One-Step Hydrothermal Formation of Bi2O3 Nanourchins with Radially Ultrathin Nanotubes

A novel Bi 2 O 3 urchin-like microarchitecture with high-density radially oriented Bi 2 O 3 nanotubes (NTs) was fabricated by a one-step hydrothermal approach without any template or surfactant at a relative low temperature of 90 °C. The radial Bi 2 O 3 NTs on the surface of nanourchins (NUs) were 4–7 nm in diameter and ∼1.7 µm in length. The mean wall thickness of the NTs was as thin as 1.5 nm. Based on the time-dependent evolutions of morphology examined by scanning electron microscope (SEM), a “rolling-up mechanism” was demonstrated to explain the formation of the ultrathin Bi 2 O 3 NTs. The ultrathin and long NTs bring on the high surface-to-volume ratios of the Bi 2 O 3 urchin-like microarchitectures, which makes them great potential applications in gas sensors, photocatalysis, environmental purification, and solar energy conversion.