N-doped carbon quantum dots @ hexagonal porous copper oxide decorated multiwall carbon nanotubes: A hybrid composite material for an efficient ultra-sensitive determination of caffeic acid

Abstract Herein, we report the nitrogen-doped carbon quantum dots (N-CQD) loaded hexagonal structured porous copper oxide (N-CQD/HP-Cu 2 O) composite for the first time. The composite was synthesized using a facile hydrothermal approach. The loading of N-CQD in N-CQD/HP-Cu 2 O composite plays a vital role in the structural formation, and the composite has been evaluated using Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron, and transmission electron microscopy. Hereafter, the composite was anchored with multiwall carbon nanotube (MWCNT) using ultrasonication method to construct the N-CQD/HP-Cu 2 O/MWCNT hybrid composite material and used as an electrode material for effective electrochemical detection of caffeic acid (CA). The sensing behaviour was examined using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. As a result, the developed N-CQD/HP-Cu 2 O/MWCNT/GCE sensor exhibits a lower detection limit of 0.004 μM and excellent sensitivity of 31.85 μA μM −1  cm −2 for the detection of CA. Thus, the hybrid composite could be a promising electrode modifier for the enhanced electrocatalytic applications. Finally, the developed sensor has applied for the detection of CA in red wine samples.