Multilevel Heterostructure CNT-CuO-ZnO Film for Sensitive H₂S Detection

The severe hazards posed by H2S gas, including brain/respiratory damage, poisoning risks, and environmental pollution issues, have posed an urgent need for developing efficient, real-time flexible room-temperature gas sensors. Here, we loaded CuO-ZnO onto carbon nanotube (CNT) films through a solvothermal method to form a multilevel CNT-CuO-ZnO film, which retained the two-dimensional network of CNTs and the crystal structure of metal oxide particles. CuO and ZnO nanoparticles were wrapped around the surface of CNT bundles, in contact with each other, agglomerated into nanoclusters, and were connected in series on CNTs to form a rough surface coaxial bundle. The response to 300 ppb H2S was 50%, which was higher than that of the pure CNT film (4.7%), and after bending, the response to H2S remained almost unchanged (96.8%). The measured limit of detection of the CNT-CuO-ZnO film was 20 ppb (2%).