Two-dimensional metal-organic frameworks and their derivatives: synthesis, 3D printing fabrication, and applications

Among metal-organic frameworks (MOFs), two-dimensional metal-organic frameworks (2D MOFs) own unique dimension-related properties, such as ultrathin structures, large surface areas, and more accessible active sites, which have been widely used in energy conversion and storage applications. Constructing 3D macroscopic structures of 2D MOFs is an effective approach to further enhance device performances by facilitating medium (e.g., ion, electron, and gas) transportation. 3D printing technology can design and build desired 3D macroscopic structures easily and quickly. This review summarizes recent advances in the 2D MOFs and their derivatives, focusing on their synthesis methods, 3D printing fabrication, and energy conversion and storage applications. Synthesis methods were first presented, including the top-down and bottom-up methods. 3D printing techniques for the fabrication of MOFs were then introduced, mainly including direct ink writing and inkjet printing. We further overview the energy conversion and storage applications of the 3D-printed 2D MOFs, such as lithium-ion batteries, lithium-sulfur batteries, supercapacitors, CO2 reduction reactions, oxygen evolution reactions, and oxygen reduction reactions. Finally, we concluded the current challenges and prospects for 2D MOFs and their 3D printing fabrications.