In situ Synthesis of Single Layered Metal–Organic Frameworks via Inkjet Printing on a Cellulose Nanofiber Film

The inkjet printing is a simple method to develop pattern-controlled 2D metal-organic frameworks (MOFs) due to its cost-effectiveness and ease of operation. Despite the sophisticated structures of MOF crystals, the MOF surfaces are easily contaminated by the adsorption of an ink solution, and the printing nozzle can be clogged by the aggregates of MOFs during printing. Unlike the mixture inks of MOFs and a carrier medium, the surface-specific patterning by in situ synthesis provides the film surface with the controlled patterns of an MOF single layer having different morphologies of MOFs without changing the ink cartridges. It enables facile printing due to the low viscosity of inks and escapes the risk of nozzle clogging because MOFs are synthesized at the printed patterns on the substrates. The ion-exchanged cellulose nanofiber (CNF) films form strong coordination with metal ions enhancing the stability of the MOFs on the film surface. It also demonstrates the controlled coverage of the MOFs by the printing pass number and the carboxylate content of CNF and the tunable adsorption of the guest molecules for different loading capacities of the printed patterns.