Volume 66, 1970

Surface chemistry of sulphides. Part 1.—Infra-red study of molybdenum and germanium sulphides and of their reaction with H2, H2O, thiophene and ethanethiol

Abstract

SH stretching vibrations on the surfaces of reduced GeSx(x≃ 1.4) and MoS2 have been observed in the infra-red domain of 2500–2700 cm–1. In GeSx, a single broad band at 2575 cm–1 shifts towards higher frequencies on heating to 200°C. In MoS2 two bands are observed at 2640 and 2500 cm–1; they decrease in intensity at increasing temperature. Chemisorption of an electron donor, such as H2O, on reduced GeSx produces a doubling of the SH band, with a high-frequency component above 2700 cm–1 and a low-frequency component around 2500 cm–1. The same observation has been made by adsorbing thiophene below 200°C. The study of the CH stretching region permits the assignment of the infra-red features in this temperature range to 2-point (or 4-point) attachment of thiophene, and eventually, to butene attached by the double bond. Above 200°C, in GeSx and from 20–400°C on MoS2, the infra-red spectra show the transformation of chemisorbed thiophene into 1- or 2-butene and into acetylenic and vinyledenic radicals. The same radicals are observed on adsorbing ethanethiol on GeSx. At low temperature, however, ethyl surface groups are probably more abundant. Conductivity measurements performed during the chemisorption of thiophene on GeSx support the conclusion that the adsorbate transfers electrons to the solid at low temperature.

Article information

Article type
Paper

Trans. Faraday Soc., 1970,66, 2897-2910

Surface chemistry of sulphides. Part 1.—Infra-red study of molybdenum and germanium sulphides and of their reaction with H2, H2O, thiophene and ethanethiol

P. Ratnasamy and J. J. Fripiat, Trans. Faraday Soc., 1970, 66, 2897 DOI: 10.1039/TF9706602897

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