Imaged above (top) are different solutions containing fixed concentrations of Ge NPs with varying quantities of H2O2 (the quantities increase as you move left to right).1 Note that the cuvette on the far left comprises of Ge NPs dispersed in pure water.
The synthesis of the Germanium nanoparticles (Ge NPs) was done via laser pyrolysis (bottom left), a “gas phase process for the synthesis of nanomaterials,” and the size of the Ge NPs was controlled by an etching procedure based on the oxidation of the Ge NPs.12 Adding Ge NPs to solutions of H2O2 cause the Ge NPs to be surrounded by an oxide layer (bottom right), which can be easy removed by treating the Ge NPs with HCl (bottom right).1
Kim, S.; Walker, B.; Park, S.; Choi, H.; Ko, S.; Jeong, J.; Yun, M.; Lee, J.; Kim, d.; Kim, J. Size tailoring of aqueous germanium nanoparticle dispersion. Nanoscale. 2014. DOI: 10.1039/C4NR01596G
Chiruvolu, S.; Li, W.; Ng, K.; Du, K.; Ting, K.; McGovern, W.E.; Kambe, N.; Mosso, R.; Drain, K. Laser pyrolysis - a platform technology to produce nanoscale materials for a range of product applications. Nanotech. 2006, 1, 325-328.