Hyper-Dispersion-Driven Fabrication of Ultrablack Coatings

Ultrablack coatings traditionally rely on complex micro/nanoengineering, limiting scalability and durability. Herein, we present a hyper-dispersion-based approach for the creation of micro- and nanostructured ultrablack coatings (solar absorptance of over 99%) via controlled aggregation of carboxylated carbon nanotubes (C–CNTs) in high-concentration colloidal systems. Molecular dynamics simulations revealed that the self-assembled hierarchical structures arise from the C–CNT aggregation. The use of high-temperature-resistant epoxy resin enhances adhesion, environmental resistance, and mechanical durability. The coatings maintained high solar absorptance and structural integrity under extreme thermal cycling and water flushing. In addition, we demonstrated that the coatings have excellent photothermal conversion efficiency, significantly raising the temperature of coated silk textiles under low solar irradiation and increasing the voltage output of thermoelectric devices by four times compared with uncoated ones. This scalable, efficient fabrication method requires no extra materials or complicated steps, demonstrating broad potential for solar energy and thermal management.