Paper-Like Writable Nanoparticle Network Sheets for Mask-Less MOF Patterning

Geometrical structuring of monolithic metal-organic frameworks (MOFs) components is required for their practical implementation in many areas, including electronic devices, gas storage/separation, catalysis, energy storage as well as bio-medical applications.
Despite progress in structuring MOFs, an approach for the precise patterning of MOFs functional geometries such as channels, wells and membranes in the millimeter- to micro-meter depth is lacking. Here, we report a facile and flexible concept for microfabrication of complex MOFs patterns on large surfaces. Our method relies on the engineering of easily-writable sheets
of precursor metal oxide nanoparticles that are loosely bonded to a supporting substrate and can be removed by low-power laser ablation, resulting in well-defined in-depth MOFs patterns. The gas-phase conversion of these patterned ceramic nanoparticle sheets results in monolithic MOFs objects with arbitrarily shaped geometries and thickness of up to hundreds of micrometers. We demonstrate the writing of complex patterns of Zeolitic Imidazolate Framework-8 (ZIF-8) by a variety of approaches including ion beam, laser and handheld writing with a pen. Sub-100 nm patterns were achieved by focused ion beam (FIB) among others.
Artless handwritings were obtained by using a pen in a similar fashion to writing on a paper. The pure ZIF-8 composition of the resulting patterns is confirmed by a series of physical and chemical characterization techniques, with a small laser-affected area near the patterned edge. This facile MOF precursor-writing approach provides novel opportunities for the design of MOF-based devices with applications ranging from micro-fluidics to renewable energy systems.