Suchergebnisse

Wurtzite based materials have the advantages of being cheap, no-toxic and offering excellent opto-electrical, piezoelectric and pyroelectric properties. The nanocrystalline wurtzite ZnS, being a room temperature stable material unlike its bulk counterpart, is interesting because of its potential in piezoelectric and pyroelectric energy harvesting. In this work we aimed to tailor a simple synthesis method for nanocrystalline wurtzite production, which would be easy to scale up. We used the well-known reaction of zinc chloride with thiourea or sodium sulfide dissolved in ethyl glycol at a carefully controlled molar ratio in medium temperature conditions (140-150°C) to produce pure, nanocrystalline ZnS in the hexagonal (wurtzite) phase, via a series of consecutive experiments. The amount of solvent was kept the same (60 ml of ethyl glycol) by re-using what remained of the solvent from the previous reaction and topping up the quantity lost. The productivity yield increased over 6 successive reactions from 156 mg to 446 mg per batch at a constant mMZn/mMS = 1 ratio. The obtained nanopowder has been characterized using TG, BET, FTIR, TEM and SEM techniques. Our plan is to build an in-house pilot plant that should produce substantial amounts of wurtzite ZnS nano-powder in an environmentally friendly and cost effective way. Acknowledgement: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 797951.

Pyroelectric materials can harvest energy from naturally occurring ambient temperature change, as well as from artificial temperature change, notably from industrial activity. At a time of climate emergency, pyroelectric energy harvesting is a highly promising technology that should ultimately lead to the development of autonomous and self-powered electronic devices and which has the potential to harvest enormous amount of wasted heat. One interesting but rarely studied class of pyroelectric materials are non-ferroelectric pyroelectrics; these include semiconductor materials with a wurtzite crystalline structure such as CdS, ZnO or ZnS. We studied ZnS, and explored a simple, co-precipitation synthesis for nanocrystalline wurtzite ZnS production. The structural, morphological and dielectric properties of two selected samples were investigated to examine the effects of different molar concentrations of precursor Zn and S ions (mMZn/mMS = 0.47 and 1.22) in the reactive solution. Alongside these results, we present our recently built in-house semi-pilot plant that is able to produce substantial amounts of wurtzite ZnS nanopowder in an environmentally friendly and cost effective way. The obtained ZnS nanopowder is intended both as a precursor for pyroelectric ceramics and as a filler for ferroelectric polymer-based composite thin films (PVDF co-polymers). Acknowledgement: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 797951. This project was also partially supported by the Piano triennale di realizzazione 2019-2021 della ricerca di sistema elettrico nazionale – Progetto 1.3 Materiali di frontiera per usi energetici (C.U.P. code: I34I19005780001). ; This project was also partially supported by the Piano triennale di realizzazione 2019-2021 della ricerca di sistema elettrico nazionale – Progetto 1.3 Materiali di frontiera per usi energetici (C.U.P. code: I34I19005780001).

AbstractAnthropogenic plastic litter is widespread in all environments, with particular emphasis on aquatic habitats. Specifically, although freshwater mammals are important as they are at the top of food web, research mainly focus on marine animals, while only few studies have been carried out on freshwater mammals. The main gap is that microplastics (MP) are completely understudied in freshwater mammals. Here, we reported the first evidence of the presence of anthropogenic particles (including MP) in coypu (Myocastor coypus)' faeces. Coypu is a rodent mammal inhabiting rivers and wetland areas, and we discussed our preliminary data suggesting the use of these tracks as possible future bioindicator of MP pollution in wetlands and freshwaters. We collected 30 coypu's faeces in "Torre Flavia wetland" nature reserve. Then, in laboratory, faeces were digested in 30 ml hydrogen peroxide (30%) for a week a 20 °C and analysed under stereoscope. All the suspected found MP were isolated in a petri dish, using FT-IR analysis to confirm the polymers. Overall, we recorded 444 natural and anthropogenic particles with most of items being fibres. FT-IR analysis of the 10% of the particles recovered revealed that 72% of them was not MP (mainly, polyethylene, polyethylene terephthalate, and polyamide). Also, the number of anthropogenic particles is not correlated with the faecal weight. Given that alien species, such as coypu, are widespread species, our results might have a great importance as these species and MP in faecal tracks may be used as undirect proxy of environmental bioavailability of MP pollution.