Enhanced H₂S gas-sensing performance of Zn₂SnO₄ hierarchical quasi-microspheres constructed from nanosheets and octahedra

Most of the reported ternary oxides based sensors have not been realized to detect ppb-level H₂S till now. In this work, Zn₂SnO₄ hierarchical quasi-microspheres were prepared through a facile surfactant-free hydrothermal method followed by calcination in air atmosphere. The quasi-microspheres are composed of nanosheets with the thickness of 100 nm and octahedra with the average size of 0.63 μm, respectively. The sensor fabricated from such Zn₂SnO₄ hierarchical quasi-microspheres shows excellent selective response to H₂S at 133 °C with the lowest detection limit of 1 ppb. The gas response exhibits good linear relationship in the concentration range of 1-1000 ppb. Such outstanding H₂S sensing property might be attributed to its porous structure, the synergistic effect of the two typical building blocks and the surface adsorbed oxygen, and the possible sensing mechanism is also discussed.