Super‐Black Coatings on Aluminum: Structure–Optical Property Relationships, Fabrication Routes, and Applications

Aluminum is a critical engineering platform for optical, aerospace, and energy technologies, but its high reflectivity limits use wherever strong light absorption is required. Super‐black coatings, defined here as surfaces with a band‐averaged total hemispherical reflectance of 1% or less over a stated wavelength range, suppress that reflection either by restructuring the aluminum itself or by adding an intrinsically absorbing layer, and most effectively by combining the two. This review connects the structure–optical property relationships, fabrication routes, and application spaces of super‐black aluminum surfaces, with emphasis on how chemical etching, laser texturing, anodization, electroless nickel–phosphorus plating, carbon‐based coatings, and their hybrids transform optical performance. It sets out the physical mechanisms underlying broadband absorption, the characterization methods that quantify it, and the trade‐offs among absorptance, durability, corrosion resistance, and scalable processing, and it separates the applications whose definitions of blackness conflict, from solar‐thermal conversion and stray‐light suppression to infrared camouflage and emerging energy conversion. It also identifies the scarcity of optical data remeasured after environmental exposure as the main gap between laboratory demonstrations and qualified hardware. By centering aluminum as the substrate rather than treating it as a generic support, the review provides a design framework for next‐generation super‐black aluminum surfaces.