Cant, David, Syres, Karen, Lunt, Patrick, Radtke, Hanna, Treacy, Jon, Thomas, P. John, Lewis, Edward A., Haigh, Sarah J., O’Brien, Paul, Schulte, Karina, Bondino, Federica, Magnano, Elena and Flavell, Wendy R. (2015) Surface Properties of Nanocrystalline PbS Films Deposited at the Water–Oil Interface: A Study of Atmospheric Aging. Langmuir, 31 (4). pp. 1445-1453. ISSN 0743-7463
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Official URL: http://dx.doi.org/10.1021/la504779h
Nanocrystalline thin films of PbS are obtained in a straightforward reaction by precipitation at the interface between toluene (containing a Pb precursor) and water (containing Na2S). Lead thiobiuret [Pb(SON(CN(i)Pr2)2)2] and lead diethyldithiocarbamate [Pb(S2CNEt2)2] precursors are used. The films are characterized by X-ray diffraction and electron microscopy, revealing typical particle sizes of 10-40 nm and preferred (200) orientation. Synchrotron-excited depth-profiling X-ray photoelectron spectroscopy (XPS) is used to determine the depth-dependent chemical composition as a function of surface aging in air for periods of up to 9 months. The as-synthesized films show a 1:1 Pb/S composition. Initial degradation occurs to form lead hydroxide and small quantities of surface-adsorbed -SH species. A lead-deficient Pb1-xS phase is produced as the aging proceeds. Oxidation of the sulfur occurs later to form sulfite and sulfate products that are highly localized at the surface layers of the nanocrystals. These species show logarithmic growth kinetics, demonstrating that the sulfite/sulfate layer acts to passivate the nanocrystals. Our results demonstrate that the initial reaction of the PbS nanocrystals (forming lead hydroxide) is incongruent. The results are discussed in the context of the use of PbS nanocrystals as light-harvesting elements in next-generation solar technology.
|Subjects:||Physical sciences > Physics|
Physical sciences > Chemistry
|Schools:||Faculty of Science and Technology > School of Physical Sciences and Computing|
|Deposited By:||Karen Syres|
|Deposited On:||20 Apr 2015 11:47|
|Last Modified:||09 Aug 2016 15:21|
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