Photochemical Fabrication of Ag‐Modified Hierarchical Cu@Cu₂O/CuO Nanocomposite Toward Room Temperature NO₂ Detection

Developing room temperature (RT) gas sensor based on metal oxide semiconductor material has long been challenging. Herein, a 1D hierarchical Ag‐modified Cu@Cu 2 O/CuO nanocomposite has been designed by low‐temperature etching self‐assembly combined with photochemical deposition method based on Cu nanowires (NWs). After a step of alkaline solution etching, the surface of Cu NWs is self‐assembled to form a hierarchical Cu@Cu 2 O/CuO, and then Ag nanoparticles are modified on its surface by photochemical deposition to obtain the desired material. All the preparation processes are carried out at RT and have good controllability. When applied as sensing material, the optimal Cu@Cu 2 O/CuO/Ag nanocomposite exhibits high response of ≈337.0 to 10 ppm NO 2 with excellent selectivity and fast response/recovery (60/400 s) at 25 °C. It is worth noting that such a strategy of loading Ag nanoparticles improves its gas sensitivity by about 42.4 times, and the resulting sensor shows good sensitivity and screening ability to NO 2 in the low concentration range. Finally, the nanostructure of the material is characterized systematically and the sensing mechanism is discussed.