From micro-to-nano in charged water microdroplets: unveiling steps in the weathering of minerals†

The recent discovery of the rapid conversion of micron-sized common minerals to nanoparticles in charged water microdroplets has attracted significant attention. Here, we studied this micro-to-nano transition as a function of applied electric potential and tip-to-substrate distance using high-resolution transmission electron microscopy (HRTEM). Our observations revealed that the fragmentation progresses through distinct stages, from larger particles to flower-like intermediates and finally to nanoparticles. The results suggested the need for a critical droplet size to initiate the disintegration process, with Coulomb explosion playing a significant role in particle scission. Our results provide new insights for the efficient green synthesis of nanomaterials.