Dynamic Water-Driven Competitive Strategy Enables Selective and Easily Regenerable C₂H₂/C₂H₄ Separation on Gallate-Based Metal–Organic Framework Nanostructures

Efficient separation of C2 hydrocarbons remains a significant challenge in the petrochemical industry. Metal–organic framework nanostructures, with their tunable pore environments and exposed nanoscale metal sites, have shown great promise in enhancing π-electron gas separation. However, balancing molecular adsorption strength with desorption energy consumption continues to be a major challenge. In our previous work, we discovered that the gallate-based metal–organic framework nanostructure compounds exhibit selective adsorption of C2H4 through π-electron-induced local reconstruction. Building on this, we have proposed a ″dynamic water molecule-driven competition″ strategy in this study, in which the introduction of water molecules enables dynamic regulation of gas binding at the active metal sites. By leveraging the differential responses of M-gallate (Co, Ni, Mg) to various gas molecules, we achieved high-efficiency C2 separation and low-energy regeneration under dynamic adsorption–desorption competition modulated by water molecules. Experimental results, supported by DFT simulations, reveal that water molecules act as molecular modulators, reversibly competing with π-electron gases for binding near metal centers. This nanostructure-level competition mechanism significantly enhances gas separation performance and material recyclability. The ″dynamic water molecule-driven competition″ strategy proposed in this study not only opens up directions for the design of π-bonded gas separation materials but also provides an important technical reference for greening and decarbonizing industrial adsorption processes.