Electron-beam-induced growth of TiO₂ nanostructures

We report the evolution of titanium dioxide nanostructures when Au nanoparticles, supported on single crystal TiO₂ substrates, were heated under ∼260 Pa of flowing O₂ in an environmental transmission electron microscope. Nanostructures with different morphologies were first observed around 500°C. Our measurements show that temperature, oxygen pressure, and the electron beam control the nanostructure growth. We propose a reaction-controlled growth mechanism where mobile Ti atoms generated by the electron- beam-induced reduction of TiO2 are preferentially reoxidized at the Au-TiO₂ interface.