Hydrothermally synthesized SnO₂-graphene composites for H₂ sensing at low operating temperature

Graphical abstract: We synthesized the flower-like SnO₂ microspheres and SnO₂-graphene (S–G) composites with different GN contents through a simple one-pot hydrothermal method. The S–G composite with optimum GN contents exhibits the highest H₂ sensing response of 87.2 at 150 °C, which is about 70 times higher than that of pure SnO₂. - Highlights: • SnO₂-graphene (S–G) composites were synthesized by one-pot hydrothermal method. • Compared with pure SnO₂, S–G composites display much better H₂ sensing performance. • The excellent H₂ sensing performance was obtained at low operating temperature of 150 °C. • H₂ sensing mechanisms of S–G composites have been discussed in view of resistance change. - Abstract: The flower-like SnO₂ and a series of SnO₂-graphene (S–G) composites have been synthesized through a simple one-pot hydrothermal method. The as-prepared products were characterized by XRD, FESEM, TEM, BET, XPS, and Raman spectroscopy. The results clearly revealed that the three-dimensional flower-like SnO₂ hierarchical structure was destroyed by graphene nanosheets. The possible growth models for flower-like SnO₂ and S–G composites were proposed based on the microstructure characterizations. Furthermore, the H₂ sensing responses of all samples were investigated at low operating temperatures (OT) between 30 and 180 °C. The results indicate that the S–G-2-based sensor exhibits the excellent H₂ sensing response of 87.2 at a relatively low OT of 150 °C, which is about 70 times higher than that of pure SnO₂. Mechanism of H₂ sensing of S–G composite has been discussed in terms of resistance change, which is influenced by the Schottky barrier at the interface of S–G composites.