Facile fabrication of ultra-low density,high-surface-area,broadband antireflective carbon aerogels as ultra-black materials

Carbon aerogels with various densities, even as low as 20 mg/cm³, were fabricated by pyrolysis of organic aerogels formed by aqueous condensation of resorcinol and formaldehyde. It was found that carbon aerogels with the density below 70 mg/cm³ exhibited the total reflectance values of typically less than 0.24 % across wavelengths in the range of 400–2000 nm. The change of antireflective properties between the lowest-density carbon aerogel monolith and its powder coating was discussed. Furthermore, we studied the effect of the density on the structure and antireflective property of carbon aerogels. As a result, the low-density carbon aerogels showed broadband low-reflectivity and high absorption to incident light.