Adsorption-Enhanced\nSensitivity for Electrochemical\nSensing of Diclofenac by Poly(ether sulfone)-Based Laser-Induced Graphene

Emerging contaminants are a matter of growing concern\nfor environmental\nand human health and safety, requiring efficient and affordable sensing\nplatforms. Laser-induced graphene (LIG) is a novel material with a\n3D porous graphene structure that can be fabricated in a simple one-step\nfabrication process. However, most LIG-based works in electrochemical\nsensors are limited to polyimide (PI)-based platforms, thus limiting\nthe purview of properties of LIG dependent on the substrate–laser\ninteraction. Diclofenac (DCF), a nonsteroidal anti-inflammatory drug,\nis an emerging contaminant in water and wastewater that threatens\naquatic and terrestrial life. Furthermore, LIG-based sensors have\nnot been used to sense DCF. In this work, we demonstrate the spontaneous\nadsorption behavior of LIG toward DCF without applying any external\npotential. This spontaneous adsorption phenomenon can enhance the\nsensitivity per the characteristics of the tested water samples and\npermissible standards to be followed. Poly(ether sulfone)-based LIG\n(PES-LIG) is found to be more responsive to laser irradiation than\nPI-LIG due to its highly porous surface and fibrous nature, imparting\nmore electrochemical sites and adsorption area for DCF. These characteristics\nlead to a higher sensitivity of 0.2774 μA μM<sup>–1</sup> toward DCF sensing for PES-LIG with a limit of detection of 0.1\nμM. The sensors were applied for DCF measurement in wastewater\nand tap water samples with appreciable selectivity. The specific adsorption\nbehavior of LIG toward DCF could pave the way for new pathways in\nemerging contaminant sensing and removal as well as for other applications.