Plasma-Treated Polyimide Film Modified by Liquid Epitaxially Grown HKUST-1 MOFs for Sensing Application

Metal-organic framework (MOFs) materials have the potential to be used in electrochemical sensors thanks to their porous nature, high surface area, and periodic lattice structures. However, the insulating nature of pristine MOFs is one of the drawbacks that limit their applicability in electrochemical sensors. Several works have proposed their integration with carbon nanomaterials to enhance the conductivity. On the other hand, Laser-induced graphene (LIG) is a one-step method to fabricate conductive graphene-based electrodes on flexible substrates such as Kapton. In this regard, this research proposes a novel methodology to fabricate surface-mounted MOFs (SURMOF) and LIG-based composite electrodes on Kapton. The Kapton sheet is modified with HKUST-1 MOF by alternative immersions in precursor solutions to achieve layer-by-layer (LbL) deposition and growth. Hence, Kapton is pre-treated with plasma to enhance the hydrophilicity by introducing oxygen functional groups on the surface which was confirmed with contact angle measurements. Different precursor materials were investigated for the LBL growth of HKUST-1. The obtained SURMOF on Kapton was characterized by spectroscopic methods. Finally, UV laser interaction with HKUST-1-modified Kapton led to the formation of LIG. The electrochemical performance of LIG on modified Kapton was compared with bare LIG. The proposed methodology is promising to realize flexible, easy-to-fabricate LIG-MOF'S electrodes for electrochemical sensors.