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

Cuprous oxide (Cu
2
O) nanoparticles with size of about 32 nm are synthesized via electrochemical method in NaCl solution with copper electrodes and K
2
Cr
2
O
7
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 (Al
2
O
3
) 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. Cu
2
O 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 Cu
2
O 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.