Studies on Sensing Properties and Mechanism of CuO Nanoparticles to H(2)S Gas

In this work, the high crystalline copper oxide (CuO) nanoparticles were fabricated by a hydrothermal method, and their structural properties were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The sensing results show that CuO nanoparticles exhibit enhanced sensitivity and good selectivity for hydrogen sulfide (H(2)S) gas at a low temperature. There are two working mechanisms involved in the H(2)S sensing based on CuO nanoparticle sensors. They are the H(2)S oxidation mechanism and the copper sulphide (CuS) formation mechanism, respectively. The two sensing mechanisms collectively enhance the sensor’s response in the H(2)S sensing process. The Cu–S bonding is stable and cannot break spontaneously at a low temperature. Therefore, the CuS formation inhibits the sensor’s recovery process. Such inhibition gradually enhances as the gas concentration increases from 0.2 ppm to 5 ppm, and it becomes weaker as the operating temperature rises from 40 °C to 250 °C. The XPS results confirmed the CuS formation phenomenon, and the micro Raman spectra demonstrated that the formation of CuS bonding and its decomposition can be effectively triggered by a thermal effect. Gas-sensing mechanism analysis supplied abundant cognition for the H(2)S sensing phenomena based on CuO materials.