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This paper reported a simple template-free route to prepare hierarchical SnO2 nanostructures with hollow interiors. These high porous architectures, with the diameter about 200 nm, were assembled by nanosheets. Time-dependent experiments illustrated that these hierarchical and hollow nanostructures were transformed from solid SnO2 spheres composed of nanoparticles. Furthermore, the hierarchical SnO2 manifested high capacities and excellent cycle performances as the anode materials for lithium ion batteries, which can deliver a reversible capacity of 545 mA h g−1 up to 50 cycles. Even at high rates, the electrode exhibited excellent properties; the reversible capacities were about 590 and 460 mA h g−1 at the rate of 1.6 and 10 C. The improved electrochemical properties could be ascribed to the large surface area, enhanced structure stability, and short diffusion length for both lithium ion and electron.

The authors report on gas sensing properties of SnO2 hollow spheres with diverse microstructures, which are synthesized through controlled precipitation of Sn(OH)4 layers on carbon sphere templates, followed by heat treatment at different temperatures. Hollow spheres derived at 973 K consist of monolayer SnO2 grains, which lead to a huge activated surface area. The sensitivity of sensors based on SnO2 monolayer hollow spheres is up to 51 at 100 ppm ethanol, which is much higher than that of two other samples. We attribute this enhancement mostly to the enhanced depletion effect arising from the increased exposed surface. Our results suggest a direction for improving the performance of gas sensors by using monolayer porous hollow spheres.