Photocatalytic performance of CdS nanomaterials for photodegradation of organic azo dyes under artificial visible light and natural solar light irradiation

The CdS semiconductors have been prepared at low temperature via catalyst-free chemical precipitation method without using any surfactant or capping agent. Either water or ethylene glycol, as a solvent, provides spherical CdS nanostructures with a comparable size of 117–121 nm. The molar ratio of Cd/S plays an important role in determining phase structure, morphology and photocatalytic performance of the prepared CdS nanostructures. Increasing molar ratio of S^2? results in not only mixed cubic-hexagonal phases but also low photocatalytic performance. CdS nanoparticles with good dispersibility prepared at Cd/S molar ratio of 1:1 shows high photocatytic efficiency of 95% toward photodegradation of reactive red azo dye (RR141) under visible light irradiation up to 240 min. The degradation efficiency of CdS nanoparticles also reaches 48% under natural solar light irradiation for 80 min. This work demonstrates the promising potential of CdS nanomaterials as photocatalysts for environmental remediation.     

The Influence of Solvent Properties and Functionality on the Electrospinnability of Polystyrene Nanofibers

Summary: In order to produce nanometer‐sized fibers at an industrial scale, not only the morphology but also the production rate of fibers is important. The effect of solvent properties and functionality on the production rate of electrospun PS nanofibers was investigated using eighteen different solvents. The solution concentration was varied between 10 and 30% w/v. Electrospinning of PS solutions was carried out at various applied voltages and tip‐to‐collector distances The production rate of the obtained PS nanofibers was quantified in terms of electrospinnability. We found that the chance for the resulting PS solution to be spinnable is greater for solvents with high dipole moment and low viscosity. The solvent that provided the highest electrospinnability for polystyrene was DMF and the functionalities that promoted high dipole moment and thus high spinnability were the carbonyl group and the nitrogen group with free electrons. General guidelines for choosing suitable solvents for successful production of electrospun nanofibers have also been proposed.

SEM image of PS 685D at 200× magnification and the %‐coverage of the fibers obtained by using DMF, chloroform, and 1,4‐dioxane.