  Future decades will experience tons of silicon waste from various sources,
with no reliable recycling route. The transformation of bulk silicon into SiO2
nanoparticles is environmentally significant because it provides a way to
recycle residual silicon waste. To address the needs of silicon recycling, we
develop a top-down approach that achieves 100% conversion of bulk silicon to
silica nanoparticles with outcome sizes of 8-50 nm. In addition to upcycling
the potential of silica, our method also possesses several advantages, such as
simplicity, scalability and controllable particle size distribution. Many
fields of science and manufacturing, such as optics, photonics, medical, and
mechanical applications, require size-controllable fabrication of silica
nanoparticles. We demonstrate that control over temperature and hydrolysis time
has a significant impact on the average particle size and distribution shape.
Additionally, we unravel the process of nanoparticle formation using a
theoretical nucleation model and quantum density functional theory
calculations. Our results provide a theoretical and experimental basis for
silica nanoparticle fabrication and pave the way for further silicon
conservation research.
