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

Abstract

• CuO nanoparticle loaded ZnO hierarchical heterostructure were in situ synthesized through a facile method. • The sensor based on the ZnO@CuO-40 exhibited excellent sensing performance with a detection limit of 20 ppb H 2 S at a low temperature (25 °C). • The enhanced sensing mechanism of the ZnO@CuO hierarchical heterostructure toward H 2 S was proposed based on the DFT Calculation and quasi in-situ XPS analysis. To achieve both sensitive and recoverable detection of H 2 S 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 (R a /R g = 20.7) with short response/recovery time (33/298 s) toward 10 ppm (ppm) of H 2 S 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) H 2 S gas and possesses easy recovery even when the concentration of H 2 S gas increases to 100 ppm. Density functional theory (DFT) calculations reveal that H 2 S gas molecules tend to be adsorbed on the surface of ZnO@CuO hierarchical heterostructure compared with pristine ZnO. Moreover, the energy barrier for H 2 S 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 H 2 S gas sensing properties. Our work affords great potential for the development of high-performance gas sensors for H 2 S detection.