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

Abstract 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.