Sprayable Ultrablack Coating Based on Hollow Carbon Nanospheres

Inexpensive, easy-to-implement coatings exhibiting extremely low reflectance within a broad spectral range, and good adhesion to substrates are in high demand for high-precision optical instruments solar energy harvesting. Herein, we demonstrate highly absorbing coating based on hollow carbon nanospheres (HCSs). The formed via simple high-performing air-spraying process with tailored paint formulation containing HCSs as an pigment fluororesin binder. By optimizing the pigment/binder mass ratio (P/B), produce functional that exhibit absorptance up 0.985 aluminum sheets of grade 2 (according ISO 2409 standard). excellent obtained results from their hierarchical nano- microscale surface morphology, providing refractive index gradient air–coating interface well remarkable light trapping performance. former is due structure spheres, which preserved after addition binder because size particles larger than holes shell HCSs. latter attributed micronodules micropits by agglomeration HCSs, enhances absorption multiple scattering.