Assembly of hierarchical ZnSnO3 hollow microspheres from ultra-thin nanorods and the enhanced ethanol-sensing performances

ZnSnO3 hollow microspheres with a hierarchical structure composed of small nanorods as building blocks are synthesized by a facile one-pot hydrothermal method at 160 °C. The individual hierarchical ZnSnO3 microsphere ranges from 600 to 900 nm in diameter. The time-dependent hollowing evolution of ZnSnO3 microspheres reveals that the preferential formation of solid ZnSnO3 microspheres and the subsequent dissolution of the interiors to form hollow architectures are performed via Ostwald ripening. Moreover, ZnSnO3 spheres with hollow interiors and permeable surfaces are exploited as gas sensors, exhibiting improved sensing performances to ethanol. The response-recovery times of sensor based on these ZnSnO3 hollow microspheres are 0.9 and 2.2 s when the sensor is exposed in ethanol at the optimal operating temperature of 270 °C. The significant decrease in response-recovery times are attributed not only to the surface accessibility obtained by the hierarchical hollow architectures, but also to these rodlike building blocks with ultra-thin diameters.