Black Aerogel Based on Short-Time High-Flux He Ion Implantation

Owing to ultra-lightweight and integrable functionality, black aerogels are applied as light-shielding units in complex optical systems. However, the preparation of most black aerogels involves complex and time-consuming carbonization processes to induce carbon particles. Inspired by the barb structure of the black feathers, a simple and short-time approach by using helium (He) ion implantation to obtain black silica aerogel, which possesses microscale, biomimetic cone arrays with several microcavities, is introduced. Benefiting from this multilevel structure, only a thin surface of ≈47 µm is required to realize evident light shielding with ≈3% transmittance and ≈2% reflectivity in the visible region. This film also possessed considerable photothermal conversion, which increased to more than 65 °C from room temperature under 1 sun energy density. Meanwhile, the realization of this black surface inherits the excellent properties of the aerogel, such as porosity, high specific surface area, and low density. This work presents a simple and effective technique for preparing black surfaces based on aerogel monoliths, holding potential for use in photocatalysis, photothermal therapy, and light stealth.