Rapid fabrication of partially exfoliated graphite foil with 3D hierarchical structure and its application in electrochemical detection of olaquindox

Abstract

An ultra-fast and controllable electrochemical method for preparation of partially exfoliated graphite foil (EG) was developed. The exfoliation process was realized in NaH 2 PO 4 aqueous by a multi potential step (STEP) technology. The EG electrode possesses a 3D hierarchical structure with the graphene-like nanosheets seamlessly linked with the graphite substrate. The EG electrode can be directly used as working electrode of electrochemical sensor. The performed sensor displayed high performance for electrochemical detection of olaquindox (OLA), with limit of detection (LOD) of 15 nM and a linear range of 0.05–18.0 μM. In this work, an ultra-fast (150 s) and controllable electrochemical method for preparation of partially exfoliated graphite foil (EG) was developed. The exfoliation process was realized in NaH 2 PO 4 aqueous by a multi potential step (STEP) technology. The graphite foil (G) was switched periodically between the mild oxidation potential and the reduction potential, avoiding completely exfoliation of the graphene sheets. The exfoliation degree of G electrode can be strictly controlled by the electrochemical parameters. The EG electrode possesses a hierarchical structure with the graphene-like nanosheets seamlessly linked with the graphite substrate, which can ensure its direct use as working electrodes for electrochemical sensors. Owing to its large surface area (6.1 times higher than G electrode), extremely low resistance ( R ct = 0.247 Ω), and promotion of adsorption of molecules, the EG electrode displayed surpassed catalytic effect toward the electrochemical redox of olaquindox (OLA). Based on the EG electrode, a high-performance electrochemical sensor for detection of OLA was constructed. The limit of detection (LOD) of the proposed sensor was achieved to be 15 nM (S/N=3), with a linear range of 0.05 – 18.0 μM and ultra-high sensitivity of 2.94 × 10 −3 A cm −2 μM −1 . Further, the low cost, flexible, small volume and easy integration make the EG electrode based sensor promise perspectives in the field of electroanalysis.