Mass transport control over a conductive MOF 3D thin film to improve gas sensing

Abstract

Mass transport in a c-MOF thin film has a significant impact on various chemical applications. However, a systematic study of the influence of the microstructure of c-MOF thin films on mass transport has not yet been conducted. In this work, a finite element method simulation model was used to explore the influence of the microstructure of a MOF 3D thin film on mass transport, with the aim of improving the performance of MOF thin films applied in heterogeneous reactions. The model reveals the relationship between the morphology-induced effective diffusion area and mass transfer efficiency in the film. As a proof of concept for the simulation model, Cu-HHTP was coated on ZnO-NWAs to form 3D thin films with different microstructures and their NH₃ sensing performance was evaluated. The results show that the Cu-HHTP 3D thin film with a thickness of ∼20 nm, a height of ∼3 μm and a density of 85% exhibits the highest response. This is attributed to the optimal effective diffusion area provided by this microstructure to improve the mass transfer efficiency in the 3D thin film, which aligns well with the theoretical model. This work opens an avenue for designing high-performance MOF 3D thin films for heterogeneous reactions.