ZnO-CuO Hollow Nanocages Derived from Metal–Organic Frameworks for Selective H₂S Sensing

Metal–organic frameworks (MOFs) are considered potential materials in the gas sensor field because of their extremely porous, adjustable characteristics and high surface area. In this paper, based on a ZIF-8 precursor, ZnO-CuO hollow nanocage heterostructure materials were successfully fabricated by a multistep method, and the prepared ZnO-CuO sensor exhibited excellent respond to H2S. We found that when the mass ratio of CuO reaches 1 wt %, the response to 10 ppm hydrogen sulfide (H2S) was as high as 70, and the recovery time was 55 s at a low temperature of 115 °C. Such a ZnO-CuO sensor has a highly selective response to H2S gas. In addition, the lower detection limit can reach 200 ppb. Furthermore, the gas sensors also had high consistency and repeatability. Gas sensing mechanism studies have shown that the special nanocage structure with larger specific surface area helps to increase gas adsorption and diffusion on the surface of sensing materials, and the formation of p–n heterostructures by the introduction of CuO improves the sensitive and selective response to H2S. This work will improve the practical application of H2S gas sensors for their simple preparation method and research into the response mechanism.