Synthesis of cuprous oxide nanoparticles by electrochemical method and evaluation of the corresponding nanoparticle film for humidity sensing

Cuprous oxide (Cu2O) nanoparticles with size of about 32 nm are synthesized via electrochemical method in NaCl solution with copper electrodes and K2Cr2O7 as an additive. Different techniques such as scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), x-ray Diffraction (XRD), transmission electron microscopy (TEM) and electron spectroscopy for chemical analysis (ESCA) are used for sample characterization. A universal miniature furnace is designed and developed for gas sensing application. It is made with alumina (Al2O3) tube with 0.5 mm inner diameter, 1mm outer diameter and 1 cm length and has capacity to reach up to 3500C. Calibration of bed/furnace is done with Keithley 240°C source meter with Lab tracer 2.0 software. Cu2O nanoparticle coating (thickness around 10 microns) is formed on the surface of the miniature alumina furnace, with thin platinum wire used as electrode. The current Vs. % RH of P type Cu2O exhibits linear change in current from 3.83 × 10⁻⁷ to 2.62 ×10⁻⁷ Amps for a relative humidity change from 11 to 84 % RH, respectively.