ZIF-8 Films Prepared by Femtosecond Pulsed-Laser Deposition

As metal–organic frameworks (MOFs) are coming of age, processing strategies and morphology engineering have gained considerable importance, given the need of thin film geometries for many applications. Using the femtosecond pulsed-laser deposition (femto-PLD) technique, we have fabricated films of the zeolitic imidazolate framework (ZIF) zinc 2-methylimidazolate (ZIF-8) for the first time, thus extending the available film fabrication techniques for MOFs to physical vapor deposition. While deposition of pristine ZIF-8 turned out to be unsuccessful, we demonstrate that hybrid ZIF-8 impregnated with polyethylene glycol 400 as a “vehicle” ablate under ultrahigh vacuum conditions to form films with approximate composition Zn(C3N2H2–CH3)2·1/6PEG-400. By washing the films with ethanol, the polyethylene glycol (PEG) additive can be removed, leading to pure ZIF-8 films on sapphire substrates. The target films and powders were comprehensively characterized by diffraction, spectroscopic and microscopic techniques as well as thermogravimetry and Ar physisorption measurements.