Development of Methanol Sensor Based on Sol-Gel Drop-Coating Co3O4•CdO•ZnO Nanoparticles Modified Gold-Coated μ-Chip by Electro-Oxidation Process

Herein, novel Co3O4 center dot CdO center dot ZnO-based tri-metallic oxide nanoparticles (CCZ) were synthesized by a simple solution method in basic phase. We have used Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscope (FESEM), Dynamic Light Scattering (DLS), Tunneling Electron Microscopy (TEM), and Energy-Dispersive Spectroscopy (EDS) techniques to characterize the CCZ nanoparticles. XRD, TEM, DLS, and FESEM investigations have confirmed the tri-metallic nanoparticles' structure, while XPS and EDS analyses have shown the elemental compositions of the CCZ nanoparticles. Later, a Au/mu-Chip was modified with the CCZ nanoparticles using a conducting binder, PEDOT: PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) in a sol-gel system, and dried completely in air. Then, the CCZ/Au/mu-Chip sensor was used to detect methanol (MeOH) in phosphate buffer solution (PBS). Outstanding sensing performance was achieved for the CCZ/Au/mu-Chip sensor, such as excellent sensitivity (1.3842 mu A mu M(-1)cm(-2)), a wide linear dynamic range of 1.0 nM-2.0 mM (R-2 = 0.9992), an ultra-low detection limit (32.8 +/- 0.1 pM at S/N = 3), a fast response time (~11 s), and excellent reproducibility and repeatability. This CCZ/Au/mu-Chip sensor was further applied with appropriate quantification results in real environmental sample analyses.

Automated summary

Novel tri-metallic oxide nanoparticles CCZ were successfully synthesized and characterized. The modified sensor showed outstanding performance in detecting methanol, with excellent sensitivity, wide linear dynamic range, ultra-low detection limit, fast response time, and great reproducibility and repeatability. The sensor was further applied in real environmental sample analysis with satisfactory quantification results.