Non-injection synthesis of monodisperse Cu-Fe-S nanocrystals and their size dependent properties
PBN-AR
Instytucja
Wydział Chemiczny (Politechnika Warszawska)
Informacje podstawowe
Główny język publikacji
en
Czasopismo
Physical Chemistry Chemical Physics
ISSN
1463-9076
EISSN
Wydawca
RSC Publications
DOI
Rok publikacji
2016
Numer zeszytu
22
Strony od-do
15091-15101
Numer tomu
18
Identyfikator DOI
Liczba arkuszy
0.5
Streszczenia
Język
en
Treść
It 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.
Inne
System-identifier
WUT57d82ed6fc844c1e926edcdb2d769d5d
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