Design of Ag modified Cu@Cu₂O/CuO hierarchical heterostructure hybrid for high-performance room temperature NO₂ sensing

Room temperature (RT) NO₂ sensing has always been a challenge for metal oxide semiconductor gas sensors. Herein, we report a one-dimensional (1D) hierarchical Ag modified Cu@Cu₂O/CuO hybrid which is synthesized by low-temperature liquid-phase etching self-assembly method. The Ag nanoparticles are directly modified onto the surface of Cu nanowires (NWs) through simple and efficient substitution reaction, and serve as active centers to improve the gas sensing properties of the hybrid. Subsequently, the Ag–Cu NWs is etched by alkaline solution to form the 1D hierarchical Ag–Cu@Cu₂O/CuO hybrids at RT. When applied as sensing material, the Ag–Cu@Cu₂O/CuO exhibits high response of 71.3 to 10 ppm NO₂ with excellent selectivity and fast response/recovery at 25 °C. The nanostructure of the material is characterized systematically and the sensing mechanism is discussed. The synergistic effect of Ag heteroatom and the special morphology as well as the hierarchical Cu₂O/CuO heterostructure in the Ag–Cu@Cu₂O/CuO (4 h) hybrid are recognized as the main reason for its excellent NO₂ sensing performance. This work provides a good idea for simple and effective improving the gas sensing properties of metal oxide materials with low power consumption.