Utilization of charged microdroplets for the controlled rapid synthesis of hollow sodium chloride single crystals

Charged microdroplets are favored in microfluidic control, biomedicine, chemistry and materials processing due to their unique physicochemical environment, including interface double layers, high electric fields, surface concentration enrichment, and more. Herein, we investigated the crystallization of charged sodium chloride microdroplets and achieved the formation of hollow single crystals in a single-step process lasting only a few seconds, without the use of templates. Additionally, we discussed the plausible crystal growth mechanism, which appears to be an unconventional outward-inward growth process. The crystallization of charged microdroplets generated via electrospray can lead to the formation of hollow single crystals, wherein surface charges govern the surface ion concentration.