Non-injection synthesis of monodisperse Cu-Fe-S nanocrystals and their size dependent properties
Grzegorz Gąbka , Piotr Bujak , Jan Żukrowski , Damian Zabost , Kamil Kotwica , Karolina Malinowska , Andrzej Ostrowski , Ireneusz Wielgus , Wojciech Lisowski , Janusz W. Sobczak , Marek Przybylski , Adam Proń
AbstractIt is demonstrated that ternary Cu-Fe-S nanocrystals differing in composition (from Cu-rich to Fe-rich), structure (chalcopyrite or high bornite) and size can be obtained from a mixture of CuCl, FeCl3, thiourea and oleic acid (OA) in oleylamine (OLA) using the heating up procedure. This new preparation method yields the smallest Cu-Fe-S nanocrystals ever reported to date (1.5 nm for high bornite structure and 2.7 nm for chalcopyrite one). A comparative study of nanocrystals of the same composition (Cu1.6Fe1.0S2.0) but different in size (2.7 nm and 9.3 nm) revealed a pronounced quantum confinement effect, confirmed by three different techniques: UV-vis spectroscopy, cyclic voltammetry and Mössbauer spectroscopy. The optical band gap increased from 0.60 eV in the bulk material to 0.69 eV in nanocrystals of 9.3 nm size and to 1.39 eV in nanocrystals of 2.7 nm. The same trend was observed in electrochemical band gaps, derived from cyclic voltammetry studies (band gaps of 0.74 eV and 1.54 eV). The quantum effect was also manifested in Mössbauer spectroscopy by an abrupt change of the spectrum from quadrupole doublet to a Zeeman sextet below 10 K, which could be interpreted in terms well defined energy states in these nanoparticles, resulting from the quantum confinement. Mössbauer spectroscopic data confirmed in addition the results of XPS spectroscopy implying the co-existence of Fe(III) and Fe(II) in the synthesized nanocrystals. Organic shell composition was investigated by NMR spectroscopy (after dissolution of the inorganic core) and by IR. Both methods identified oleylamine (OLA) and 1-octadecene (ODE) as surfacial ligands, the latter being formed in situ via an elimination-hydrogenation reaction occurring between OLA and the nanocrystal surface.
|Journal series||Physical Chemistry Chemical Physics, ISSN 1463-9076|
|Publication size in sheets||0.5|
|Score|| = 40.0, 28-11-2017, ArticleFromJournal|
= 40.0, 28-11-2017, ArticleFromJournal
|Publication indicators||: 2016 = 4.123 (2) - 2016=4.242 (5)|
|Citation count*||9 (2018-02-19)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.