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Interaction of diethyldithiocarbamate with n-type cadmium sulfide and cadmium selenide: efficient photoelectrochemical oxidation to the disulfide and flat-band potential of the semiconductor as a function of adsorbate concentration

Journal Article · · J. Am. Chem. Soc.; (United States)
DOI:https://doi.org/10.1021/ja00273a004· OSTI ID:5532489

The behavior of sodium diethyldithiocarbamate, Na(Et/sub 2/NCS/sub 2/), at n-type semiconducting CdX (X = S, Se) in CH/sub 3/CN/0.2 M NaClO/sub 4/ has been studied. The Et/sub 2/NCS/sub 2//sup -/ interacts strongly with the CdX surface and shifts the flat-band potential, E/sub FB/, up to 1.0 V more negative with increasing Et/sub 2/NCS/sub 2//sup -/ concentration. The concentration dependence of the shift in E/sub FB/ has been studied in the range 0-0.2 M, with 0.01 M Et/sub 2/NCS/sub 2//sup -/ being sufficient to shift E/sub FB/ the maximum amount. High current efficiency (at least 98%) can be maintained to large extent conversion (70%) in the photoelectrochemical oxidation of Et/sub 2/NCS/sub 2//sup -/ to (Et/sub 2/NC(S)S)/sub 2/ at either illuminated CdS or CdSe. Oxidation of Et/sub 2/NCS/sub 2//sup -/ can be effected at an electrode potential significantly more negative than E/sup 0/' of Et/sub 2/NCS/sub 2//sup -//(Et/sub 2/NC(S)S)/sub 2/, showing that visible light can be used to drive the oxidation in an uphill sense. Compared to a Pt anode, the CdX (X = S, Se) photoanodes allow a voltage savings of the order of 1.0 V. The photoanodes are durable and show constant output of at least 10 mA/cm/sup 2/ for greater than 48 h.

Research Organization:
Massachusetts Institute of Technology, Cambridge
OSTI ID:
5532489
Journal Information:
J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:13; ISSN JACSA
Country of Publication:
United States
Language:
English