Synthesis and characterization of lead sulphide nanoparticles from lead alkyl xanthate single source precursors using a solventless method

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Xanthates have been successfully investigated as single source precursors for producing metal sulphide nanoparticles. These offer advantages over other precursors because they have low decomposition pathways, they are cheap, they are clean and they have pre-formed M-S bond. Although ethyl xanthates have been investigated with much success, there are few or no reports on the syntheses of higher alkyl xanthates. In this work a series of lead alkyl xanthates have been synthesized with the alkyl groups being ethyl, n-butyl, 1- hexyl and 1-octyl. The purities of the precursors were confirmed by micro-elemental analyses. Infra-red, 1H NMR, 13C NMR, melting point, and mass spectroscopy were also used to characterize the precursors. The thermal behaviours of the precursors were determined by TGA and DSC. The crystal structure of lead hexyl xanthate was determined. The low melting points recorded for the precursors confirmed that the lead alkyl xanthates could be used as single source precursors in low thermal decomposition for the syntheses of lead sulphide nanoparticles. The PbS nanoparticles were then produced using the melt method which is a rapid, less toxic and cheap process. The as-prepared lead sulphide nanoparticles were characterized by XRD and TEM which confirmed a growth towards cubic PbS phases. The calculated particle sizes from the Debye Scherer equation were 26.45, 25.17, 24.79 and 23.32 nm for the PbS nanoparticles obtained from the decomposition of ethyl, butyl, hexyl and lead octyl xanthate respectively. SEM and EDX were also used to determine the morphology and purity of the as-prepared PbS nanoparticles respectively.
A Thesis submitted to the Department of Chemistry, College of Science, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the degree of MPhil in Polymer Science and Technology