produced when the particle chemistry was synthesized using T-mixing followed by spin coating. Batch mixing, when using higher NH₄OH feed concentrations followed by spin coating, was characterized by the heavy agglomeration of nanoparticles. Similar, high aspect ratio nanorods were produced when feed conditions in both batch mixing and T-mixing were identical demonstrating that the momentum effects of continuous microchannel T-mixing did not impact the synthesis process. In addition, it was found that the micromixing approach reduced the exposure of the Ce(OH)₃ precipitates to oxygen, yielding hydroxide precipitates in place of CeO₂ precipitates. The key advantage of the micro-scale T-mixing approach is higher throughput which is important for the scaling of ceria nanoparticle production.