CuO nanoparticle loaded ZnO hierarchical heterostructure to boost H2S sensing with fast recovery

To achieve both sensitive and recoverable detection of H2S gas at low temperature, ZnO@CuO hierarchical heterostructures composed of porous hollow spheres array are in situ prepared through a template-assisted magnetron sputtering and subsequent annealing treatment. It was found that as the sputtering time of metal copper target is 40 s, the ZnO@CuO hierarchical heterostructure shows remarkably enhanced sensing response (Ra/Rg = 20.7) with short response/recovery time (33/298 s) toward 10 ppm (ppm) of H2S gas at a low operating temperature (25 ?C) compared with pristine ZnO and CuO sensing film. Such sensor exhibits a distinct response to an ultralow concentration of 20 parts per billion (ppb) H2S gas and possesses easy recovery even when the concentration of H2S gas increases to 100 ppm. Density functional theory (DFT) calculations reveal that H2S gas molecules tend to be adsorbed on the surface of ZnO@CuO hierarchical heterostructure compared with pristine ZnO. Moreover, the energy barrier for H2S decomposition on the heterostructure?s surface is 0.25 eV, indicating that this is a thermodynamically favorable reaction. Calculation and X-ray photoelectron spectroscopy analysis further revealed that the porous hierarchical heterostructure, p-n heterojunction at the interface, and intermediate CuS nanoparticles with small size are the major factors to enhance H2S gas sensing properties. Our work affords great potential for the development of high-performance gas sensors for H2S detection.

Automated summary

ZnO@CuO hierarchical heterostructures were prepared through template-assisted magnetron sputtering and annealing, showing sensitive and recoverable detection of H2S gas at low temperature. The structure exhibits enhanced sensing response and short response/recovery time, making it a promising platform for high-performance gas sensors.