With the large amount of attention being given to microplastics in the environment, several researchers have begun to consider the fragmentation of plastics down to lower scales (i.e., the sub-micrometer scale). The term "nanoplastics" is still under debate, and different studies have set the upper size limit at either 1000 nm or 100 nm. The aim of the present work is to propose a definition of nanoplastics, based on our recently published and unpublished research definition of nanoplastics. We define nanoplastics as particles unintentionally produced (i.e. from the degradation and the manufacturing of the plastic objects) and presenting a colloidal behavior, within the size range from 1 to 1000 nm.

This work deals with nickel electronucleation and growth processes onto a glassy carbon electrode from NiCl2·6H2O dissolved in ethylene glycol (EG) solutions with and without 250 mM NaCl as a supporting electrolyte. The physicochemical properties of EG solutions, namely, viscosity and conductivity, were determined for different Ni­(II) concentrations. From cyclic voltammetry, it was found that in the absence of the supporting electrolyte, the cathodic efficiency of Ni electrodeposition is about 88%; however, in the presence of the supporting electrolyte, the cathodic efficiency was reduced to 26% due to water (added along the supporting electrolyte) reduction on the growing surfaces of Ni nuclei. This side reaction produced both H2(g) and OH– ions. Part of the former was occluded in Ni, and the latter reacted with Ni­(II) ions in EG forming passivation products such as Ni­(OH)2(s). Moreover, it was shown that metallic Ni did not catalyze the EG reduction in this system. From chronoamperometry, it was shown that in the absence of the supporting electrolyte, the amount of Ni electrodeposits, for the same overpotential and time, was higher than in the presence of the supporting electrolyte. The j–t plots recorded in the latter system, for different Ni­(II) concentrations, were analyzed using a model which involves a contribution due to multiple 3D nucleation and diffusion-controlled growth and another related to the simultaneous reduction of water on the Ni nuclei growing surfaces. This model allows not only the quantification of the Ni nucleation kinetic parameters but also the effective deconvolution of the individual contributions to the total current; thus, from the integration of the j–t plots of these contributions, it was demonstrated that the charge amount of each process depends on the Ni­(II) concentration. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy revealed the presence of pure Ni nanoparticles electrodeposited on the electrode surface. Moreover, X-ray measurements verified the formation of a high-crystallinity face-centered cubic structure with preferred orientation growth on the ⟨111⟩ direction, which were also corroborated by the magnetic measurement performed in a physical property measurement system.

This work presents a thorough study on the early stage of copper electrodeposition from a choline chloride-urea deep eutectic solvent (DES). Determination of possible species in DES containing Cu2+ ions as the electrolytes has been performed using UV-Vis measurements. Kinetic and thermodynamic aspects of copper electrodeposition on glassy carbon electrode from DES were thoroughly investigated using cyclic voltammetry (CV) and chronoamperometry (CA). Both results from CA and CV have demonstrated that the copper electrodeposition could be performed directly from DES containing a small amount of water by the single potentiostatic step technique. Theoretical approach confirmed that the direct electronucleation of copper nanoparticles in the DES can be described by a model with two contributions, namely, (i) adsorption process and (ii) a three-dimensional (3D) nucleation and diffusion-controlled growth of copper nuclei, to the total current density transients. Kinetic parameters are important for controlling morphology and chemical composition of the obtained nanoparticles, which are verified by surface characterization techniques such as SEM and EDS.