Synthesis of bimetallic MOFs via interface control using gallium-based liquid metal.

Metal-organic frameworks (MOFs) are porous crystalline materials whose composition and structure can be tuned for catalysis, sensing, and optoelectronic applications. Incorporating two different metal ions into a single framework can broaden the functionalities of MOFs. However, conventional solvothermal synthesis typically requires high temperature and long reaction times, while electrochemical anodic dissolution is limited by solid anodes that can only supply a single metal source. For active metals such as Mg, the rapid formation of a passivation layer on solid anodes hinders the continuous release of metal ions. Here, we introduce a liquid metal interface-controlled electrochemical strategy using a fluid Mg-Ga alloy anode, overcoming the single-metal limitation of conventional anodic deposition. The self-healing surface of liquid gallium and its high surface tension induce electrocapillarity and Marangoni flow under an applied bias, enabling dynamic and spatially uniform release of Mg²⁺ ions that co-assemble precisely with Zn²⁺ from solution. Under an optimized bias of 0.3 V, the resulting bimetallic ZnMg-MOF-74 exhibits high crystallinity, nanosheet morphology, and uniform metal distribution. The ZnMgO oxide derived from a two-step annealing process shows excellent ultraviolet photodetection performance, with a responsivity of 1.48 A/W and a fast rise time of 0.32 s. This substrate-free and composition-controllable platform highlights a strategy for interface-driven synthesis of multimetallic MOFs and their derivatives for sensing and optoelectronic applications.