Catalysis-Assisted Synthesis of Two-Dimensional Conductive Metal–Organic Framework Films with Controllable Orientation

The facile preparation of two-dimensional (2D) conductive metal–organic framework (MOF) films with controllable orientation and thickness greatly facilitates the further structure–property investigation and performance optimization in their applications. Here, we report a catalysis-assisted synthesis strategy to the rapid production of oriented films of catechol-based (Cu 3 (HHTP) 2, Zn 3 (HHTP) 2, and Cu 2 TBA) and diamine-based (Ni 3 (HITP) 2 ) 2D conductive MOFs with thicknesses adjustable from tens of nanometers to several micrometers. Relying on the utilization of a 0.3 nm Pt layer, which can be conveniently predecorated on a substrate surface via evaporating deposition or sputtering, as a catalyst for the aerobic oxidation of the redox-active ligands to trigger the formation of 2D conductive MOFs, this strategy is compatible with a majority of commonly used substrates and capable of producing patterned films with feature sizes ranging from micrometers to centimeters. Investigation on the growth kinetics of Cu 3 (HHTP) 2 indicates that the preferential growth along the c -axis or in the ab -basal plane of its crystallites can be flexibly tuned by the formation reaction kinetics to guide the evolution of films with the face-on or edge-on orientation. The chemiresistive device incorporating the face-on Cu 3 (HHTP) 2 film presents a high response (197%) and a fast respond speed (27 s) toward NH 3 (30 ppm) at room temperature, which are superior not only to its edge-on counterpart (90% and 69 s, correspondingly) but also to other reported Cu 3 (HHTP) 2 -based sensors.