Gadolinium Oxide Nanorods Anchored on g-C3N4 Nanosheets for Dual-Mode Electrochemical Determination of Clioquinol in Real-Time Analysis

We present an inexpensive fabrication method in preparing one-dimensional gadolinium oxide (GdO) nanorods through hydrothermal synthesis and graphitic carbon nitride–g-C3N4, by a rapid calcination process. X-ray diffraction (XRD) patterns of GdO nanorods displayed a cubic crystal phase with an average crystalline size of 5–6.2 nm. Through high-resolution transmission electron microscopy micrographs, GdO exhibited a diameter of ∼20 nm. The GdO nanorods/g-C3N4 nanocomposite was analyzed using XRD, Fourier transmission-infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, field-emission scanning electron microscopy with elemental mapping, and energy-dispersive X-ray spectrometry. The GdO/g-C3N4 nanocomposite was fabricated on a screen-printed carbon paste electrode for the electrochemical determination of clioquinol, which demonstrated rapid electron and ion transfer. The sensor was studied for its dual-modality detection using differential pulse voltammetry (DPV) and amperometry (i–t) techniques, which showed a wide detection range for DPV from 0.099 to 448.30 μM and i–t from 0.008 to 78.7 μM, and the lateral limit of detection for DPV was 4.8 nM and i–t was 1.2 nM with ultra-low sensitivity for DPV of 16.39 μA μM–1 cm–2 and i–t of 15.6 μA μM–1 cm–2 (S/N = 3). The prepared electrochemical sensor exhibited stability, selectivity, and sensitivity, which were markedly reported by DPV and i–t tests, and its use was further studied in real-time analysis using pharmaceutical and biological samples.