Fabrication of metal–organic framework membranes using solid metal precursors for separation application

Metal-organic framework (MOF) membranes are attractive for a variety of industrial separation applications. Fabrication of crack/void-free MOF layers that bind tightly to the porous supports is one of the preconditions to achieve optimal performance of MOF membranes. Different from traditional metal salt solution-based precursors, solid metal precursors significantly improved the membrane quality not only by promoting the formation of crack/void-free MOF layers by modulating the MOF crystal nucleation and confining its further growth but also by enhancing the adhesion between MOF layers and porous supports. Besides, using solid metal precursors, MOF membranes can be fabricated in an eco-friendly solvent-free way, and different kinds of guest components can be encapsulated into MOF membranes to expand their application fields. Hence, this review aims to give an overview of the MOF membrane fabricated using different insoluble solid matter (including metal, metal oxide, metal hydroxide, and metal carbonate hydroxide) as metal precursors. Meanwhile, the application of MOF membrane in (gas, ion, oil/water, and other molecules) separation is summarized. Furthermore, opportunities and challenges in the MOF membrane fabricated using solid metal precursors are presented to give insightful guidance on the fabrication of next-generation high-performance membranes.