Galvanic Replacement Synthesis Enabled by Gallium‐Based Liquid Metal: A Powerful Route for Material Design and Versatile Applications

The precise engineering of core-shell or hollow metallic nanoarchitectures has become a central pursuit in fundamental research and advanced technologies. Among the available synthetic methods, galvanic replacement reaction (GRR) holds immense potential for engineering the composition/structure tunable nanomaterials, yet conventional solid templates impose fixed geometry, and limited reactivity, restricting both versatility and functional tunability. The emergence of liquid metal (LM) with highly reactive, fluidic, dynamic, and reconfigurable attributes offers a transformative alternative to conventional GRR. By establishing a liquid-liquid interface, LM enables the deposition of metals previously inaccessible with solid templates, while simultaneously creating a significantly milder synthetic paradigm. This review is dedicated to extracting the unique features of LM-enabled GRR (LM-GRR) to highlight a powerful and facile materials-synthesis route for diverse application scenarios. The fundamentals and mechanisms of the LM-GRR will be first introduced, followed by a detailed explanation of the uniqueness and overall programmability in terms of composition, structure, processable template, and interfacial characteristics. Representative reaction systems are systematically surveyed to illustrate their specificity and chemical versatility. Finally, we discuss functional metal materials obtained via LM-GRR for use in high-performance catalysis, flexible electronics, biomedicine, biosensing, and electromagnetic shielding areas, and conclude with perspectives on future directions.