Preparation of Au-sensitized 3D hollow SnO2 microspheres with an enhanced sensing performance

• A hollow microsphere was synthesized.
• The microsphere has a size of 600–900 nm.
• The microsphere exhibits excellent sensing performances.

A controlled synthesis of three-dimensional Au-sensitized SnO2 hollow microspheres that composed of numerous nanorod subunits has been realized via a facile one-pot hydrothermal method without employing any templates or capping agents. The structural and morphological characteristics of the pure and Au-loaded SnO2 microspheres are revealed by X-ray diffraction, field-emission scanning electron microscope, and high resolution transmission electron microscope, respectively. The characterized results reveal that SnO2 hollow microspheres have the diameter of 600–900 nm with a rutile structure, which are composed of high densities of secondary SnO2 nanorods with the size of 20–50 nm. Furthermore, the gas sensors based on the pure and Au-loaded SnO2 have been fabricated, and the Au-loaded hierarchical SnO2 hollow microspheres exhibit more excellent sensing performances than that of pure SnO2 to acetone. The response and recovery times of the Au-loaded SnO2 microspheres are 0.9 s and 21 s when the sensor is exposed to 5 ppm acetone at the optimal operating temperature of 220 °C. These improved acetone-sensing performances are attributed to the catalytic effect of Au and the enhanced electron depletion at the surface of SnO2 hollow microspheres.