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Aberration Corrected STEM Study of the Surface of Lead Chalcogenide Nanoparticles

2014; American Chemical Society; Volume: 118; Issue: 38 Linguagem: Inglês

10.1021/jp5057804

1932-7455

Domingo I. García-Gutiérrez, Diana F. García-Gutiérrez, Lina M. De León-Covián, Mario Tadeo Treviño-Gonzalez, Marco A. Garza-Navarro, Iván E. Moreno‐Cortez, R.F. Cienfuegos-Pelaes,

Gold and Silver Nanoparticles Synthesis and Applications

In this contribution, we report on the microscopic and spectroscopic characterization of lead chalcogenide nanoparticles. PbSe and PbTe nanoparticles were synthesized by chemical methods, using different molar ratios of Pb, Se, and Te precursors and varying the reaction time. These nanoparticles were characterized by means of transmission electron microscopy and their related techniques: electron diffraction, energy dispersive X-ray spectroscopy (EDXS), electron energy loss spectroscopy (EELS), and aberration corrected scanning transmission electron microscopy (AC-STEM), to obtain information related to their morphology, crystal structure, and composition. They were also characterized by means of Fourier transform infrared (FTIR) absorption spectroscopy to assess the functional groups found on the surface of the nanoparticles, depending on the synthesis conditions. The results obtained showed that the synthesized nanoparticles always display a higher concentration of Pb compared to that of the chalcogen. Moreover, the final concentration of Pb depended on the original ratio between the Pb precursor and the chalcogen precursor used in the synthesis. These variations in the composition influenced the FTIR absorption characteristics of the nanoparticles. EDXS, EELS, and AC-STEM results indicate that this excess of Pb is located on the surface of the nanoparticles, particularly in the amorphous capping layer. These results as well as those obtained from FTIR spectroscopy suggest that the protective layer is mostly made of lead oleate.