Sulfur dioxide gas sensing at room temperature based on tin selenium/tin dioxide hybrid prepared via hydrothermal and surface oxidation treatment

In this paper, a novel SnSe/SnO2 nanoparticles (NPs) composite has been successfully fabricated through hydrothermal method and surface oxidation treatment. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). A series of morphological and structural characteristics confirm that the SnSe/SnO2 NPs composite shows a core–shell structure with a SnO2 shell with thickness of 6 nm. The prepared SnO2 NPs and SnSe/SnO2 NPs composite were applied as gas-sensing materials, and their gas-sensing properties were investigated at room temperature systematically. Experimental results show that the response value of the SnSe/SnO2 composite sensor toward 100 × 10–6 SO2 is 15.15%, which is 1.32 times higher than that of pristine SnSe (11.43%). And the SnSe/SnO2 composite sensor also has a detection limit as low as 74 × 10–9 and an ultra-fast response speed. The enhanced gas-sensing performance is attributed to the formation of p–n heterojunction between SnSe and SnO2 and the appropriate SnO2 shell thickness.