Fig. 2. TEM images for reference cCVD Si nanoparticles (a and b) and Si nanoparticles undergoing the HSS process at pH 7.4 (d–i), 8.0 (j–l) and 9.0 (m–p) at various time intervals. For selected samples the accompanying nanoparticle size distribution histograms are included (c, q and r). Each histogram is based on analysis of 100 nanoparticles. For the pH 8.0 sample, regions are imaged to see the hollow and dense nanoparticles in one frame (j–l). At pH 8.0 and 9.0, hollow nanoparticles are the main configuration, and the TEM images showing both hollow and dense nanoparticles are not representative of the sample.