Transparent 'solution' of ultrathin magnesium hydroxide nanocrystals for flexible and transparent nanocomposite films

Surfactant-Free Aqueous Dispersions of Shape- and Size-Controlled Zirconia Colloidal Nanocrystal Clusters with Enhanced Photocatalytic Activity

Colloidal nanocrystal clusters (CNCs) are formed by clustering nanocrystals into secondary structures, which represent a new class of materials and have attracted considerable attention, owing to their unique collective properties and novel functionalities achieved from the ensembles in addition to the properties of each individual subunit. Here, we design a simple route to prepare aqueous dispersions of highly stable ZrO₂ CNCs with tunable shape and size without modification. ZrO₂ CNCs are composed of many ZrO₂ nanocrystals each with a size of about 7 nm and possess a mesoporous structure. Both cube-like and star-like shapes of CNCs can be achieved by using different alkaline sources, while the size of CNCs can be adjusted by changing the hydrothermal time. The as-prepared aqueous dispersions of ZrO₂ CNCs display an enhanced photocatalytic activity in the degradation of rhodamine B (RhB), compared with ZrO₂ nanodispersions. More interestingly, star-like ZrO₂ CNCs show better photocatalytic degradation properties than those of cube-like counterparts and even commercial P25. Furthermore, ZrO₂ CNCs are easily recycled and can be used for the degradation of a range of dye systems.

Synthesis of transparent dispersions of aluminium hydroxide nanoparticles

Transparent dispersions of inorganic nanoparticles are attractive materials in many fields. However, a facile method for preparing such dispersions of aluminium hydroxide nanoparticles is yet to be realized. Here, we report a direct reactive method to prepare transparent dispersions of pseudo-boehmite nanoparticles (1 wt%) without any surface modification, and with an average particle size of 80 nm in length and 10 nm in width, as well as excellent optical transparency over 94% in the visible range. Furthermore, transparent dispersions of boehmite nanoparticles (1.5 wt%) were also achieved after an additional hydrothermal treatment. However, the optical transparency of dispersions decreased with the rise of hydrothermal temperature and the shape of particles changed from rhombs to hexagons. In particular, monodisperse hexagonal boehmite nanoplates with an average lateral size of 58 nm and a thickness of 12.5 nm were obtained at a hydrothermal temperature of 220 °C. The selectivity of crystal growth direction was speculated as the possible formation mechanism of these as-prepared aluminium hydroxide nanoparticles. Besides, two values of 19.6 wt% and 14.64 wt% were separately measured for the weight loss of pseudo-boehmite and boehmite nanoparticles after a continuous heating, indicating their potential flame-resistant applications in the fabrication of plastic electronics and optical devices with high transparency.