Synthesis, Characterization, and gas sensing of CuO nanomaterials

Abstract:

Introduction:
Copper oxide (CuO) nanomaterials have garnered significant attention due to their unique structural, optical, and electrical properties, making them highly suitable for gas sensing applications. As a p-type semiconductor with a narrow band gap, CuO exhibits strong sensitivity and selectivity toward various toxic and combustible gases, including hydrogen sulfide (H₂S), carbon monoxide (CO), and ammonia (NH₃). The present study focuses on the synthesis, characterization, and gas sensing performance of CuO nanomaterials fabricated via a simple and cost-effective route.

Methods:
CuO nanomaterials were synthesized using a sol-gel method followed by calcination at controlled temperatures. Structural and morphological characteristics were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). Optical properties were examined through UV–Vis spectroscopy. Gas sensing performance was evaluated in a custom-built chamber using different concentrations of target gases at varying operating temperatures.

Results:
XRD analysis confirmed the formation of monoclinic-phase CuO with high crystallinity. SEM and TEM images revealed the nanostructured nature of the materials, displaying spherical and rod-like morphologies depending on synthesis conditions. UV–Vis spectra indicated strong absorption in the visible region with an estimated band gap of ~1.8 eV. Gas sensing studies demonstrated high sensitivity, rapid response and recovery times, and good selectivity toward H₂S at an optimal operating temperature of 200°C. The sensor also showed stable performance over multiple cycles and good repeatability.

Conclusions:
The synthesized CuO nanomaterials exhibit promising potential as gas sensors due to their favorable structural and sensing properties. These findings underscore the suitability of CuO-based nanostructures for real-time environmental monitoring and industrial safety applications.