Synthesis of highly spherical calcium carbonate nanoparticles using air nanobubbles as additives
Description
Ultrasamll nanoparticles that simultaneously exhibit narrow size distribution and high circularity are key to enabling multifunctional applications in optoelectronic systems, integrated circuits and robots. Calcium carbonate (CaCO3) nanoparticles are typical nanomaterials with various shapes and sizes have found applications in both science and technology, while controlled synthetic approaches toward nanoparticles with high circularity remain challenging. Herein, we report the synthesis of spherical CaCO3 using air nanobubbles as additives in reactive precipitation. Air nanobubbles (<100 nm, stable >5 days) were generated via a rotating packed bed. During precipitation, these nanobubbles acted as immobile impurities, directing crystal growth. This yielded spherical CaCO3 nanoparticles (6.89±0.75 nm) with calcite structure and exceptional circularity (0.97). In situ liquid-phase TEM revealed the nanobubbles' role in inducing anomalous growth, providing deep insight into spherical nanoparticle synthesis for diverse applications.
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Steps to reproduce
For TEM imaging of calcium carbonate: Focus on inconspicuous small-sized particles; avoid overemphasizing large spherical grains. This is because nanobubble content is limited, and precipitation inevitably continues during air-exposed sample preparation. For morphology records after two-month storage: Preserve samples in sealed vials after supernatant extraction. Imaging should similarly prioritize small-sized particles. In-situ liquid-phase TEM: Easily captures spherical particle formation but requires two separate injections to ensure focusing completion before reaction termination during the second injection. Nanobubble pH experiments: Require storage protected from light at consistent temperatures.
Institutions
- Beijing University of Chemical Technology