Surface Crystallization of Liquid Au-Si and Its Impact on Catalysis.

In situ transmission electron microscopy reveals that an atomically thin crystalline phase at the surface of liquid Au-Si is stable over an unexpectedly wide range of conditions. By measuring the surface structure as a function of liquid temperature and composition, a simple thermodynamic model is developed to explain the stability of the ordered phase. The presence of surface ordering plays a key role in the pathway by which the Au-Si eutectic solidifies and also dramatically affects the catalytic properties of the liquid, explaining the anomalously slow growth kinetics of Si nanowires at low temperature.

Enhanced, robust light-driven H generation by gallium-doped titania nanoparticles.

The splitting of water into molecular hydrogen and oxygen with the use of renewable solar energy is considered one of the most promising routes to yield sustainable fuel. Herein, we report the H evolution performance of gallium doped TiO photocatalysts with varying degrees of Ga dopant. The gallium(iii) ions induced significant changes in the structural, textural and electronic properties of TiO nanoparticles, resulting in remarkably enhanced photocatalytic activity and good stability for H production.

Nanoscale structural oscillations in perovskite oxides induced by oxygen evolution.

Understanding the interaction between water and oxides is critical for many technological applications, including energy storage, surface wetting/self-cleaning, photocatalysis and sensors. Here, we report observations of strong structural oscillations of BaSrCoFeO (BSCF) in the presence of both HO vapour and electron irradiation using environmental transmission electron microscopy. These oscillations are related to the formation and collapse of gaseous bubbles.

Tuning the Activity of Oxygen in LiNiCoAlO Battery Electrodes.

Layered transition metal oxides such as LiNiCo AlO (NCA) are highly desirable battery electrodes. However, these materials suffer from thermal runaway caused by deleterious oxygen loss and surface phase transitions when in highly overcharged and overheated conditions, prompting serious safety concerns. Using in situ environmental transmission electron microscopy techniques, we demonstrate that surface oxygen loss and structural changes in the highly overcharged NCA particles are suppressed by exposing them to an oxygen-rich environment.

Atomic Resolution in Situ Imaging of a Double-Bilayer Multistep Growth Mode in Gallium Nitride Nanowires.

We study the growth of GaN nanowires from liquid Au-Ga catalysts using environmental transmission electron microscopy. GaN wires grow in either ⟨112̅0⟩ or ⟨11̅00⟩ directions, by the addition of {11̅00} double bilayers via step flow with multiple steps. Step-train growth is not typically seen with liquid catalysts, and we suggest that it results from low step mobility related to the unusual double-height step structure.