Determination of sulfur compounds in the sol–gel processing of GeS 2 by potentiometric titration

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The potentiometric titration method was used for quantitative determination of germanium sulfide and germanium mercaptide evolved during the sol–gel processing of GeS 2 from germanium ethoxide and H 2S. The titrations were performed in 2-propanol or in a 50–50 vol.% mixture of 2-propanol and toluene. The ion selective Ag/Ag 2S electrode was used for equivalence point detection. Study of the Nernst equation shows that complexes were formed at the electrode surface. However, the titration equivalence point volume clearly demonstrates the formation of Ag 2S and Ge(SAg) n . In order to explain this discrepancy, a new electrode reaction mechanism is suggested and a modified Ag/Ag 2S electrode potential equation is proposed.