Highly Sensitive Detection of Formaldehyde by Laser-Induced\nGraphene-Coated Silver Nanoparticles Electrochemical Sensing Electrodes

Abstract

Formaldehyde\n(HCHO) poses a grave threat to human health because\nof its toxicity, but its accurate, sensitive, and rapid detection\nin aqueous solutions remains a major challenge. This study proposes\na novel electrochemical sensor composed of a graphene-based electrode\nthat is prepared via laser induction technology. The precursor material,\npolyimide, is modified via the metal ion exchange method, and the\ndetective electrode is coated with graphene and silver nanoparticles.\nAnd the special structure of graphene-coated Ag was demonstrated using\nscanning electron microscopy (SEM) and high-resolution transmission\nelectron microscopy (HRTEM), and X-ray diffraction (XRD), Fourier\ntransform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS)\nresults show that graphene provides more sites for Ag NRs to be exposed\nand increases the surface area of contact between the solution and\nthe detection object. In addition, differential pulse voltammetry\n(DPV) analysis exhibits high linearity over the HCHO concentration\nrange from 0.05 to 5 μg/mL, with a detection limit of 0.011\nμg/mL (S/N = 3). The Ag NPs in the electrochemical reaction\nwill adsorb the intermediate ^•CO and ^•OH, catalyze their combination, and finally convert to CO₂ and H₂O, respectively. A microdetection device, specially\ndesigned for use with commercial micro-workstations, is employed to\nfully demonstrate the practical application of the electrode, which\npaves a way for developing formaldehyde electrochemical sensors.