A nacre-inspired structural material with thermochromic properties and mechanical robustness by atomic-level design

). Coupled with a machine-learning-based image-recognition system, the NAC leverages its thermochromic properties to deliver a rapid fire warning within 9 s at 250°C, which is significantly faster than traditional electronic fire alarms. Its layered structure effectively impedes oxygen flow, achieving an oxygen-limiting index of 50%, and thus ensuring excellent flame-retardant performance. This design delays the combustion peak and reduces the heat-release value, thereby enhancing the flame-retardant performance. This work demonstrates the effective integration of a structural and functional design for active early fire warning and passive flame retardancy, paving the way for structural materials in advanced fire-warning systems in challenging environments.