Facile fabrication of HKUST-1 thin films and free-standing MWCNT/HKUST-1 film using a spray-assisted method

In this study, HKUST-1 (Cu-3(BTC)(2); BTC3 = 1,3,5-benzenetricarboxylate) thin films are fabricated by a new spray-assisted process that involves spraying of an HKUST-1 precursor solution through a two-fluid nozzle on heated substrates. The HKUST-1 films were fabricated in less than 3 min on various substrates, such as a Si(100) wafer, a glass plate, and porous alumina. The spray-assisted film fabrication process involves two steps: 1) formation of the nanoparticles from the droplets attached to the substrate surface during initial spraying (in 1 s) that act as seed particles, and 2) growth of seed particles by attaching additional droplets to form thin films. Furthermore, by adding multi-walled carbon nanotubes (MWCNTs) to the spraying solution, the HKUST-1 film formed by incorporating MWCNTs (MWCNT/HKUST-1 film) was fabricated in a facile manner. The MWCNT/HKUST-1 film can be peeled off to yield a free-standing film. The porosities of the HKUST-1 and MWCNT/HKUST-1 films are consistent with those of the HKUST-1 powders synthesized by a conventional batch process and a spray-assisted synthesis method.