New Strategy and Excellent Fluorescence Property of Unique Core–Shell Structure Based on Liquid Metals/Metal Halides

The further applications of liquid metals (LMs) are limited by their common shortcoming of silver‐white physical appearance, which deviates from the impose stringent requirements for color and aesthetics. Herein, a concept is proposed for constructing fluorescent core–shell structures based on the components and properties of LMs, and metal halides. The metal halides endow LMs with polychromatic and stable fluorescence characteristics. As a proof‐of‐concept, LMs‐Al obtained by mixing of LMs with aluminum (Al) is reported. The surface of LMs‐Al is transformed directly from Al to a multi‐phase metal halide of K3AlCl6 with double perovskites structure, via redox reactions with KCl + HCl solution in a natural environment. The formation of core–shell structure from the K3AlCl6 and LMs is achieved, and the shell with different phases can emit a cyan light by the superimposition of the polychromatic spectrum. Furthermore, the LMs can be directly converted into a fluorescent shell without affecting their original features. In particular, the luminescence properties of shells can be regulated by the components in LMs. This study provides a new direction for research in spontaneous interfacial modification and fluorescent functionalization of LMs and promises potential applications, such as lighting and displays, anti‐counterfeiting measures, sensing, and chameleon robots. liquid metals (LMs)‐aluminum (Al) materials are prepared by mixing LMs and Al. The surface of LMs‐Al is quickly transformed from Al to multi‐phase K3AlCl6 with double perovskites structure by reacting with KCl + HCl solution. The K3AlCl6 shell exhibits excellent cyan fluorescence properties under UV excitation. This provides a concept for interfacial modification and fluorescent functionalization of LMs.