Pt decoration and oxygen defects synergistically boosted xylene sensing performance of polycrystalline SnO2 nanosheet assembled microflowers

Hierarchical SnO2 microflowers assembled by polycrystalline nanosheets were successfully synthesized through a hydrothermal method and then decorated with Pt nanoparticles via a facile deposition-calcination process. The structure, morphology, chemical component, specific surface area, surface defect, optical bandgap, and work function of pure SnO2 and Pt/SnO2 nanosheets were characterized, respectively. Compared with pure SnO2, increased oxygen defects and Fermi level were confirmed for Pt/SnO2 nanosheets. Taking xylene as a target molecule, gas sensing properties of both pure SnO2 and Pt/SnO2 were systematically investigated. Clearly, gas sensors based on these Pt/SnO2 nanosheets revealed lower optimum operating temperature (200 °C) than that of pure SnO2 (260 °C). In particular, the optimal Pt capacity of 0.5% in atomic ratio (named as 0.5% Pt/SnO2) exhibited the higher response value (Sr = 154.0) to 200 ppm xylene at 200 ℃ that is nearly 90 times higher than that of pure SnO2 (Sr = 1.7), and the shorter response/recovery time (29 s and 47 s) than that of pure SnO2 (124 s and 249 s). The excellent xylene sensing performance is mainly attributed to the unique hierarchical structure, abundant oxygen defects, as well as Pt-decoration induced chemical and electronic sensitization.