Metal-organic frameworks (MOFs) have garnered widespread attention due to their inherent tunability and consequent applications for a variety of technologies. Spin-coating is a fast and cost-effective method for new materials discovery, which yields less chemical waste than traditional solvothermal, dip-coating, or other layer-by-layer synthesis methods. The purpose of this work is to expand the types of supported MOF thin films to include a bimetallic thin film and to understand the effects of temperature on the MOF size and coverage, as well as the ranges and limits of composition. Because the pillared MOF archetype M2(BDC)2DABCO, where (M = Cu2+, Zn2+), is known to exist as copper and zinc MOF analogues; therefore, it was chosen for incorporating both metals into a single structure. For the thin films, MOF growth increased with temperature until solution instability (>52 °C). Thin films are sensitive to metal precursor selection; the Zn-MOF thin film would not grow using Zn(NO3)2 as the precursor; however, Zn(OAc)2 resulted in the cogrowth of ZnO nanoparticles within the MOF. The amount of Zn2+ incorporated into the Cu-MOF can be changed by altering volume ratios between Cu(NO3)2 and Zn(NO3)2 precursors in solution. Understanding these parameters for a bimetallic MOF thin film provides a flexible methodology for surface-mounted thin films for future discovery and advancement.
Ralph et al. (Fri,) studied this question.