New Insight into the Gas Sensing Properties of CuOx Nanowires by Near Ambient Pressure XPS

This article presents an investigation of the sensing properties of chemiresistors based on Cu2O/CuO core-shell nanowires containing p - p´ heterojunctions. The nanowires were synthesized by a conventional hydrothermal method and used for the detection of ethanol and nitrogen dioxide, reducing and oxidizing agents, respectively. To unravel the chemical processes connected with gas detection, an in-situ approach was applied. This approach was based on Near Ambient Pressure X-ray Photoelectron Spectroscopy combined with simultaneous monitoring of sensor responses. The in-situ measurements were performed during exposure to the analytes at a total pressure of 0.05 – 1.05 mbar and 450 K, and were correlated with chemiresistor response measurements carried out at a standard pressure and under an ambient atmosphere. The study revealed that heterojunction treatment with ethanol vapours, accompanied by partial reduction of the nanowires, is the key step to obtaining chemiresistors with good sensing performance. Wh...