Direct Preparation of Sulfide Semiconductor Nanoparticles from the Corresponding Bulk Powders in an Ionic Liquid

Photocatalytic degradation of methyl orange, methylene blue and rhodamine B with AgCl nanocatalyst synthesised from its bulk material in the ionic liquid [P6 6 6 14]Cl

The photocatalytic degradation of wastewater containing three industrial dyes belonging to different families, methyl orange (MO), methylene blue (MB) and Rhodamine B (RhB), was studied under UV-Vis irradiation using synthesised silver chloride nanoparticles. The nanocatalyst was prepared by a dissolution/reprecipitation method starting from the bulk powder and the ionic liquid trihexyl(tetradecyl)phosphonium chloride, [P_{6 6 6 14}]Cl, without addition of other solvents. The obtained catalyst was characterised by UV-Vis absorbance, X-ray powder diffraction, transmission electron microscopy and scanning electron microscopy. The decolourisation of the samples was studied by UV-Vis absorbance at the corresponding wavelength. Starting from 10 ppm dye solutions and 1 g L^-1 of the synthesised AgCl nanoparticles, degradation efficiencies of 98.4% for MO, 98.6% for MB and 99.9% for RhB, were achieved in 1 h. The degradation mechanisms for the different dyes were studied. Comparison with other frequently used nanocatalysts, namely P-25 Degussa, TiO₂ anatase, Ag and ZnO, highlights the strong catalytic activity of AgCl nanoparticles. Under the same experimental conditions, these nanoparticles led to higher (more than 10%) and faster degradations.

Geometric matching principle for adsorption selectivity of ionic liquids: a simple method into the fascinating world of shape-controlled chemistry

Ionic liquids (ILs) possess effective functions in controlling the phase and morphology of nanomaterials. However, it is still unclear how ILs affect the morphology control and what the origin of adsorption selectivity of ILs is on different crystal facets. It is a challenge to develop a simple method to select the suitable kinds of ILs for achieving the controllable synthesis of nanomaterials with designable shape. Herein, density functional theory (DFT) calculations were combined with experiment to study the interaction mechanism between ILs and crystal facets. An important relationship is proposed, named as the geometric matching principle, in which the adsorption site of substrate should not only need to meet the space requirement for interionic stacking of ILs, but also needs to maximize the interaction between adsorbed ILs and substrate. This new finding is meaningful for prediction of the adsorption selectivity of ILs and clarification of their shape-controlled chemistry.