This is a cork-based biomimetic ("copying nature") ecoceramic ("Environmentally Conscious Ceramic") made of ceria (CeO2). This is a pure ceramic, but with the hexagonal microstructure of the cork template, which is very porous and made of regular hexagonal cells ~20 microns in diameter (by comparison, a human hair is ~100 microns diameter). Cork is a sustainable material, as the bark is harvested without damaging the tree, which lives on as a carbon sink for over 200 years. The cork is then converted into the ceria ecoceramic. The image shows, from right to left, the ceria ecoceramic made of hexagonal cells, a single hexagonal cell, and the tiny ceria nanoparticles of which the ecoceramic is actually formed, with scale bars in each image. We are using this to split water to make renewable hydrogen fuel with concentrated solar energy via a solar thermochemical process.
(False colour, as this is a scanning electron microscope (SEM) image)
<a href="//commons.wikimedia.org/w/index.php?title=User:Rob_Pullar&amp;action=edit&amp;redlink=1" class="new" title="User:Rob Pullar (page does not exist)">Rob Pullar</a>
CC BY 4.0
<span class="int-own-work" lang="en">Own work</span>