Fig. 1. Schematic diagram of the fabrication processes and the morphology of silk-based single-component nacre-like composite material.

(A to D) Silk fibroin solution is extracted from silkworm cocoons and then undergoes bidirectional freezing process. (E to H) The as-prepared silk aerogel with lamellar structures is annealed by water vapor at room temperature, then compressed to achieve densification, and lastly presents as the Silk nacre. (I and J) Scanning electron microscopy (SEM) images of the cross sections of silk aerogel show its long-range aligned lamellar structures (inset is an optical photograph). (K) SEM image of the cross section of the Silk nacre shows its nacre-like architectures (inset is an optical photograph).