Paper TF-TuA1
ALD ZnO for Rapid Synthesis of Cu-BTC MOF Thin Films and Patterns

Tuesday, October 20, 2015, 2:20 pm, Room 111

Metal-organic frameworks (MOFs) are crystalline porous materials that consist of metal ions/clusters and organic linkers. MOFs typically exhibit high surface area, good adsorption capacity and opportunity for post-synthetic modification. However, the insoluble MOF powders typically synthesized through conventional solvothermal methods may not be the ideal configuration for gas filters, chemical sensors and smart membranes etc. Growing MOF thin films onto various functional substrates, especially in a high-throughput process with low energy input, is therefore highly desired for MOF industrial implementation and new applications.

Here we report a rapid room-temperature synthesis route for Cu-BTC (Cu₃(BTC)₂) MOF thin films using ZnO nucleation layers deposited via atomic layer deposition (ALD). We find in just 1 minute of exposure to the Cu-BTC precursor solution, dense Cu-BTC thin films can be integrated onto various ALD ZnO coated substrates including silicon wafers, polymer spheres, and fibrous materials. MOF patterns can also be obtained on pre-patterned ZnO surfaces. The space-time-yield of the Cu-BTC production reaches up to 2.9×10⁴ kg∙m^-3∙d^-1, which is over 10× higher than previous reports. We further investigated the surface reactions between ALD ZnO and MOF precursor solutions using high-resolution EDX, XRD and FTIR. The results suggest hydroxyl double salt ((Zn,Cu)(OH)₃NO₃) is an important intermediate to drive the rapid formation of Cu-BTC thin films. Breakthrough tests were performed to demonstrate the high adsorption capacity of these MOF-functionalized materials for toxic industrial chemicals. This rapid room-temperature approach is also promising for new MOF-based composite materials for membrane separation, gas storage, chemical sensing and other applications.