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

Abstract

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.

ZrO2-Based Photocatalysts for Wastewater Treatment: From Novel Modification Strategies to Mechanistic Insights

“…Thus, the parameters like shape and size intensities were influenced by the presence of defects that leads to the lowering of electron-hole pairs reassembly which contributed to boosted photocatalytic activity. In a different study, the cube-like or star-like morphology of the ZrO 2 colloidal nanocrystal clusters (CNCs) was also observed by varying the reaction conditions [47]. The occurrence of Cl − ions in the hydrothermal process resulted in the establishment of cube-like ZrO 2 CNCs with a rough surface and increased particle size from 74 to 170 nm by incrementing the reaction time (six to ten hours).…”