Schematic depiction of metal-induced pit formation in water. (a) Owing to the catalytic activity of metallic particles, electrons are transferred from the Ge bulk to water to reduce dissolved O2 to H2O molecules, which leads to an enhanced oxidation around the particles. (b) GeO2 dissolves in water, leaving (111) microfacets.
Kawase et al. Nanoscale Research Letters 2013 8:151 doi:10.1186/1556-276X-8-151