Quasi Solid–Liquid Reaction Strategy to In Situ Synthesize the Conductive MOF Film with Ordered Submicron Macropores for Gas Sensing

A quasi solid–liquid reaction strategy is proposed that is based on the instantaneous transformation of structured solid ligand aggregation into insoluble Cu 3 (HITP) 2 metal–organic framework (MOF) aggregation without morphologic change (HITP = 2,3,6,7,10,11-hexaiminotriphenylene). The initial 3D ordered submicron macropores (TOM) in ligand aggregation can be maintained during the transformation due to the extremely rapid rate of coordination reaction. In this case, the in situ synthesis of the Cu 3 (HITP) 2 MOF film with large-scale TOM structure (TOM-Cu 3 (HITP) 2 film) on ceramic-based gold interdigital electrode (IDE) is achieved. Scanning electron microscope is used to confirm the morphology in each stage of synthetic process. Spectroscopic characterizations prove that there is no essential difference between TOM-Cu 3 (HITP) 2 film and ordinary Cu 3 (HITP) 2 MOF, except for slight differences in the contents of individual surface functional group and integral crystallinities, respectively. Notably, TOM structure endows the TOM-Cu 3 (HITP) 2 film with a dramatic promotion in sensitivity to H 2 S gas. The resistive response of the IDE loaded with TOM-Cu 3 (HITP) 2 film to the 80 ppm H 2 S gas reaches 78.5 at room temperature, which is 6.7× more than that of the Cu 3 (HITP) 2 film without TOM structure. The method of obvious universality allows the authors to perform in situ synthesis directly on the desired substrate without transfer process.