Assembling SnO2 nanocubes to nanospheres for high-sensitivity sensors

► The small size nanospheres of diameter about 150 nm are synthesized. ► The modulations of quantum confinement and large contact area were realized. ► Numerous tetragonal nanoprims of 8 nm compose on the surface of nanospheres. ► The sensitivity could reach 53 to 50 ppm ethanol at a working temperature of 275 °C. ► Nanospheres are promising materials for ethanol gas sensors.