MCNTs/ZnO nanocomposite-fabricated nanosensor for 1-naphthyleacetic acid electroanalysis and its applications

Zinc oxide nanoparticles and multiwalled carbon nanotubes were mixed to create a novel carbon paste electrode known as MCNTs/ZnO/CPE—a substance that stimulates plant growth. This electrode was designed to investigate the effects of NAA. Various techniques, including cyclic voltammetry (CV) and square wave voltammetry (SWV), were employed to assess the stability and electrochemical properties of the MCNTs/ZnO/CPE electrode. The study aimed to examine the electrochemical behavior of NAA on MCNTs/ZnO/CPE to investigate its potential application in plant development. The experiment results provided valuable insights into the complementary effects of NAA and the electrode materials, paving the way for future advances in plant bioelectrochemistry. At a pH of 3.0, the more significant peak current indicates the effective electron transfer between the PB solution and the MCNTs/ZnO/CPE sensor. The sensor's outstanding catalytic activity at this pH further suggests its potential for various electrochemical applications. Actual samples, such as water, fruits, vegetables, and soil, were analyzed using the SWV method. ZnO/CPE, bare CPE, MCNTs/CPE, and MCNTs/ZnO/CPE all had peak currents of 4.044 µA, 10.40 µA, 12.91 µA, and 16.52 µA, respectively. The peak potentials for bare CPE, ZnO/CPE, MCNTs/CPE, and MCNTs/ZnO/CPE were all found to be 1.19 V, 1.19 V, 1.18 V, and 1.15 V, respectively. All the experiments were carried out at 25 s of optimum accumulation time. The detection limit was determined to be 1.1 nM, and the linear range is 0.2 × 10−8 to 7.0 × 10−6 M. The surface area of the unmodified CPE was determined to be 0.04 cm2, whereas the surface area of the modified CPE was determined to be 0.13 cm2. The mean value of the rate constant (ks) for the anodic reaction was 2.8 × 10−3 cm s−1. In addition to electro-kinetic factors like the effect of temperature and the heterogeneous rate constant, the electro-oxidation of NAA was examined about several parameters, including electron contribution, accumulation duration, pH, energy of activation, scan rate, and transfer coefficient.