Direct integration of nanostructures into macroscopic substrates is very important for their practical applications. In this work, we report a simple method that can be introduced for the Sn‐catalyzed growth of alumina nanowires on ceramic substrates such as porous disk, monolith, and foam. Our study focuses on the role of the Sn catalysts in the formation mechanisms governing nanowire growth. Using the proposed approach, hair‐ or grass‐like tufts of 20 nm diameter nanowires grow on the surface of the ~3 μm diameter Sn particles, in a tip growth mechanism. The nanowires of α‐phased polycrystalline structure grow and are packed via a complex process involving batch‐by‐batch, branching, and amalgamation growth. The detailed observations reveal that the Sn catalyst is key to tailoring the growth patterns of the nanowires. In addition, cathodoluminescence studies highlight the potential optical applications of the alumina nanowires.

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