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Thermal evolution of ZnS nanostructures: effect of oxidation phenomena on structural features and photocatalytical performances

Thermal evolution of ZnS nanostructures: effect of oxidation phenomena on structural features and photocatalytical performances
Thermal evolution of ZnS nanostructures: effect of oxidation phenomena on structural features and photocatalytical performances

ZnS nanosystems are being extensively studied for their possible use in a wide range of technological applications. Recently, the gradual oxidation of ZnS to ZnO was exploited to tune their structural, electronic, and functional properties. However, the inherent complexity and size dependence of the ZnS oxidation phenomena resulted in a very fragmented description of the process. In this work, different-sized nanosystems were obtained through two different low temperature wet chemistry routes, namely, hydrothermal and inverse miniemulsion approaches. These protocols were used to obtain ZnS samples consisting of 21 and 7 nm crystallites, respectively, to be used as reference material. The obtained samples were then calcinated at different temperatures, ranging from 400 to 800 °C toward the complete oxidation of ZnO, passing through the coexistence of the two phases (ZnS/ZnO). A thorough comparison of the effects of thermal handling on ZnS structural, chemical, and functional evolution was carried out by TEM, XRD, XAS, XPS, Raman, FT-IR, and UV-Vis. Finally, the photocatalytic activity in the H2 evolution reaction was also compared for selected ZnS and ZnS/ZnO samples. A correlation between size and the oxidation process was observed, as the smaller nanosystems showed the formation of ZnO at lower temperature, or in a larger amount in the case of the ZnS and ZnO co-presence. A difference in the underlying mechanism of the reaction was also evidenced. Despite the ZnS/ZnO mixed samples being characterized by an increased light absorption in the visible range, their photocatalytic activity was found to be much lower.

0020-1669
13104-13114
Dengo, Nicola
200da580-00f6-47a9-8447-df81d5038488
De Fazio, Angela F.
e4115c3b-5447-4f30-8608-9e4115bc7d59
Weiss, Morten
46e2ef11-4046-43c3-9f0e-4355207e90e0
Marschall, Roland
10f1816e-6a01-4222-aeda-892ca55caa46
Dolcet, Paolo
44338168-eecc-4a57-852e-6bb3c21227e1
Fanetti, Mattia
a211cbfd-46df-47b9-bbed-83c8fed4a4ce
Gross, Silvia
2015f08a-b802-4f48-86f6-9f4fae250fb0
Dengo, Nicola
200da580-00f6-47a9-8447-df81d5038488
De Fazio, Angela F.
e4115c3b-5447-4f30-8608-9e4115bc7d59
Weiss, Morten
46e2ef11-4046-43c3-9f0e-4355207e90e0
Marschall, Roland
10f1816e-6a01-4222-aeda-892ca55caa46
Dolcet, Paolo
44338168-eecc-4a57-852e-6bb3c21227e1
Fanetti, Mattia
a211cbfd-46df-47b9-bbed-83c8fed4a4ce
Gross, Silvia
2015f08a-b802-4f48-86f6-9f4fae250fb0

Dengo, Nicola, De Fazio, Angela F., Weiss, Morten, Marschall, Roland, Dolcet, Paolo, Fanetti, Mattia and Gross, Silvia (2018) Thermal evolution of ZnS nanostructures: effect of oxidation phenomena on structural features and photocatalytical performances. Inorganic Chemistry, 57 (21), 13104-13114. (doi:10.1021/acs.inorgchem.8b01101).

Record type: Article

Abstract

ZnS nanosystems are being extensively studied for their possible use in a wide range of technological applications. Recently, the gradual oxidation of ZnS to ZnO was exploited to tune their structural, electronic, and functional properties. However, the inherent complexity and size dependence of the ZnS oxidation phenomena resulted in a very fragmented description of the process. In this work, different-sized nanosystems were obtained through two different low temperature wet chemistry routes, namely, hydrothermal and inverse miniemulsion approaches. These protocols were used to obtain ZnS samples consisting of 21 and 7 nm crystallites, respectively, to be used as reference material. The obtained samples were then calcinated at different temperatures, ranging from 400 to 800 °C toward the complete oxidation of ZnO, passing through the coexistence of the two phases (ZnS/ZnO). A thorough comparison of the effects of thermal handling on ZnS structural, chemical, and functional evolution was carried out by TEM, XRD, XAS, XPS, Raman, FT-IR, and UV-Vis. Finally, the photocatalytic activity in the H2 evolution reaction was also compared for selected ZnS and ZnS/ZnO samples. A correlation between size and the oxidation process was observed, as the smaller nanosystems showed the formation of ZnO at lower temperature, or in a larger amount in the case of the ZnS and ZnO co-presence. A difference in the underlying mechanism of the reaction was also evidenced. Despite the ZnS/ZnO mixed samples being characterized by an increased light absorption in the visible range, their photocatalytic activity was found to be much lower.

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e-pub ahead of print date: 10 October 2018

Identifiers

Local EPrints ID: 427375
URI: http://eprints.soton.ac.uk/id/eprint/427375
ISSN: 0020-1669
PURE UUID: 61e4c341-f329-489d-8be3-3335289745ea

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Date deposited: 14 Jan 2019 17:30
Last modified: 14 Jan 2019 17:30

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