Dynamic Light Scattering and X‑ray Photoelectron Spectroscopy Characterization of PEGylated Polymer Nanocarriers: Internal Structure and Surface Properties

In this work, nanospheres and nanocapsules are precipitated in confined impinging jet mixers through solvent displacement and characterized. Acetone and water are used as the solvent and antisolvent, respectively, together with polymethoxypolyethylene glycol cyanoacrylate-<i>co</i>-hexadecylcyanoacrylate and Miglyol as the copolymer and oil, respectively. Characterization is performed with dynamic light scattering, with electrophoretic measurements, and for the first time with X-ray photoelectron spectroscopy. Results show that the presence of polyethylene glycol chains seems to be more pronounced on the surface of nanospheres than on that of nanocapsules. The thickness of the copolymer layer in nanocapsules ranges from 1 to 10 nm, depending on the value of the oil:copolymer mass ratio. Fast dilution is confirmed to have a positive effect in suppressing aggregation but can induce further copolymer precipitation

Optimization of 1D ZnO@TiO₂ Core–Shell Nanostructures for Enhanced Photoelectrochemical Water Splitting under Solar Light Illumination

A fast and low-cost sol–gel synthesis used to deposit a shell of TiO₂ anatase onto an array of vertically aligned ZnO nanowires (NWs) is reported in this paper. The influence of the annealing atmosphere (air or N₂) and of the NWs preannealing process, before TiO₂ deposition, on both the physicochemical characteristics and photoelectrochemical (PEC) performance of the resulting heterostructure, was studied. The efficient application of the ZnO@TiO₂ core–shells for the PEC water-splitting reaction, under simulated solar light illumination (AM 1.5G) solar light illumination in basic media, is here reported for the first time. This application has had a dual function: to enhance the photoactivity of pristine ZnO NWs and to increase the photodegradation stability, because of the protective role of the TiO₂ shell. It was found that an air treatment induces a better charge separation and a lower carrier recombination, which in turn are responsible for an improvement in the PEC performance with respect to N₂-treated core–shell materials. Finally, a photocurrent of 0.40 mA/cm² at 1.23 V versus RHE (2.2 times with respect to the pristine ZnO NWs) was obtained. This achievement can be regarded as a valuable result, considering similar nanostructured electrodes reported in the literature for this application