Ultrablack Coating Is 10× Darker Than Other Very Black Materials

MIT engineers have developed a material they say is 10× blacker than any ultrablack material that has previously been reported. The material is made from vertically aligned carbon nanotubes (CNTs) that the team grew on a surface of sodium chloride-etched aluminum foil. The foil captures at least 99.995% of any incoming light. The discovery of the ultrablack material came about by accident, in the course of work to grow CNTs on aluminum. When the aluminum was exposed to air, it became coated with a layer of oxide that insulated it, blocking it from being able to conduct electricity and heat. The researchers sought ways to remove the oxide layer and discovered a solution with salt. They soaked the aluminum foil in...