On-Chip Template-Directed Conversion of Metal Hydroxides to Metal-Organic Framework Films with Enhanced Adhesion

Interfacial compatibility between metal-organic framework (MOF) films and the underlying substrates determines the integrity of MOF films and their associated functions, and thus it has been gaining growing attention. Herein, we present a comparison of adhesion properties at the chip level of two disparate nickel (Ni)-MOF films, respectively, obtained by direct hydro/solvothermal growth and template-directed conversion approaches. We demonstrate that the on-chip delamination/corrugation of the films obtained by the direct growth approach can be circumvented by adopting the template-directed approach, which enables delicate dissolution of primarily grown nanoflaked nickel hydroxide (Ni(OH)₂) films and thus triggers the controllable formation of Ni-MOF films. Successful on-chip conversions of Ni(OH)₂ layers to different Ni-MOF thin films with good homogeneity, compactness, and appreciable affinity to the substrates are verified by multiple microscopic and spectroscopic techniques. Notably, the resultant Ni-MOF films do not show delamination even after activation with additional treatments, such as solvent soaking, nitrogen (N₂) blowing for 1 h, and scotch-tape tests. As a demonstration of the application of MOF films, a Ni-NDC (NDC stands for 2,6-naphthalenedicarboxylate) MOF-coated sensor exhibits selective detection toward benzene vapor. This study highlights the importance of interfaces between MOF films and substrates and provides new perspectives for integrating MOF films onto microelectronic devices with robust adhesion for practical applications.