Novel sea urchin-like hollow core–shell SnO2 superstructures: Facile synthesis and excellent ethanol sensing performance

Novel hierarchical sea urchin-like hollow core–shell SnO2 superstructures have been fabricated by a template-free hydrothermal method, based on an inside-out Ostwald ripening mechanism. For comparison, hollow SnO2 spheres were also prepared. It is found that the sea urchin-like hollow core–shell SnO2 superstructures exhibit nearly three times better response to ethanol than the hollow SnO2 spheres. The superior sensing performance is plausibly originated from the unique hierarchical core–shell structure with the nano-sized spikes (5–15 nm in diameter) on the shells.